The current work is being done to investigate the flow of nanofluids across a porous exponential stretching surface in the presence of a heat source/sink, thermophoretic particle deposition, and bioconvection. The collection of PDEs (partial differential equations) that represent the fluid moment is converted to a system of ODEs (ordinary differential equations) with the use of suitable similarity variables, and these equations are then numerically solved using Runge Kutta Fehlberg and the shooting approach. For different physical limitations, the numerical results are visually represented. The results show that increasing the porosity characteristics reduces velocity. The mass transfer decreases as the thermophoretic limitation increases. Increases in the porosity parameter reduce skin friction, increases in the solid volume fraction improve the rate of thermal distribution, and increases in the thermophoretic parameter increase the rate of mass transfer.
{"title":"Bioconvective nanofluid flow over an exponential stretched sheet with thermophoretic particle deposition","authors":"B.C. Prasannakumara , J.K. Madhukesh , G.K. Ramesh","doi":"10.1016/j.jppr.2023.05.004","DOIUrl":"10.1016/j.jppr.2023.05.004","url":null,"abstract":"<div><p>The current work is being done to investigate the flow of nanofluids across a porous exponential stretching surface in the presence of a heat source/sink, thermophoretic particle deposition, and bioconvection. The collection of PDEs (partial differential equations) that represent the fluid moment is converted to a system of ODEs (ordinary differential equations) with the use of suitable similarity variables, and these equations are then numerically solved using Runge Kutta Fehlberg and the shooting approach. For different physical limitations, the numerical results are visually represented. The results show that increasing the porosity characteristics reduces velocity. The mass transfer decreases as the thermophoretic limitation increases. Increases in the porosity parameter reduce skin friction, increases in the solid volume fraction improve the rate of thermal distribution, and increases in the thermophoretic parameter increase the rate of mass transfer.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 2","pages":"Pages 284-296"},"PeriodicalIF":5.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42270784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-01DOI: 10.1016/j.jppr.2023.02.005
B. Kumar , Prachi , Abhinav Singhal , R. Nandkeolyar , Pulkit Kumar , Ali J. Chamkha
This article elucidates the impact of activation energy on magnetohydrodynamic (MHD) stagnation point nanofluid flow over a slippery surface in a porous regime with thermophoretic and Brownian diffusions. Negative activation energy is scarce in practice, but the impact of negative activation energy could not be neglected as it is noticed in chemical processes. The rate of some Arrhenius-compliant reactions is retarded by increasing the temperature and is therefore associated with negative activation energies, such as exothermic binding of urea or water. In some processes, the temperature dependence of the pressure-induced unfolding and the urea-induced unfolding of proteins at ambient pressure give negative activation energies. The present mathematical model is solved with successive linearization method (a spectral technique). A comparison of results is made for negative and positive values of activation energy. Apart from it, the quadratic multiple regression model is discussed briefly and explained with bar diagrams. It is observed that with rise in unsteadiness parameter from 0 to 1 (taking positive activation energy), skin friction and Sherwood number are increased by 9.36 and 19 respectively, and Nusselt number is decreased by 26. However, for negative activation energy, 9.36 and 112 enhancement is observed in skin friction and Sherwood number, respectively.
{"title":"Regression analysis and features of negative activation energy for MHD nanofluid flow model: A comparative study","authors":"B. Kumar , Prachi , Abhinav Singhal , R. Nandkeolyar , Pulkit Kumar , Ali J. Chamkha","doi":"10.1016/j.jppr.2023.02.005","DOIUrl":"10.1016/j.jppr.2023.02.005","url":null,"abstract":"<div><p>This article elucidates the impact of activation energy on magnetohydrodynamic (MHD) stagnation point nanofluid flow over a slippery surface in a porous regime with thermophoretic and Brownian diffusions. Negative activation energy is scarce in practice, but the impact of negative activation energy could not be neglected as it is noticed in chemical processes. The rate of some Arrhenius-compliant reactions is retarded by increasing the temperature and is therefore associated with negative activation energies, such as exothermic binding of urea or water. In some processes, the temperature dependence of the pressure-induced unfolding and the urea-induced unfolding of proteins at ambient pressure give negative activation energies. The present mathematical model is solved with successive linearization method (a spectral technique). A comparison of results is made for negative and positive values of activation energy. Apart from it, the quadratic multiple regression model is discussed briefly and explained with bar diagrams. It is observed that with rise in unsteadiness parameter from 0 to 1 (taking positive activation energy), skin friction and Sherwood number are increased by 9.36<span><math><mrow><mo>%</mo></mrow></math></span> and 19<span><math><mrow><mo>%</mo></mrow></math></span> respectively, and Nusselt number is decreased by 26<span><math><mrow><mo>%</mo></mrow></math></span>. However, for negative activation energy, 9.36<span><math><mrow><mo>%</mo></mrow></math></span> and 112<span><math><mrow><mo>%</mo></mrow></math></span> enhancement is observed in skin friction and Sherwood number, respectively.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 2","pages":"Pages 273-283"},"PeriodicalIF":5.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49402259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-01DOI: 10.1016/j.jppr.2023.02.007
Sohail Rehman , Hashim , Fuad A.M. Al-Yarimi , Sultan Alqahtani , Mohammed Awad
The current article communicates a numerical investigation on laminar flow of dissipative generalized Newtonian Carreau nanofluid flowing through vertical conduit with converging and diverging plane walls. Thermal and concentration characteristics due to enthalpy change, activation energy, and non-linear thermal radiation have been examined in the presence of buoyancy forces. The channel walls for both temperature and volumetric fraction are assumed to be isothermal. The instability mechanism of nanofluids is reported using a two-phase nanofluid model, which works reasonably well for nanoparticle concentrations below a certain threshold. A Jeffery-Hamel (J-H) flow model is developed by assuming an incompressible purely radial flow of Carreau nanofluids with heat and mass transportation. Using the suitable non-dimensional variables, the resulting nonlinear partial differential equations are turned into a system of ordinary differential equations. The modified governing equations are then numerically solved using the built-in boundary value problem solver bvp4c, on the template form of commercial software MATLAB. The impacts of material, geometrical and thermophysical parameters governing the J-H problem are discussed and illustrated. Results indicate that higher buoyance forces incline the velocity profiles in converging enclosure, while a slight reduction is perceived in opposing forces. A significant decrease of wall heat transmission is reflected for larger values of activation energy and radiation parameter. For endorsing this communication, a comparison analysis is established with existing research and noticed a remarkable agreement. Practically, the flow inside converging and diverging channels are deployed in nuclear reactors that use plate-type nuclear energies, high heat-flux condensed heat exchangers, high-performance micro-electronic cooling systems, jets, rockets nozzles, and jet propulsion inlet.
{"title":"Dissipative flow features of Carreau nanofluid with thermal radiation inside plane wall channel: Jeffery-Hamel analysis","authors":"Sohail Rehman , Hashim , Fuad A.M. Al-Yarimi , Sultan Alqahtani , Mohammed Awad","doi":"10.1016/j.jppr.2023.02.007","DOIUrl":"10.1016/j.jppr.2023.02.007","url":null,"abstract":"<div><p>The current article communicates a numerical investigation on laminar flow of dissipative generalized Newtonian Carreau nanofluid flowing through vertical conduit with converging and diverging plane walls. Thermal and concentration characteristics due to enthalpy change, activation energy, and non-linear thermal radiation have been examined in the presence of buoyancy forces. The channel walls for both temperature and volumetric fraction are assumed to be isothermal. The instability mechanism of nanofluids is reported using a two-phase nanofluid model, which works reasonably well for nanoparticle concentrations below a certain threshold. A Jeffery-Hamel (J-H) flow model is developed by assuming an incompressible purely radial flow of Carreau nanofluids with heat and mass transportation. Using the suitable non-dimensional variables, the resulting nonlinear partial differential equations are turned into a system of ordinary differential equations. The modified governing equations are then numerically solved using the built-in boundary value problem solver bvp4c, on the template form of commercial software MATLAB. The impacts of material, geometrical and thermophysical parameters governing the J-H problem are discussed and illustrated. Results indicate that higher buoyance forces incline the velocity profiles in converging enclosure, while a slight reduction is perceived in opposing forces. A significant decrease of wall heat transmission is reflected for larger values of activation energy and radiation parameter. For endorsing this communication, a comparison analysis is established with existing research and noticed a remarkable agreement. Practically, the flow inside converging and diverging channels are deployed in nuclear reactors that use plate-type nuclear energies, high heat-flux condensed heat exchangers, high-performance micro-electronic cooling systems, jets, rockets nozzles, and jet propulsion inlet.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 2","pages":"Pages 253-272"},"PeriodicalIF":5.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49622471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-01DOI: 10.1016/j.jppr.2022.11.003
Yash Pal , Sasi Kiran Palateerdham , Sri Nithya Mahottamananda , Subha Sivakumar , Antonella Ingenito
Paraffin-based fuel has a great potential for several innovative missions, including space tourism, due to its safety, low environmental impact, high performance and low cost. Despite the fact that liquefying solid fuels increases the regression rate of hybrid rocket motors, incorporating energetic materials into solid fuel can still improve the performance. The objective and scope of this study is to increase the performance characteristics of the paraffin-based fuel by using magnesium diboride (MgB2) and carbon black (CB) additives. The cylindrical-port fuel grains were manufactured with various additives percentages in mass (wt%: CB-2% and MgB2-10%) and tested using a laboratory-scale ballistic hybrid motor under gaseous oxygen. The mechanical performance results revealed that adding CB and MgB2 improved the ultimate strength and elastic modulus of paraffin-based fuels. The addition of these fillers increased the hardness of fuel by developing a strong interaction in the paraffin matrix. Thermogravimetry (TG) results showed that CB inclusion improved the thermal stability of the paraffin matrix. The average regression rates of fuels loaded with CB and MgB2 were 32% and 52% higher than those of unmodified paraffin wax, respectively. The characteristic velocity efficiency was found in the range of 68%–79% at an O/F ratio of 1.5–2.6. The MgB2 oxidation/combustion in the paraffin matrix was described by a four-step oxidation process ranging from 473 K to 1723 K. Finally, a combustion model of MgB2 in the paraffin matrix was proposed, and four-step oxidation processes were discussed in detail.
{"title":"Combustion performance of hybrid rocket fuels loaded with MgB2 and carbon black additives","authors":"Yash Pal , Sasi Kiran Palateerdham , Sri Nithya Mahottamananda , Subha Sivakumar , Antonella Ingenito","doi":"10.1016/j.jppr.2022.11.003","DOIUrl":"10.1016/j.jppr.2022.11.003","url":null,"abstract":"<div><p>Paraffin-based fuel has a great potential for several innovative missions, including space tourism, due to its safety, low environmental impact, high performance and low cost. Despite the fact that liquefying solid fuels increases the regression rate of hybrid rocket motors, incorporating energetic materials into solid fuel can still improve the performance. The objective and scope of this study is to increase the performance characteristics of the paraffin-based fuel by using magnesium diboride (MgB<sub>2</sub>) and carbon black (CB) additives. The cylindrical-port fuel grains were manufactured with various additives percentages in mass (wt%: CB-2% and MgB<sub>2</sub>-10%) and tested using a laboratory-scale ballistic hybrid motor under gaseous oxygen. The mechanical performance results revealed that adding CB and MgB<sub>2</sub> improved the ultimate strength and elastic modulus of paraffin-based fuels. The addition of these fillers increased the hardness of fuel by developing a strong interaction in the paraffin matrix. Thermogravimetry (TG) results showed that CB inclusion improved the thermal stability of the paraffin matrix. The average regression rates of fuels loaded with CB and MgB<sub>2</sub> were 32% and 52% higher than those of unmodified paraffin wax, respectively. The characteristic velocity efficiency was found in the range of 68%–79% at an O/F ratio of 1.5–2.6. The MgB<sub>2</sub> oxidation/combustion in the paraffin matrix was described by a four-step oxidation process ranging from 473 K to 1723 K. Finally, a combustion model of MgB<sub>2</sub> in the paraffin matrix was proposed, and four-step oxidation processes were discussed in detail.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 2","pages":"Pages 212-226"},"PeriodicalIF":5.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47416402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Regenerative cooling by endothermic hydrocarbon fuel (EHF) is one of the most promising techniques for thermal management of supersonic or hypersonic aircraft. How to maintain the fuel working in proper states is an important issue to maximize the cooling potential of EHT. This work proposes a novel working state map, including risking zone (RZ), thermal cracking zone (TCZ), supercritical zone (SupZ) and subcritical zone (SubZ), to differentiate possible working states of an EHF during regenerative cooling. Using n-decane flowing in a circular tube as an example, the boundaries of four zones are determined by numerical simulation covering different heat fluxes (0.2–4.0 MW·m−2) and mass flow rates (0.5–10.5 g·s−1) under two operating pressures (3.45 and 5.00 MPa). Empirical correlations for three boundary lines are obtained and the maximum cooling capacity is identified, as well as the identification of the pressure effect. The revelation of such new perspective of regenerative cooling is of great implication to the design and optimization of cooling system for future thermal management.
{"title":"Working state map of hydrocarbon fuels for regenerative cooling","authors":"Chen Zhang , Hui Gao , Jiajun Zhao , Guice Yao , Dongsheng Wen","doi":"10.1016/j.jppr.2023.05.002","DOIUrl":"10.1016/j.jppr.2023.05.002","url":null,"abstract":"<div><p>Regenerative cooling by endothermic hydrocarbon fuel (EHF) is one of the most promising techniques for thermal management of supersonic or hypersonic aircraft. How to maintain the fuel working in proper states is an important issue to maximize the cooling potential of EHT. This work proposes a novel working state map, including risking zone (RZ), thermal cracking zone (TCZ), supercritical zone (SupZ) and subcritical zone (SubZ), to differentiate possible working states of an EHF during regenerative cooling. Using <em>n</em>-decane flowing in a circular tube as an example, the boundaries of four zones are determined by numerical simulation covering different heat fluxes (0.2–4.0 MW<strong>·</strong>m<sup>−2</sup>) and mass flow rates (0.5–10.5 g<strong>·</strong>s<sup>−1</sup>) under two operating pressures (3.45 and 5.00 MPa). Empirical correlations for three boundary lines are obtained and the maximum cooling capacity is identified, as well as the identification of the pressure effect. The revelation of such new perspective of regenerative cooling is of great implication to the design and optimization of cooling system for future thermal management.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 2","pages":"Pages 199-211"},"PeriodicalIF":5.3,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41610458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-01DOI: 10.1016/j.jppr.2023.02.006
Junlong Zhang, Guangjun Feng, Haotian Bai, Kangshuai Lv, Wen Bao
Combustion characteristics in a scramjet combustor equipped with a thin strut were observed and discussed in this paper. A series of numerical simulations were carried out under different flight dynamic pressure conditions. The parameters of cold flow field and combustion field were used to analyze the combustion characteristics. Based on the basic data, the mixing efficiency, characteristics of flame establishment and propagation as well as combustion field characteristics were discussed in this paper. The influence laws of lower dynamic pressure conditions were further revealed to optimize combustor performance. Results indicated that properly reducing the flight dynamic pressure can enhance the mixing of kerosene. The diffusion of kerosene determined the distribution of combustion zone and heat release. Then, the influencing factor that affected the chemical reaction rate was revealed to shorten chemical reaction time. And the higher flight Mach number made the flame propagation velocity faster and the combustion stability stronger. The fuel mixing became the main factor and low dynamic pressure had little effect on laminar flame propagation velocity under high Mach number conditions. The investigations in this paper are helpful for understanding the combustion characteristics under low dynamic pressure conditions.
{"title":"Research on combustion characteristics of scramjet combustor with different flight dynamic pressure conditions","authors":"Junlong Zhang, Guangjun Feng, Haotian Bai, Kangshuai Lv, Wen Bao","doi":"10.1016/j.jppr.2023.02.006","DOIUrl":"10.1016/j.jppr.2023.02.006","url":null,"abstract":"<div><p>Combustion characteristics in a scramjet combustor equipped with a thin strut were observed and discussed in this paper. A series of numerical simulations were carried out under different flight dynamic pressure conditions. The parameters of cold flow field and combustion field were used to analyze the combustion characteristics. Based on the basic data, the mixing efficiency, characteristics of flame establishment and propagation as well as combustion field characteristics were discussed in this paper. The influence laws of lower dynamic pressure conditions were further revealed to optimize combustor performance. Results indicated that properly reducing the flight dynamic pressure can enhance the mixing of kerosene. The diffusion of kerosene determined the distribution of combustion zone and heat release. Then, the influencing factor that affected the chemical reaction rate was revealed to shorten chemical reaction time. And the higher flight Mach number made the flame propagation velocity faster and the combustion stability stronger. The fuel mixing became the main factor and low dynamic pressure had little effect on laminar flame propagation velocity under high Mach number conditions. The investigations in this paper are helpful for understanding the combustion characteristics under low dynamic pressure conditions.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 1","pages":"Pages 69-82"},"PeriodicalIF":5.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49150958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-01DOI: 10.1016/j.jppr.2023.01.003
Adrian Ieta , Marius Chirita
Rotary ionic engines (RIEs) with multi-coaxial contra-rotating propellers (12.6 cm diameter) and their axial thrust are investigated in laboratory conditions, in air at atmospheric pressure, for the first time. The goal is to evaluate more advantageous configurations that may be scaled up and further help with development of rotary ionic drones. The propellers are designed with regular pin-emitter electrodes placed coaxially inside a cylindrical collector electrode. When high voltage is applied, propellers spin generating conventional axial thrust which is measured with an electronic scale in a “see-saw” setup. Up to 40 mN thrust was obtained in single propeller RIE at 2600 rpm, 0.34 mA, 37.5 kV, and an optimal collector electrode diameter of 17 cm. More thrust can be obtained with two and three propellers at constant current per propeller but at a decreased efficiency. Varying the axial propeller-separation showed that propeller-interaction is minimal above 5 cm. Thrust-to-power and thrust-to-current ratios were calculated and compared. We experimentally confirm here for the first time that within certain limits, the thrust-to-power variation can be assessed by the propeller kinetic energy-to-power ratio and also by the impedance of the gap (voltage-to-current ratio). A comparison of RIE arrays performance with one, two, and three coaxial propellers and the same total number of propellers per array (six) is also performed. RIE arrays with multi-coaxial propellers can provide larger thrust densities than single-propeller arrays. Also, arrays employing two coaxial propeller unit may be more weight effective.
{"title":"First thrust measurements in ionic multi-propeller rotational engines","authors":"Adrian Ieta , Marius Chirita","doi":"10.1016/j.jppr.2023.01.003","DOIUrl":"10.1016/j.jppr.2023.01.003","url":null,"abstract":"<div><p>Rotary ionic engines (RIEs) with multi-coaxial contra-rotating propellers (12.6 cm diameter) and their axial thrust are investigated in laboratory conditions, in air at atmospheric pressure, for the first time. The goal is to evaluate more advantageous configurations that may be scaled up and further help with development of rotary ionic drones. The propellers are designed with regular pin-emitter electrodes placed coaxially inside a cylindrical collector electrode. When high voltage is applied, propellers spin generating conventional axial thrust which is measured with an electronic scale in a “see-saw” setup. Up to 40 mN thrust was obtained in single propeller RIE at 2600 rpm, 0.34 mA, 37.5 kV, and an optimal collector electrode diameter of 17 cm. More thrust can be obtained with two and three propellers at constant current per propeller but at a decreased efficiency. Varying the axial propeller-separation showed that propeller-interaction is minimal above 5 cm. Thrust-to-power and thrust-to-current ratios were calculated and compared. We experimentally confirm here for the first time that within certain limits, the thrust-to-power variation can be assessed by the propeller kinetic energy-to-power ratio and also by the impedance of the gap (voltage-to-current ratio). A comparison of RIE arrays performance with one, two, and three coaxial propellers and the same total number of propellers per array (six) is also performed. RIE arrays with multi-coaxial propellers can provide larger thrust densities than single-propeller arrays. Also, arrays employing two coaxial propeller unit may be more weight effective.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 1","pages":"Pages 44-58"},"PeriodicalIF":5.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44837597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Experimental and computational analysis has been carried out by many researchers on supersonic cavity flow, but detailed analysis based on Rossiter's model still requires some insight. In the current study an open rectangular cavity with a length to depth ratio of 2 (L/D = 2) and Mach number at the inlet as 1.71, was considered as a baseline configuration for experimental analysis. Statistical techniques such as power spectral density (PSD), correlation, and overall sound pressure level (OASPL) were carried out on the unsteady pressure data, to analyze the aero-acoustic flow physics. High-speed schlieren images were processed to obtain spatially coherent modes by proper orthogonal decomposition (POD). The analysis was extended for different dimensions of subcavities on the aft, floor, and front wall. This detailed analysis of these configurations with different dimensions and combinations revealed the various flow features and mode frequencies in supersonic cavity. As the front wall subcavity act as a passive control device, reducing the overall sound pressure level inside the cavity whereas, the aft wall subcavity acts as a passive resonator with distinct harmonic fluid-resonant modes, a similar phenomenon was observed for floor subcavity at different locations. A novel method was employed to analyze Rossiter's model and its applicability in estimating experimental modes was verified, as it accurately predicted the dominant frequencies with a maximum of 2.74% uncertainty among all the configurations.
{"title":"Effects of multiple subcavities with floor subcavity in supersonic cavity flow","authors":"Priyansh Jain, Anbarasan Sekar, Aravind Vaidyanathan","doi":"10.1016/j.jppr.2023.02.003","DOIUrl":"10.1016/j.jppr.2023.02.003","url":null,"abstract":"<div><p>Experimental and computational analysis has been carried out by many researchers on supersonic cavity flow, but detailed analysis based on Rossiter's model still requires some insight. In the current study an open rectangular cavity with a length to depth ratio of 2 (<em>L/D</em> = 2) and Mach number at the inlet as 1.71, was considered as a baseline configuration for experimental analysis. Statistical techniques such as power spectral density (PSD), correlation, and overall sound pressure level (OASPL) were carried out on the unsteady pressure data, to analyze the aero-acoustic flow physics. High-speed schlieren images were processed to obtain spatially coherent modes by proper orthogonal decomposition (POD). The analysis was extended for different dimensions of subcavities on the aft, floor, and front wall. This detailed analysis of these configurations with different dimensions and combinations revealed the various flow features and mode frequencies in supersonic cavity. As the front wall subcavity act as a passive control device, reducing the overall sound pressure level inside the cavity whereas, the aft wall subcavity acts as a passive resonator with distinct harmonic fluid-resonant modes, a similar phenomenon was observed for floor subcavity at different locations. A novel method was employed to analyze Rossiter's model and its applicability in estimating experimental modes was verified, as it accurately predicted the dominant frequencies with a maximum of 2.74% uncertainty among all the configurations.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 1","pages":"Pages 114-137"},"PeriodicalIF":5.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45401917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the sample entropy algorithm in nonlinear dynamics, an improved sample entropy method is proposed in the aerodynamic system instability identification for the stall precursor detection based on the nonlinear feature extraction algorithm in an axial compressor. The sample entropy algorithm is an improved algorithm based on the approximate entropy algorithm, which quantifies the regularity and the predictability of data in time series. Combined with the spatial modes representing for the rotating stall in the circumferential direction, the recognition capacity of the sample entropy is displayed well on the detection of stall inception. The indications of rotating waves are extracted by the circumferential analysis from modal wave energy. The significant ascendant in the amplitude of the spatial mode is a pronounced feature well before the imminence of stall. Data processing with the spatial mode effectively avoids the problems of inaccurate identification of a single measuring point only depending on pressure. Due to the different selections of similarity tolerance, two kinds of sample entropy are obtained. The properties of the development process of the identification model show obvious mutation phenomena at the boundary of instability, which reveal the inherent characteristic in aerodynamic system. Then the dynamic difference quotient is computed according to the difference quotient criterion, after the smooth management by discrete wavelet. The rapid increase of difference quotient can be regarded as a significant feature of the system approaching the flow instability. It is proven that based on the principle of sample entropy algorithm, the nonlinear characteristic of rotating stall can be well described. The inception can be suggested by about 12–68 revolutions before the stall arrival. This prediction method presenting is accounted for the nonlinearity of the complex flow in stall, which is in a view of data fusion system of pressure for the spatial mode tracking.
{"title":"Aerodynamic system instability identification with sample entropy algorithm based on feature extraction","authors":"Mingming Zhang , Jia Zhang , Anping Hou , Aiguo Xia , Wei Tuo , Yongzhao Lv","doi":"10.1016/j.jppr.2022.02.004","DOIUrl":"10.1016/j.jppr.2022.02.004","url":null,"abstract":"<div><p>Based on the sample entropy algorithm in nonlinear dynamics, an improved sample entropy method is proposed in the aerodynamic system instability identification for the stall precursor detection based on the nonlinear feature extraction algorithm in an axial compressor. The sample entropy algorithm is an improved algorithm based on the approximate entropy algorithm, which quantifies the regularity and the predictability of data in time series. Combined with the spatial modes representing for the rotating stall in the circumferential direction, the recognition capacity of the sample entropy is displayed well on the detection of stall inception. The indications of rotating waves are extracted by the circumferential analysis from modal wave energy. The significant ascendant in the amplitude of the spatial mode is a pronounced feature well before the imminence of stall. Data processing with the spatial mode effectively avoids the problems of inaccurate identification of a single measuring point only depending on pressure. Due to the different selections of similarity tolerance, two kinds of sample entropy are obtained. The properties of the development process of the identification model show obvious mutation phenomena at the boundary of instability, which reveal the inherent characteristic in aerodynamic system. Then the dynamic difference quotient is computed according to the difference quotient criterion, after the smooth management by discrete wavelet. The rapid increase of difference quotient can be regarded as a significant feature of the system approaching the flow instability. It is proven that based on the principle of sample entropy algorithm, the nonlinear characteristic of rotating stall can be well described. The inception can be suggested by about 12–68 revolutions before the stall arrival. This prediction method presenting is accounted for the nonlinearity of the complex flow in stall, which is in a view of data fusion system of pressure for the spatial mode tracking.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 1","pages":"Pages 138-152"},"PeriodicalIF":5.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43082400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-01DOI: 10.1016/j.jppr.2022.11.002
Amit Kumar Pandey , Krishnendu Bhattacharyya , Anil Kumar Gautam , Sohita Rajput , Mani Shankar Mandal , Ali J. Chamkha , Dhananjay Yadav
The current research focuses the light on the characterization of buoyancy-driven non-linear mixed convection and non-linear radiation in a Newtonian flow over a non-linearly stretching vertical sheet, and this type of flow has useful applications in many industrial processes, such as the paper and pulp industry, polymer industry, electronic device cooling, solar collectors, gas turbine plants, and nuclear power. Using appropriate transformations, governing PDEs for non-linear mixed convection are reduced to higher-order non-linear ODEs and those are numerically solved. Along with tabular presentations of computed results, the graphical representations are generated to elucidate the effects of involved parameters on convection transport properties and their inter-relations. It demonstrates that flow velocity increases near the surface and decreases away from the surface as the non-linear convection parameter increases. Furthermore, increments in the thermal buoyancy, temperature ratio and non-linear radiation parameters result in the boost of velocity. The temperature decreases as linear and non-linear buoyancy-related parameters (non-linear convection and thermal buoyancy parameters) are of higher levels. In contrast, the temperature rises with two non-linear thermal radiation-related parameters (thermal ratio and non-linear radiation parameters). For greater values of the non-linear stretching related parameter, a lower velocity and a higher temperature are witnessed. The non-linear convection, thermal buoyancy, thermal ratio and non-linear radiation parameters contribute toward the reduction of the magnitude of surface-drag force and growth of the surface cooling rate. But, with the non-linearity in surface stretching there are significant percentage hikes of surface-drag force magnitude and surface cooling rate.
{"title":"Insight into the relationship between non-linear mixed convection and thermal radiation: The case of Newtonian fluid flow due to non-linear stretching","authors":"Amit Kumar Pandey , Krishnendu Bhattacharyya , Anil Kumar Gautam , Sohita Rajput , Mani Shankar Mandal , Ali J. Chamkha , Dhananjay Yadav","doi":"10.1016/j.jppr.2022.11.002","DOIUrl":"10.1016/j.jppr.2022.11.002","url":null,"abstract":"<div><p>The current research focuses the light on the characterization of buoyancy-driven non-linear mixed convection and non-linear radiation in a Newtonian flow over a non-linearly stretching vertical sheet, and this type of flow has useful applications in many industrial processes, such as the paper and pulp industry, polymer industry, electronic device cooling, solar collectors, gas turbine plants, and nuclear power. Using appropriate transformations, governing PDEs for non-linear mixed convection are reduced to higher-order non-linear ODEs and those are numerically solved. Along with tabular presentations of computed results, the graphical representations are generated to elucidate the effects of involved parameters on convection transport properties and their inter-relations. It demonstrates that flow velocity increases near the surface and decreases away from the surface as the non-linear convection parameter increases. Furthermore, increments in the thermal buoyancy, temperature ratio and non-linear radiation parameters result in the boost of velocity. The temperature decreases as linear and non-linear buoyancy-related parameters (non-linear convection and thermal buoyancy parameters) are of higher levels. In contrast, the temperature rises with two non-linear thermal radiation-related parameters (thermal ratio and non-linear radiation parameters). For greater values of the non-linear stretching related parameter, a lower velocity and a higher temperature are witnessed. The non-linear convection, thermal buoyancy, thermal ratio and non-linear radiation parameters contribute toward the reduction of the magnitude of surface-drag force and growth of the surface cooling rate. But, with the non-linearity in surface stretching there are significant percentage hikes of surface-drag force magnitude and surface cooling rate.</p></div>","PeriodicalId":51341,"journal":{"name":"Propulsion and Power Research","volume":"12 1","pages":"Pages 153-165"},"PeriodicalIF":5.3,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46036383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}