Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.054
Pavlo A. Sytnykov
The structure and properties of plasma coatings sprayed with a composite material based on a self-fluxing NiCrBSi alloy (PG-10N-01 alloy) modified with a composite material obtained by self-propagating high-temperature synthesis were studied. Titanium powders, carbon black, aluminum, iron oxide, PT-NA-01 thermosetting powder and PGOSA-0 refractory clay were used as the initial components of modified with a composite material. Mixing and mechanical activation of the initial powders was carried out in a BM-1 ball mill for 15 minutes at 130 rpm in a ratio of 1 to 40 of the mass of the charge to the mass of the falling bodies (steel balls with a diameter of 6 mm). Initiation of the self-propagating high-temperature synthesis was carried out using a special device by introducing a heated nichrome spiral. The process of coatings spraying was performed on the MPN-004 microplasma spraying unit at a current of 45 A, a voltage of 30 V with a distance of 100 mm on samples made of 65G steel with a thickness of 3 mm. Argon was used as a plasma-forming and shielding gas. In order to substantiate the feasibility of the self-propagating high-temperature synthesis, a part of the samples was sprayed with a self-fluxing alloy PG-10N-01 with the addition of a mechanical mixture of starting powders. It was established that as a result of plasma spraying of the PG-10N-01 alloy and the composite material of the modified with a composite material + PG-10N-01 composition, coatings with a dense and multiphase structure are formed. The microstructure of the PG-10N-01 alloy coating consists of a solid solution based on nickel (γ-Ni) with inclusions of nickel borides Ni3B and chromium carbides Cr3C2. When adding modified with a composite material in a nickel-based solid solution, in addition to the phases indicated above, borides of titanium TiB2, carbides of titanium TiC and silicon SiC were detected. Their presence leads to an increase in the microhardness of such coatings and their greater wear resistance under conditions of abrasive wear in comparison with the spraying coating of the PG-10H-01 alloy.
{"title":"Plasma Coatings Based on Self-Fluxing NiCrBSi Alloy with Improved Wear Resistance Properties","authors":"Pavlo A. Sytnykov","doi":"10.15407/pmach2023.03.054","DOIUrl":"https://doi.org/10.15407/pmach2023.03.054","url":null,"abstract":"The structure and properties of plasma coatings sprayed with a composite material based on a self-fluxing NiCrBSi alloy (PG-10N-01 alloy) modified with a composite material obtained by self-propagating high-temperature synthesis were studied. Titanium powders, carbon black, aluminum, iron oxide, PT-NA-01 thermosetting powder and PGOSA-0 refractory clay were used as the initial components of modified with a composite material. Mixing and mechanical activation of the initial powders was carried out in a BM-1 ball mill for 15 minutes at 130 rpm in a ratio of 1 to 40 of the mass of the charge to the mass of the falling bodies (steel balls with a diameter of 6 mm). Initiation of the self-propagating high-temperature synthesis was carried out using a special device by introducing a heated nichrome spiral. The process of coatings spraying was performed on the MPN-004 microplasma spraying unit at a current of 45 A, a voltage of 30 V with a distance of 100 mm on samples made of 65G steel with a thickness of 3 mm. Argon was used as a plasma-forming and shielding gas. In order to substantiate the feasibility of the self-propagating high-temperature synthesis, a part of the samples was sprayed with a self-fluxing alloy PG-10N-01 with the addition of a mechanical mixture of starting powders. It was established that as a result of plasma spraying of the PG-10N-01 alloy and the composite material of the modified with a composite material + PG-10N-01 composition, coatings with a dense and multiphase structure are formed. The microstructure of the PG-10N-01 alloy coating consists of a solid solution based on nickel (γ-Ni) with inclusions of nickel borides Ni3B and chromium carbides Cr3C2. When adding modified with a composite material in a nickel-based solid solution, in addition to the phases indicated above, borides of titanium TiB2, carbides of titanium TiC and silicon SiC were detected. Their presence leads to an increase in the microhardness of such coatings and their greater wear resistance under conditions of abrasive wear in comparison with the spraying coating of the PG-10H-01 alloy.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.028
Mykhailo M. Hrebennikov, Oleksandr H. Dibir, Anatolii O. Kyrpikin, Mykola I. Pekelnyi
This paper is dedicated to ensuring the strength of cargo equipment elements of transport aircraft. The strength of rollers of roller conveyors, which are made of standard pressed aluminum tubular profiles or composite tubular elements, is considered. The main disadvantage of these semi-finished products is the deviation of the diameter of these standard aluminum profiles, which leads to the emergence of eccentricity Δ between the axes of the outer and inner surfaces. The influence of eccentricity on the change in the values of normal and tangential stresses is considered. This analysis was carried out for standard diameters of tubular profiles at values Δ equal to half of the standard limit deviation of the outer diameter D. Calculations of normal and tangential stresses and their comparison with nominal stresses that occur in the absence of misalignment have been carried out. Calculations were made of the value c of the removal of the center of rigidity from the center of the circle of the outer border of the cross-section at different cross-section sizes of standard profiles with values of Δ equal to half of the standard limit deviation of the outer diameter D inclusively. The calculations showed an increase in tangential stresses τ in some cases by 64% and even by 213%. The obtained results indicate that the presence of Δ≠0 will have a negative effect on the resource of these elements. In order to eliminate the negative consequences, it is necessary to increase the requirements for the shape deviation of the tubular profiles in the input control.
{"title":"Calculation of the Tubular Elements Made of Pressed Profiles","authors":"Mykhailo M. Hrebennikov, Oleksandr H. Dibir, Anatolii O. Kyrpikin, Mykola I. Pekelnyi","doi":"10.15407/pmach2023.03.028","DOIUrl":"https://doi.org/10.15407/pmach2023.03.028","url":null,"abstract":"This paper is dedicated to ensuring the strength of cargo equipment elements of transport aircraft. The strength of rollers of roller conveyors, which are made of standard pressed aluminum tubular profiles or composite tubular elements, is considered. The main disadvantage of these semi-finished products is the deviation of the diameter of these standard aluminum profiles, which leads to the emergence of eccentricity Δ between the axes of the outer and inner surfaces. The influence of eccentricity on the change in the values of normal and tangential stresses is considered. This analysis was carried out for standard diameters of tubular profiles at values Δ equal to half of the standard limit deviation of the outer diameter D. Calculations of normal and tangential stresses and their comparison with nominal stresses that occur in the absence of misalignment have been carried out. Calculations were made of the value c of the removal of the center of rigidity from the center of the circle of the outer border of the cross-section at different cross-section sizes of standard profiles with values of Δ equal to half of the standard limit deviation of the outer diameter D inclusively. The calculations showed an increase in tangential stresses τ in some cases by 64% and even by 213%. The obtained results indicate that the presence of Δ≠0 will have a negative effect on the resource of these elements. In order to eliminate the negative consequences, it is necessary to increase the requirements for the shape deviation of the tubular profiles in the input control.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.042
Borys I. Kuznetsov, Ihor V. Bovdui, Olena V. Voloshko, Tetyana B. Nikitina, Borys B. Kobylianskyi
A multicriteria parametric optimization of nonlinear robust control with two degrees of freedom by a discrete-continuous plant has been developed to increase accuracy and reduce sensitivity to uncertain plant parameters. Such plants are mounted on a moving base, on which sensors for angles, angular velocities and angular accelerations are installed. To increase the accuracy of control, systems with two degrees of freedom, which include control with feedback and a closed-loop, and with direct connections and open-loop control of the setting and disturbing effects, are used. The multicriteria optimization of nonlinear robust control with two degrees of freedom by a discrete-continuous plant is reduced to the solution of the Hamilton-Jacobi-Isaacs equations. The robust control target vector is calculated as a solution of a zero-sum antagonistic vector game. The vector payoffs of this game are direct indexes performance vector presented in the system in different modes of its operation. The calculation of the vector payoffs of this game is related to the simulation of the synthesized nonlinear system for different operating modes of the system, input signals and values of the plant parameters. The solutions of this vector game are calculated on the basis of the system of Pareto-optimal solutions, taking into account the binary relations of preferences, on the basis of the stochastic metaheuristic of Archimedes optimization algorithm by several swarms. Thanks to the synthesis of nonlinear robust control with two degrees of freedom by a discrete-continuous object, it is shown that the use of synthesized controllers made it possible to increase the accuracy of control of an electromechanical system with distributed parameters of the mechanical part to reduce the time of transient processes by 1.5–2 times, reduce dispersion of errors by 1.3 times and reduce the sensitivity of the system to changes in the plant parameters in comparison with typical controllers used in existing systems. Further improvement of control accuracy is restrained by energy limitations of executive mechanisms and information limitations of measuring devices.
{"title":"Multicriteria Parametric Optimization of Nonlinear Robust Control with Two Degrees of Freedom by a Discrete-Continuous Plant","authors":"Borys I. Kuznetsov, Ihor V. Bovdui, Olena V. Voloshko, Tetyana B. Nikitina, Borys B. Kobylianskyi","doi":"10.15407/pmach2023.03.042","DOIUrl":"https://doi.org/10.15407/pmach2023.03.042","url":null,"abstract":"A multicriteria parametric optimization of nonlinear robust control with two degrees of freedom by a discrete-continuous plant has been developed to increase accuracy and reduce sensitivity to uncertain plant parameters. Such plants are mounted on a moving base, on which sensors for angles, angular velocities and angular accelerations are installed. To increase the accuracy of control, systems with two degrees of freedom, which include control with feedback and a closed-loop, and with direct connections and open-loop control of the setting and disturbing effects, are used. The multicriteria optimization of nonlinear robust control with two degrees of freedom by a discrete-continuous plant is reduced to the solution of the Hamilton-Jacobi-Isaacs equations. The robust control target vector is calculated as a solution of a zero-sum antagonistic vector game. The vector payoffs of this game are direct indexes performance vector presented in the system in different modes of its operation. The calculation of the vector payoffs of this game is related to the simulation of the synthesized nonlinear system for different operating modes of the system, input signals and values of the plant parameters. The solutions of this vector game are calculated on the basis of the system of Pareto-optimal solutions, taking into account the binary relations of preferences, on the basis of the stochastic metaheuristic of Archimedes optimization algorithm by several swarms. Thanks to the synthesis of nonlinear robust control with two degrees of freedom by a discrete-continuous object, it is shown that the use of synthesized controllers made it possible to increase the accuracy of control of an electromechanical system with distributed parameters of the mechanical part to reduce the time of transient processes by 1.5–2 times, reduce dispersion of errors by 1.3 times and reduce the sensitivity of the system to changes in the plant parameters in comparison with typical controllers used in existing systems. Further improvement of control accuracy is restrained by energy limitations of executive mechanisms and information limitations of measuring devices.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.015
Olha Yu. Chernousenko, Vitalii A. Peshko, Oleksandr P. Usatyi
In practice, during the operation of steam turbines, accidental damage to the blades of the rotors and stators of powerful steam turbines occurs. The main causes of emergency stops of steam turbines were vibration fatigue of the blades material, erosive damage to the blades body, and resonance problems during the power equipment operation. Based on this study, the assessment of changes in the thermal and stress-strain state of power equipment elements, which at nuclear power plants significantly affect the continued operation of the turbine after its damage, are quite relevant. Changes in the thermal and stress-strain state, which may occur after damage to the rotor of high-pressure cylinder (HPC rotor) of the K-1000-60/3000 turbine power unit of the LMZ in the station conditions, have been considered and analyzed and will provide an opportunity to assess the individual resource and continue the power unit operation. In the calculated assessment of changes in the thermal and stress-strain state of the HPC rotor, taking into account the data of the technical audit regarding damage, a geometric model of the rotor was created. Studies were conducted for three options of designs: the original option (five stages of the HPC rotor), the option without the blades of the last stage and the option without the fifth stage (with four first stages). For the project design, when working at the nominal parameters of the steam, the most stressed areas are the unloading holes of the 5th stage (σi=202.8 MPa), axial hole of the rotor in the area of the 5th stage (σi=195.2 MPa), as well as the 5th-degree welding fillet from the side of the end seals (σi=200.3 MPa) and unloading holes of the 4th and 3rd stages with a stress intensity of about 170–185 MPa. The high values of the stress intensity in the area of the 5th stage can be explained by the significant concentration of the mass of both the stage itself and its blades, which provoke significant centrifugal forces when working at the nominal rotation frequency. For a HPC rotor without blades of the 5th stage, there is a shift of the maximum stress intensity to the area of the unloading holes of the 4th and 3rd stages, as well as the axial hole of the shaft under the same stages. The maximum stress value is σi max=184.8 MPa. At the same time, the intensity of stresses in the area of unloading holes of the 5th degree decreased almost by half, to the level of 124 MPa.
{"title":"Changes in the Thermal and Stress-Strain State of the HPC Rotor of a Powerful NPP Turbine after the Blades Damage","authors":"Olha Yu. Chernousenko, Vitalii A. Peshko, Oleksandr P. Usatyi","doi":"10.15407/pmach2023.03.015","DOIUrl":"https://doi.org/10.15407/pmach2023.03.015","url":null,"abstract":"In practice, during the operation of steam turbines, accidental damage to the blades of the rotors and stators of powerful steam turbines occurs. The main causes of emergency stops of steam turbines were vibration fatigue of the blades material, erosive damage to the blades body, and resonance problems during the power equipment operation. Based on this study, the assessment of changes in the thermal and stress-strain state of power equipment elements, which at nuclear power plants significantly affect the continued operation of the turbine after its damage, are quite relevant. Changes in the thermal and stress-strain state, which may occur after damage to the rotor of high-pressure cylinder (HPC rotor) of the K-1000-60/3000 turbine power unit of the LMZ in the station conditions, have been considered and analyzed and will provide an opportunity to assess the individual resource and continue the power unit operation. In the calculated assessment of changes in the thermal and stress-strain state of the HPC rotor, taking into account the data of the technical audit regarding damage, a geometric model of the rotor was created. Studies were conducted for three options of designs: the original option (five stages of the HPC rotor), the option without the blades of the last stage and the option without the fifth stage (with four first stages). For the project design, when working at the nominal parameters of the steam, the most stressed areas are the unloading holes of the 5th stage (σi=202.8 MPa), axial hole of the rotor in the area of the 5th stage (σi=195.2 MPa), as well as the 5th-degree welding fillet from the side of the end seals (σi=200.3 MPa) and unloading holes of the 4th and 3rd stages with a stress intensity of about 170–185 MPa. The high values of the stress intensity in the area of the 5th stage can be explained by the significant concentration of the mass of both the stage itself and its blades, which provoke significant centrifugal forces when working at the nominal rotation frequency. For a HPC rotor without blades of the 5th stage, there is a shift of the maximum stress intensity to the area of the unloading holes of the 4th and 3rd stages, as well as the axial hole of the shaft under the same stages. The maximum stress value is σi max=184.8 MPa. At the same time, the intensity of stresses in the area of unloading holes of the 5th degree decreased almost by half, to the level of 124 MPa.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.006
Andrii V. Rusanov, Valerii S. Fedoreiko, Dariusz Kardaś, Andrii O. Kostikov, Viktoriia O. Tarasova, Roman A. Rusanov, Maryna O. Chuhai, Mykhailo I. Sukhanov, Serhii P. Tretiak
The thermal scheme of a power generating plant with a remote heat exchanger operating according to the Brayton cycle with energy recuperation is considered. It is assumed that the plant will work on non-certified (cheap) biofuel. It is shown that, in contrast to the usual Brayton cycle, in the cycle with energy recuperation, the greatest influence on the thermal efficiency is the heating temperature of the working medium and the internal efficiency of the main components of the plant, such as the compressor and the turbine. Also, in contrast to the usual Brayton cycle, a higher efficiency of the plant is achieved with smaller degrees of pressure reduction (increase) in the turbine (compressor). It was established that even at a relatively low temperature of the working medium heating (500 ºC), with high efficiency of the compressor and turbine, it is possible to achieve good characteristics of the power plant as a whole. At a temperature of up to 850 ºC, a thermal efficiency of 40% is achieved, but in this case the cost of materials and production increases. For a final conclusion about the possibility of using the proposed plant and its efficiency, it is necessary to conduct additional studies, in particular, of its main elements, such as a compressor, turbine, heat exchanger and others.
{"title":"Analysis of the Efficiency of a Power Generating Plant Operating on the Basis of the Brayton Thermodynamic Cycle and Energy Recuperation","authors":"Andrii V. Rusanov, Valerii S. Fedoreiko, Dariusz Kardaś, Andrii O. Kostikov, Viktoriia O. Tarasova, Roman A. Rusanov, Maryna O. Chuhai, Mykhailo I. Sukhanov, Serhii P. Tretiak","doi":"10.15407/pmach2023.03.006","DOIUrl":"https://doi.org/10.15407/pmach2023.03.006","url":null,"abstract":"The thermal scheme of a power generating plant with a remote heat exchanger operating according to the Brayton cycle with energy recuperation is considered. It is assumed that the plant will work on non-certified (cheap) biofuel. It is shown that, in contrast to the usual Brayton cycle, in the cycle with energy recuperation, the greatest influence on the thermal efficiency is the heating temperature of the working medium and the internal efficiency of the main components of the plant, such as the compressor and the turbine. Also, in contrast to the usual Brayton cycle, a higher efficiency of the plant is achieved with smaller degrees of pressure reduction (increase) in the turbine (compressor). It was established that even at a relatively low temperature of the working medium heating (500 ºC), with high efficiency of the compressor and turbine, it is possible to achieve good characteristics of the power plant as a whole. At a temperature of up to 850 ºC, a thermal efficiency of 40% is achieved, but in this case the cost of materials and production increases. For a final conclusion about the possibility of using the proposed plant and its efficiency, it is necessary to conduct additional studies, in particular, of its main elements, such as a compressor, turbine, heat exchanger and others.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-30DOI: 10.15407/pmach2023.03.033
Anatolii O. Tarelin, Oleh Weres
The paper deals with comprehensive research in the field of electrization of wet steam flow in a turbine. The experience of the conducted studies on laboratory stands and full-scale objects (CHP and TPP) in Ukraine and the USA is introduced and generalized. It was shown that in the process of steam electrization, the charge density in the flow can reach very high values (an order of magnitude appears to be higher than in a thundercloud), and this phenomenon mainly has a negative effect on the turbine operation. Statistical data on the charge formation of the steam flow in the low-pressure cylinder of the turbine are presented. Results of the research to establish the main electrophysical factors of influence on the surface strength of the blade, such as electric fields, charge density and their polarity, are presented. The research results showed that such factors as the presence of a positively charged steam flow, constant and variable electric fields, which were most often recorded at operating turbines of CHPs and TPPs, significantly (by two or more times) intensify erosion-corrosion processes on the metal surfaces of the blades, thus reducing their working resource. Thermodynamic processes are studied both under conditions of natural electrification of a high-speed flow, which reduce the efficiency by about 0.3–0.35%, and under the influence of artificially created electric charges, which make it possible to increase the efficiency of the steam expansion process in the turbine by 2 or more percent. Various options of local input of electrical energy for steam ionization in the turbine are considered. At the same time, it is noted that for the practical implementation of these approaches, further careful design improvements and tests on model and full-scale installations are required. Water chemistry regimes are also considered in the context of their influence on the flow charge formation process, as well as on reliability and efficiency indicators of the turbine. Experimentally at an 800 MW turbine plant in the USA, it was shown that a change in the pH of the medium affects the intensity and polarity of the charge formation of the steam flow. The paper introduces the physical features of this phenomenon and notes the importance of these processes influence on the strength characteristics of the blades. Information on new methods and technologies that could lead to an increase in the operational efficiency and reliability of wet steam turbines, such as methods for input and removal of electrical energy into the flow; rational choice of water chemistry regimes; space charge neutralization, etc., is provided. These comprehensive electrophysical studies, considered in conjunction with thermal processes, can be characterized as a new scientific direction in the theory of steam turbines – thermal electrophysics.
{"title":"Integrated Studies of Electrophysical Processes in Steam Turbines","authors":"Anatolii O. Tarelin, Oleh Weres","doi":"10.15407/pmach2023.03.033","DOIUrl":"https://doi.org/10.15407/pmach2023.03.033","url":null,"abstract":"The paper deals with comprehensive research in the field of electrization of wet steam flow in a turbine. The experience of the conducted studies on laboratory stands and full-scale objects (CHP and TPP) in Ukraine and the USA is introduced and generalized. It was shown that in the process of steam electrization, the charge density in the flow can reach very high values (an order of magnitude appears to be higher than in a thundercloud), and this phenomenon mainly has a negative effect on the turbine operation. Statistical data on the charge formation of the steam flow in the low-pressure cylinder of the turbine are presented. Results of the research to establish the main electrophysical factors of influence on the surface strength of the blade, such as electric fields, charge density and their polarity, are presented. The research results showed that such factors as the presence of a positively charged steam flow, constant and variable electric fields, which were most often recorded at operating turbines of CHPs and TPPs, significantly (by two or more times) intensify erosion-corrosion processes on the metal surfaces of the blades, thus reducing their working resource. Thermodynamic processes are studied both under conditions of natural electrification of a high-speed flow, which reduce the efficiency by about 0.3–0.35%, and under the influence of artificially created electric charges, which make it possible to increase the efficiency of the steam expansion process in the turbine by 2 or more percent. Various options of local input of electrical energy for steam ionization in the turbine are considered. At the same time, it is noted that for the practical implementation of these approaches, further careful design improvements and tests on model and full-scale installations are required. Water chemistry regimes are also considered in the context of their influence on the flow charge formation process, as well as on reliability and efficiency indicators of the turbine. Experimentally at an 800 MW turbine plant in the USA, it was shown that a change in the pH of the medium affects the intensity and polarity of the charge formation of the steam flow. The paper introduces the physical features of this phenomenon and notes the importance of these processes influence on the strength characteristics of the blades. Information on new methods and technologies that could lead to an increase in the operational efficiency and reliability of wet steam turbines, such as methods for input and removal of electrical energy into the flow; rational choice of water chemistry regimes; space charge neutralization, etc., is provided. These comprehensive electrophysical studies, considered in conjunction with thermal processes, can be characterized as a new scientific direction in the theory of steam turbines – thermal electrophysics.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135040569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.24191/jmeche.v20i3.23903
Ali Meftah Meftah
In this article, functionally graded plates’ buckling and bending analyses are investigated using a new shape function. The parabolic transverse shear stresses throughout the thickness are regarded by this function as meeting the shear stress-free surface conditions and enabling an accurate distribution of shear deformation according to the thickness of the plate without integrating shear correction factors. Compared to previous shear theories, this higher-order shear theory has the fewest unknowns. The equations for the functionally graded plates are produced by employing the Hamiltonian principle, and the solutions are obtained using Napier’s technique. The outcomes of the current analysis are provided and contrasted with those found in the literature.
{"title":"Bending and Buckling Analysis of Functionally Graded Plates using a New Shear Strain Function with Reduced Unknowns","authors":"Ali Meftah Meftah","doi":"10.24191/jmeche.v20i3.23903","DOIUrl":"https://doi.org/10.24191/jmeche.v20i3.23903","url":null,"abstract":"In this article, functionally graded plates’ buckling and bending analyses are investigated using a new shape function. The parabolic transverse shear stresses throughout the thickness are regarded by this function as meeting the shear stress-free surface conditions and enabling an accurate distribution of shear deformation according to the thickness of the plate without integrating shear correction factors. Compared to previous shear theories, this higher-order shear theory has the fewest unknowns. The equations for the functionally graded plates are produced by employing the Hamiltonian principle, and the solutions are obtained using Napier’s technique. The outcomes of the current analysis are provided and contrasted with those found in the literature.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135485923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.24191/jmeche.v20i3.23909
Norfauzi Tamin
This study introduces the effect of ceramic composition that consists of Alumina (Al2O3)-Zirconia (ZrO2)-Chromia (Cr2O3) compositions on agglomerate and shrinkage for cutting tool development. Shrinkage is a problem in the development of ceramic cutting tools other than the occurrence of particle agglomerate on the body structure. Finer grain size significantly contributes to the ceramic body's shrinkage and agglomeration. This study analyzed grain size and its relationship with shrinkage and agglomerates. The powders were ball-milled with 80 wt% Al2O3 -20 wt% ZrO2 -0.6 wt% Cr2O3 and then compacted and sintered at 1400 °C to examine their shrinkage and investigate microstructure by scanning electron microscopy (SEM) machine. The results show that ZrO2 has a larger particle size of 6.10 μm and Cr2O3 has a finer measure of 1.24 μm. When blended with the ball mill, the mix of Al2O3- ZrO2-Cr2O3 was obtained is 7.30 μm, showing that the ball mill can uniformly mix all the particles and reduce the risk of agglomeration. The microstructural analysis found that Cr2O3 covers and fills up the space between Al2O3 and ZrO2 compared to without Cr2O3. The combination of agglomerate and shrinkage of Al2O3-ZrO2-Cr2O3 was responsible for the performance of the ceramic cutting tool fabricated.
{"title":"Reducing The Risk of Agglomeration and Shrinkage Ceramic Body from Al2O3-ZrO2 Composition","authors":"Norfauzi Tamin","doi":"10.24191/jmeche.v20i3.23909","DOIUrl":"https://doi.org/10.24191/jmeche.v20i3.23909","url":null,"abstract":"This study introduces the effect of ceramic composition that consists of Alumina (Al2O3)-Zirconia (ZrO2)-Chromia (Cr2O3) compositions on agglomerate and shrinkage for cutting tool development. Shrinkage is a problem in the development of ceramic cutting tools other than the occurrence of particle agglomerate on the body structure. Finer grain size significantly contributes to the ceramic body's shrinkage and agglomeration. This study analyzed grain size and its relationship with shrinkage and agglomerates. The powders were ball-milled with 80 wt% Al2O3 -20 wt% ZrO2 -0.6 wt% Cr2O3 and then compacted and sintered at 1400 °C to examine their shrinkage and investigate microstructure by scanning electron microscopy (SEM) machine. The results show that ZrO2 has a larger particle size of 6.10 μm and Cr2O3 has a finer measure of 1.24 μm. When blended with the ball mill, the mix of Al2O3- ZrO2-Cr2O3 was obtained is 7.30 μm, showing that the ball mill can uniformly mix all the particles and reduce the risk of agglomeration. The microstructural analysis found that Cr2O3 covers and fills up the space between Al2O3 and ZrO2 compared to without Cr2O3. The combination of agglomerate and shrinkage of Al2O3-ZrO2-Cr2O3 was responsible for the performance of the ceramic cutting tool fabricated.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.24191/jmeche.v20i3.23913
Mohd Firdaus Malek
Zinc oxide nanowires (ZnO NWs) have been successfully synthesized via a hybrid microwave-assisted sonochemical technique (HMAST) using zinc acetate dehydrate as starting material. The optimized parameters were set at 12.5 mM solution concentration and a rapid deposition time of 60 minutes. The microwave power was varied from 100 to 800 Watts and the effect of microwave power on the morphological, structural, and optical properties ofthe ZnO NWs has also been studied. Results showed an aligned, uniformly distributed hexagonal wurtzite structure of ZnO NWs was produced, which were augmented at 600 W microwave power, having the smallest diameter size of 29.66 nm. The XRD graph showed that the ZnO NWs produced are highly crystalline, exhibiting the sharpest and narrowest intensity of (002) peaks and a crystallite size of 18.60 nm. The transmittance spectra obtained by UV-Vis would be 89.72%, having a sharp absorption edge, implying the lower particle size of ZnO as well as exhibiting high absorbance in the ultraviolet region, indicating good crystallinity. From the findings, it can be confirmed that the microwave-assisted method helped in improving the formation of higher quality ZnO NWs that can be befittingly applied in many devices such as photocatalysts and sensors due to their excellent electrochemical properties.
{"title":"Synthesisation of Zinc Oxide Nanowires via Hybrid Microwave-Assisted Sonochemical Technique at Various Microwave Power","authors":"Mohd Firdaus Malek","doi":"10.24191/jmeche.v20i3.23913","DOIUrl":"https://doi.org/10.24191/jmeche.v20i3.23913","url":null,"abstract":"Zinc oxide nanowires (ZnO NWs) have been successfully synthesized via a hybrid microwave-assisted sonochemical technique (HMAST) using zinc acetate dehydrate as starting material. The optimized parameters were set at 12.5 mM solution concentration and a rapid deposition time of 60 minutes. The microwave power was varied from 100 to 800 Watts and the effect of microwave power on the morphological, structural, and optical properties ofthe ZnO NWs has also been studied. Results showed an aligned, uniformly distributed hexagonal wurtzite structure of ZnO NWs was produced, which were augmented at 600 W microwave power, having the smallest diameter size of 29.66 nm. The XRD graph showed that the ZnO NWs produced are highly crystalline, exhibiting the sharpest and narrowest intensity of (002) peaks and a crystallite size of 18.60 nm. The transmittance spectra obtained by UV-Vis would be 89.72%, having a sharp absorption edge, implying the lower particle size of ZnO as well as exhibiting high absorbance in the ultraviolet region, indicating good crystallinity. From the findings, it can be confirmed that the microwave-assisted method helped in improving the formation of higher quality ZnO NWs that can be befittingly applied in many devices such as photocatalysts and sensors due to their excellent electrochemical properties.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.24191/jmeche.v20i3.23912
The traditional fishing vessels in Indonesia are usually made of wood material. The weakness of this vessel material is that it is easily weathered when exposed to seawater. For this reason, it is necessary to have vessel material engineering from composite sandwiches. This study aimed to prepare and investigate the flexural test, impact test, optical microscopy (OM), and scanning electron microscopy (SEM) observations of sandwich composites based on coconut fibre-polyester resin and wood core. The fabrication uses a hand lay-up method with a constant volume fraction (20% coconut coir fibre) and wood core variations type. The primary wood variations used are albizia chinensis, mahogany, shorea, and camphor. The Surface modification of fibre and wood core was conditioned without treatment and with treatment with about 5% NaOH solution for 2 hours. The study showed that the highest bending and impact strength was sandwich composite with camphor wood cores with alkali treatment for 39.75 MPa and 37.22 J/cm2, respectively. The OM observations showed that the core and skin interface area failed to delaminate after flexural and impact tests. SEM observations also showed thatthe bond alkalization treatment between the matrix and the fibres was quite good. In the composite skin fracture area, there is a lot of fibre brake, and a little thread pulls out. The skin matrix also shows the presence of voids. Generally, this sandwich composite is feasible for application as a material for traditional fishing vessels.
{"title":"The Characterization of the Sandwich Composite Consisted of Coconut Fibre-Polyester Resin and its Variations of Wood Core","authors":"","doi":"10.24191/jmeche.v20i3.23912","DOIUrl":"https://doi.org/10.24191/jmeche.v20i3.23912","url":null,"abstract":"The traditional fishing vessels in Indonesia are usually made of wood material. The weakness of this vessel material is that it is easily weathered when exposed to seawater. For this reason, it is necessary to have vessel material engineering from composite sandwiches. This study aimed to prepare and investigate the flexural test, impact test, optical microscopy (OM), and scanning electron microscopy (SEM) observations of sandwich composites based on coconut fibre-polyester resin and wood core. The fabrication uses a hand lay-up method with a constant volume fraction (20% coconut coir fibre) and wood core variations type. The primary wood variations used are albizia chinensis, mahogany, shorea, and camphor. The Surface modification of fibre and wood core was conditioned without treatment and with treatment with about 5% NaOH solution for 2 hours. The study showed that the highest bending and impact strength was sandwich composite with camphor wood cores with alkali treatment for 39.75 MPa and 37.22 J/cm2, respectively. The OM observations showed that the core and skin interface area failed to delaminate after flexural and impact tests. SEM observations also showed thatthe bond alkalization treatment between the matrix and the fibres was quite good. In the composite skin fracture area, there is a lot of fibre brake, and a little thread pulls out. The skin matrix also shows the presence of voids. Generally, this sandwich composite is feasible for application as a material for traditional fishing vessels.","PeriodicalId":16332,"journal":{"name":"Journal of Mechanical Engineering","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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