Pub Date : 2023-09-29DOI: 10.1177/09576509231194667
Yingying Zhang, Fan Yang
This paper provides an improved 1D mid-span program to quickly grasp the off-design characteristic of modern axial turbines. The improvements are mainly focused on cooling, diffuser and the calculation of choke condition. Disk cooling and blade cooling air mixing are considered in detail. A 1D diffuser model that considers the effects of area change, heat transfer, and friction is added so that a realistic boundary condition at the turbine outlet can be obtained. A choke routine that enables the assessment of choked flow up to limit load conditions is introduced to avoid the shortcoming that the calculation method fails to converge near or at the initial choking mass flow rate. Flexible modules for losses, deviation, and mixing models are built-in to increase the accuracy and versatility of the program. This work is of great value because few programs take cooling and diffuser into account in such detail when calculating turbine performance in the form of maps. The salient issues presented here deal first with the construction of the turbine performance prediction program. The validation of the code is first performed on public data for a five-stage low pressure turbine (LPT). The results show that the efficiency relative errors with the experimental value is in the range of −(0.11%−1.64%), which is within acceptable limits. Then, the performance of GE PG9351FA transonic axial turbine is estimated using this program. This industrial axial turbine is predicted for the first time in a form of turbine performance maps in open literature and the obtained performance map is very useful for the simulation of gas turbine.
{"title":"One dimensional approach to predict the performance of high pressure multi-stage axial turbine considering air cooling and diffuser performance","authors":"Yingying Zhang, Fan Yang","doi":"10.1177/09576509231194667","DOIUrl":"https://doi.org/10.1177/09576509231194667","url":null,"abstract":"This paper provides an improved 1D mid-span program to quickly grasp the off-design characteristic of modern axial turbines. The improvements are mainly focused on cooling, diffuser and the calculation of choke condition. Disk cooling and blade cooling air mixing are considered in detail. A 1D diffuser model that considers the effects of area change, heat transfer, and friction is added so that a realistic boundary condition at the turbine outlet can be obtained. A choke routine that enables the assessment of choked flow up to limit load conditions is introduced to avoid the shortcoming that the calculation method fails to converge near or at the initial choking mass flow rate. Flexible modules for losses, deviation, and mixing models are built-in to increase the accuracy and versatility of the program. This work is of great value because few programs take cooling and diffuser into account in such detail when calculating turbine performance in the form of maps. The salient issues presented here deal first with the construction of the turbine performance prediction program. The validation of the code is first performed on public data for a five-stage low pressure turbine (LPT). The results show that the efficiency relative errors with the experimental value is in the range of −(0.11%−1.64%), which is within acceptable limits. Then, the performance of GE PG9351FA transonic axial turbine is estimated using this program. This industrial axial turbine is predicted for the first time in a form of turbine performance maps in open literature and the obtained performance map is very useful for the simulation of gas turbine.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135195390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-09-23DOI: 10.1177/09576509231204026
Xiangyuan Zhu, Yiming Qiao, Changcheng Xie
In order to investigate the clocking effect on unsteady flow distortion in the vicinity of the tongue and hydraulic loss in the volute, experiments and numerical simulations were conducted with four different relative angular positions between the vane and tongue. Numerical results were validated against experimental data, which included measurements of pressure pulsation at the tongue and downstream of the tongue. The radial and circumferential velocities near the tongue at the diffuser-volute clearance were depicted by expanding the rotating surface, and comparisons were made under different diffuser positions to reveal the flow distortion affected by the clocking effect. Shear stress rates and total pressure distributions at the volute exit pipe were also depicted to study the flow loss in the volute affected by the flow pattern from the tongue. The findings show that the pressure fluctuation at the tongue and downstream of the tongue is significantly affected by the diffuser mounting position. The amplitude and intensity of pressure pulsation under θ d1 are clearly smaller than those at other diffuser positions. As the vane trailing edge approaches the tongue, the pressure gradient becomes very large, leading to the formation of a vortex at the tongue that promotes crowding effects and reverse flow occurring in the exit pipe. This, in turn, leads to deflection of the main flow in the volute, high velocity gradients, and subsequently large shear stress rates and hydraulic losses. When the diffuser is installed at θ d4 , the flow distortion and flow loss are improved.
{"title":"Numerical investigation of clocking effect on unsteady fluid flow in vicinity of tongue for centrifugal pump with vaned diffuser","authors":"Xiangyuan Zhu, Yiming Qiao, Changcheng Xie","doi":"10.1177/09576509231204026","DOIUrl":"https://doi.org/10.1177/09576509231204026","url":null,"abstract":"In order to investigate the clocking effect on unsteady flow distortion in the vicinity of the tongue and hydraulic loss in the volute, experiments and numerical simulations were conducted with four different relative angular positions between the vane and tongue. Numerical results were validated against experimental data, which included measurements of pressure pulsation at the tongue and downstream of the tongue. The radial and circumferential velocities near the tongue at the diffuser-volute clearance were depicted by expanding the rotating surface, and comparisons were made under different diffuser positions to reveal the flow distortion affected by the clocking effect. Shear stress rates and total pressure distributions at the volute exit pipe were also depicted to study the flow loss in the volute affected by the flow pattern from the tongue. The findings show that the pressure fluctuation at the tongue and downstream of the tongue is significantly affected by the diffuser mounting position. The amplitude and intensity of pressure pulsation under θ d1 are clearly smaller than those at other diffuser positions. As the vane trailing edge approaches the tongue, the pressure gradient becomes very large, leading to the formation of a vortex at the tongue that promotes crowding effects and reverse flow occurring in the exit pipe. This, in turn, leads to deflection of the main flow in the volute, high velocity gradients, and subsequently large shear stress rates and hydraulic losses. When the diffuser is installed at θ d4 , the flow distortion and flow loss are improved.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135961407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-09-22DOI: 10.1177/09576509231200293
Yu Wang, Hua Chen, Chao Li, Chao Ma
Due to their high pressure rises, the gas temperature of high-speed centrifugal compressors can be very high to the detriment of compressor aerodynamic performance. A water-cooled vaned diffuser technique is proposed to alleviate this problem. Compressor housing integrated water-cooling passages are employed to introduce cooling water to the vanes through holes near the vane centre. The technique was applied to a 180 mm turbocharger compressor running at the tip speed of 452 m/s, and numerical studies with conjugate heat transfer and fluid-structure thermal interaction were carried out to find the effects of the cooling to compressor performance and the mechanical stress of diffuser vanes. The results show that compressor efficiency is improved by the cooling, and the improvement increases as compressor mass flow reduces. At modest pressure ratios around 3.3, the maximum improvement of 1.09 percentage points is achieved using 30°C inlet water temperature. The cooling is found to significantly reduce the air temperature near diffuser passage solid walls, thus lead to more uniform air temperatures at compressor exit. The reduction of 1.33°C and 2.21°C in the diffuser outlet temperature have been found at 1.68 kg/s air mass flow with 70°C and 30°C water inlet temperature respectively. Moreover, the thermal stress in diffuser vanes is shown to be lower with the cooling.
{"title":"A numerical investigation of the effect of vaned diffuser water cooling on the internal flow field of a centrifugal compressor","authors":"Yu Wang, Hua Chen, Chao Li, Chao Ma","doi":"10.1177/09576509231200293","DOIUrl":"https://doi.org/10.1177/09576509231200293","url":null,"abstract":"Due to their high pressure rises, the gas temperature of high-speed centrifugal compressors can be very high to the detriment of compressor aerodynamic performance. A water-cooled vaned diffuser technique is proposed to alleviate this problem. Compressor housing integrated water-cooling passages are employed to introduce cooling water to the vanes through holes near the vane centre. The technique was applied to a 180 mm turbocharger compressor running at the tip speed of 452 m/s, and numerical studies with conjugate heat transfer and fluid-structure thermal interaction were carried out to find the effects of the cooling to compressor performance and the mechanical stress of diffuser vanes. The results show that compressor efficiency is improved by the cooling, and the improvement increases as compressor mass flow reduces. At modest pressure ratios around 3.3, the maximum improvement of 1.09 percentage points is achieved using 30°C inlet water temperature. The cooling is found to significantly reduce the air temperature near diffuser passage solid walls, thus lead to more uniform air temperatures at compressor exit. The reduction of 1.33°C and 2.21°C in the diffuser outlet temperature have been found at 1.68 kg/s air mass flow with 70°C and 30°C water inlet temperature respectively. Moreover, the thermal stress in diffuser vanes is shown to be lower with the cooling.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136060805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To improve the efficiency and extend the lifespan of the proton exchange membrane fuel cells (PEMFC), it is imperative to control PEMFC’s supply system effectively. A sliding mode controller (SMC) based on adaptive algebraic observer is designed to control the oxygen excess ratio and the pressure difference between the cathode and anode of PEMFC. First, a 9th order physical model of the PEMFC system is established including air supply system, hydrogen supply system and the stack, which is validated against the experimental data with the maximum output voltage error of 2.91%. Then, a SMC is designed based on the control-oriented PEMFC model. An adaptive algebraic observer for the estimation of the gas partial pressure is designed to be used in the SMC. Finally, simulation is conducted and results show that the performance of the designed SMC is superior than that of the PID controller in terms of the oxygen excess ratio settling time (1s less), the pressure difference settling time (50% less) and overshoot (0.5 kPa less).
{"title":"Multi-Objective sliding mode control of proton exchange membrane fuel cell system based on adaptive algebraic observer","authors":"Hao Jing, Tiexiong Huang, Cheng Li, Xiaodong Liu, Guangdi Hu, Chaoping Pang","doi":"10.1177/09576509231201995","DOIUrl":"https://doi.org/10.1177/09576509231201995","url":null,"abstract":"To improve the efficiency and extend the lifespan of the proton exchange membrane fuel cells (PEMFC), it is imperative to control PEMFC’s supply system effectively. A sliding mode controller (SMC) based on adaptive algebraic observer is designed to control the oxygen excess ratio and the pressure difference between the cathode and anode of PEMFC. First, a 9th order physical model of the PEMFC system is established including air supply system, hydrogen supply system and the stack, which is validated against the experimental data with the maximum output voltage error of 2.91%. Then, a SMC is designed based on the control-oriented PEMFC model. An adaptive algebraic observer for the estimation of the gas partial pressure is designed to be used in the SMC. Finally, simulation is conducted and results show that the performance of the designed SMC is superior than that of the PID controller in terms of the oxygen excess ratio settling time (1s less), the pressure difference settling time (50% less) and overshoot (0.5 kPa less).","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-09-08DOI: 10.1177/09576509231197881
Miguel Lança, João Gomes, Diogo Cabral
Bifacial photovoltaic cells can produce electricity from incoming solar radiation on both sides. These cells have a strong potential to reduce electricity generation costs and may play an important role in the energy system of the future. However, today, these cells are mostly deployed with one side receiving only ground reflection, which leads to a profound sub-optimal utilization of one of the sides of the bifacial cells. Concentration allows a better usage of the potential of bifacial cells, which can lead to a lower cost per kWh. However, concentration also adds complexity due to the higher temperatures reached which add the requirement of cooling in order to achieve higher outputs. This way, this paper focuses on the effectiveness of forced air circulation methods by comparing the thermal performance of three specific concentrating bi-facial collector designs. This paper developed a computational model, using ANSYS Fluent intending to assess the thermal performance of a covered concentrating collector with bifacial Photovoltaic (PV) cells. These results have then been validated by outdoor measurements. Results show that even a simple natural ventilation mechanism such as removing the side gable can effectively reduce the receiver temperature, thus resulting in favourable cell operation conditions when compared to the case of an airtight collector. Therefore, compared with a standard model, a decrease of 13.5% on the cell operating temperature was reported when the side gables are removed. However, when forced ventilation is apllied a 22.8% reduction on temperature is found compared to the standard air-tight model. The validated CFD model has proven to be a useful and robust tool for the thermal analysis of solar concentrating systems.
{"title":"Thermal performance of three concentrating collectors with bifacial photovoltaic cells part I – Experimental and computational fluid dynamics study","authors":"Miguel Lança, João Gomes, Diogo Cabral","doi":"10.1177/09576509231197881","DOIUrl":"https://doi.org/10.1177/09576509231197881","url":null,"abstract":"Bifacial photovoltaic cells can produce electricity from incoming solar radiation on both sides. These cells have a strong potential to reduce electricity generation costs and may play an important role in the energy system of the future. However, today, these cells are mostly deployed with one side receiving only ground reflection, which leads to a profound sub-optimal utilization of one of the sides of the bifacial cells. Concentration allows a better usage of the potential of bifacial cells, which can lead to a lower cost per kWh. However, concentration also adds complexity due to the higher temperatures reached which add the requirement of cooling in order to achieve higher outputs. This way, this paper focuses on the effectiveness of forced air circulation methods by comparing the thermal performance of three specific concentrating bi-facial collector designs. This paper developed a computational model, using ANSYS Fluent intending to assess the thermal performance of a covered concentrating collector with bifacial Photovoltaic (PV) cells. These results have then been validated by outdoor measurements. Results show that even a simple natural ventilation mechanism such as removing the side gable can effectively reduce the receiver temperature, thus resulting in favourable cell operation conditions when compared to the case of an airtight collector. Therefore, compared with a standard model, a decrease of 13.5% on the cell operating temperature was reported when the side gables are removed. However, when forced ventilation is apllied a 22.8% reduction on temperature is found compared to the standard air-tight model. The validated CFD model has proven to be a useful and robust tool for the thermal analysis of solar concentrating systems.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136361794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-09-05DOI: 10.1177/09576509231200682
Belal Almasri, Sudhansu S Mishra, Taraprasad Mohapatra
This study proposes a heat transfer augmentation technique using a brazed helix tube (BHT) fabricated from a helical tube with precision brazing between coil turns in a novel multi-fluid heat exchanger (NMFHE) for simultaneous heating of water and air using solar energy. The thermo-hydraulic performance of the present NMFHE for residential heating of water (CW) and air (CA) using hot water (HW) is tested experimentally. Nusselt number and friction factor for fluid flow inside the NMFHE are calculated as the thermo-hydraulic measure relating to variations in flow rate, inlet temperature, and flow configuration. Optimal flow parameters for overall optimized performances that is, maximum heat transfer and minimum pressure drop in NMFHE are determined using the Taguchi Grey relational approach. NMFHE performs efficiently in the Counterflow (cold water reverse) flow configuration with HW flow rate of 100 LPH, CW flow rate of 200 LPH, and HW inlet temperature of 70°C. The CW flow rate has the greatest impact on both the Nusselt number and friction factor, with a contribution of 82.37% and 93.42%, respectively. A confirmation test has been conducted to validate the findings, revealing a significant performance improvement of 32.19% when using the Grey relational grade model.
{"title":"Thermo-hydraulic performance augmentation in residential heating applications using a novel multi-fluid heat exchanger with helical coil tube insertion","authors":"Belal Almasri, Sudhansu S Mishra, Taraprasad Mohapatra","doi":"10.1177/09576509231200682","DOIUrl":"https://doi.org/10.1177/09576509231200682","url":null,"abstract":"This study proposes a heat transfer augmentation technique using a brazed helix tube (BHT) fabricated from a helical tube with precision brazing between coil turns in a novel multi-fluid heat exchanger (NMFHE) for simultaneous heating of water and air using solar energy. The thermo-hydraulic performance of the present NMFHE for residential heating of water (CW) and air (CA) using hot water (HW) is tested experimentally. Nusselt number and friction factor for fluid flow inside the NMFHE are calculated as the thermo-hydraulic measure relating to variations in flow rate, inlet temperature, and flow configuration. Optimal flow parameters for overall optimized performances that is, maximum heat transfer and minimum pressure drop in NMFHE are determined using the Taguchi Grey relational approach. NMFHE performs efficiently in the Counterflow (cold water reverse) flow configuration with HW flow rate of 100 LPH, CW flow rate of 200 LPH, and HW inlet temperature of 70°C. The CW flow rate has the greatest impact on both the Nusselt number and friction factor, with a contribution of 82.37% and 93.42%, respectively. A confirmation test has been conducted to validate the findings, revealing a significant performance improvement of 32.19% when using the Grey relational grade model.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"48 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85290241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-09-01DOI: 10.1177/09576509231162169
Cleopatra Cuciumita, N. Qin, S. Shahpar
A novel optimisation process has been proposed in this paper to maximize the aerodynamic efficiency of a modern fan blade while satisfying the structural constraint imposed by the material limits. The method developed is based on the discrete adjoint for the aerodynamic efficiency sensitivity evaluation with the structural constraint provided by a response surface method for the structural stress. To facilitate a large number of sampling points required in the response surface generation, a fast, meshless method was used for the stress calculations. The method was applied to the optimisation of a practical fan blade, representative of modern, high-bypass-ratio turbofan jet engines. It is demonstrated that the fan blade efficiency can be improved by 0.6% while maintaining the stress below a prescribed value of 500 MPa assuming a titanium alloy material. It is shown that without the stress constraint, the efficiency benefit is larger, namely 0.9% but the maximum stress value increases considerably beyond the material’s acceptable criterion, to almost 1000 MPa. The method is built in a modular way and can be adapted to accommodate a range of different turbomachinery blade designs. Flutter analysis for the optimised fan blade has also been carried out due to its practical importance.
{"title":"Adjoint based aero-structural design optimisation of a transonic fan blade","authors":"Cleopatra Cuciumita, N. Qin, S. Shahpar","doi":"10.1177/09576509231162169","DOIUrl":"https://doi.org/10.1177/09576509231162169","url":null,"abstract":"A novel optimisation process has been proposed in this paper to maximize the aerodynamic efficiency of a modern fan blade while satisfying the structural constraint imposed by the material limits. The method developed is based on the discrete adjoint for the aerodynamic efficiency sensitivity evaluation with the structural constraint provided by a response surface method for the structural stress. To facilitate a large number of sampling points required in the response surface generation, a fast, meshless method was used for the stress calculations. The method was applied to the optimisation of a practical fan blade, representative of modern, high-bypass-ratio turbofan jet engines. It is demonstrated that the fan blade efficiency can be improved by 0.6% while maintaining the stress below a prescribed value of 500 MPa assuming a titanium alloy material. It is shown that without the stress constraint, the efficiency benefit is larger, namely 0.9% but the maximum stress value increases considerably beyond the material’s acceptable criterion, to almost 1000 MPa. The method is built in a modular way and can be adapted to accommodate a range of different turbomachinery blade designs. Flutter analysis for the optimised fan blade has also been carried out due to its practical importance.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"2 1","pages":"1141 - 1157"},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91141408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-08-25DOI: 10.1177/09576509231198906
Fan Yang, Sheng-jie Sun, Xiaoyu Jin, Sihai Li, Xudong Xu, Yan Jin
One of the often employed flow structures in vertical pumping stations is the siphon outlet pipe. It has a complicated geometric structure and internal flow field, which directly affects how effectively, safely, and steadily pumping stations operate. The entire flow conduit of the vertical axial flow pump device was adopted as the study object in order to elucidate the mechanism of the internal biased flow of the siphon outlet pipe caused by the axial flow pump under different flow conditions, and the three-dimensional unsteady flow field of the vertical axial flow pump device was numerically solved using the numerical simulation technique. Physical model tests were used to confirm the results of the numerical simulation. The findings demonstrate that there is a horizontal bias in the flow of the inlet surface and outlet surface of the elbow pipe of the siphon outlet pipe, and that when the flow rate rises, the degree of the horizontal bias in the flow gradually diminishes, and the ratio of biased flow gradually decreases. The flow in hump segment presents up-and-down flow, and when the flow rate increases, the ratios of biased flow first rises before falling. The major causes of the production of biased flow in the outlet pipe are residual velocity circulation at the guide vane's outlet, wall constraint at the elbow pipe, and flow inertia; Under various flow conditions, the morphologies of the vortex structures in the outlet pipe vary; the characteristics of the energy conversion of each part of the pump device are disclosed, with the inlet pipe having the lowest proportion of energy conversion. Under the optimal flow condition, the elbow-inlet pipe's proportion of energy conversion is only around 1.04%, and the proportions of the guide vane, 60° elbow pipe, and siphon outlet pipe's energy conversion are significant and fluctuate with time. The proportion of energy conversion in the elbow-inlet pipe and siphon outlet pipe steadily increases as flow rate rises, but the proportion in the guide vane and 60° elbow pipe drops initially before increasing.
{"title":"Numerical analysis of the internal biased flow mechanism of the siphon outlet pipe under the action of axial flow pump","authors":"Fan Yang, Sheng-jie Sun, Xiaoyu Jin, Sihai Li, Xudong Xu, Yan Jin","doi":"10.1177/09576509231198906","DOIUrl":"https://doi.org/10.1177/09576509231198906","url":null,"abstract":"One of the often employed flow structures in vertical pumping stations is the siphon outlet pipe. It has a complicated geometric structure and internal flow field, which directly affects how effectively, safely, and steadily pumping stations operate. The entire flow conduit of the vertical axial flow pump device was adopted as the study object in order to elucidate the mechanism of the internal biased flow of the siphon outlet pipe caused by the axial flow pump under different flow conditions, and the three-dimensional unsteady flow field of the vertical axial flow pump device was numerically solved using the numerical simulation technique. Physical model tests were used to confirm the results of the numerical simulation. The findings demonstrate that there is a horizontal bias in the flow of the inlet surface and outlet surface of the elbow pipe of the siphon outlet pipe, and that when the flow rate rises, the degree of the horizontal bias in the flow gradually diminishes, and the ratio of biased flow gradually decreases. The flow in hump segment presents up-and-down flow, and when the flow rate increases, the ratios of biased flow first rises before falling. The major causes of the production of biased flow in the outlet pipe are residual velocity circulation at the guide vane's outlet, wall constraint at the elbow pipe, and flow inertia; Under various flow conditions, the morphologies of the vortex structures in the outlet pipe vary; the characteristics of the energy conversion of each part of the pump device are disclosed, with the inlet pipe having the lowest proportion of energy conversion. Under the optimal flow condition, the elbow-inlet pipe's proportion of energy conversion is only around 1.04%, and the proportions of the guide vane, 60° elbow pipe, and siphon outlet pipe's energy conversion are significant and fluctuate with time. The proportion of energy conversion in the elbow-inlet pipe and siphon outlet pipe steadily increases as flow rate rises, but the proportion in the guide vane and 60° elbow pipe drops initially before increasing.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"04 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89714845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-08-23DOI: 10.1177/09576509231196210
Hongwei Li, Ruihan Gao, Changhe Du, Wenpeng Hong
In this paper, according to the actual size of gas turbine blade interior space, eight vortex cooling models with different cross-sectional shapes of coolant chambers are established. Rectangular, Circle, Trapezoidal up, Trapezoidal down, Ellipse up, Ellipse down, Sine up and Sine down are the eight coolant chamber shapes. Functions of variable coolant chamber structures on vortex cooling flow and heat exchange characteristics are numerically analyzed by verifying the Standard k- ω turbulence model and conducting grid independence analysis. Research results show that the heat exchange ability of Sine up coolant chamber is the best compared with the other coolant chambers. The cool air enters the vortex chamber at a faster speed and impacts on the target surface to form a high-pressure area and a low-temperature swirl. The more the cool air moves downstream, the greater the turbulent kinetic energy becomes, which is more conducive to the heat transfer. Therefore, Sine up coolant chambers have the highest thermal performance factor. Due to the low drag coefficient and high target surface average Nusselt number of Ellipse up, its thermal exchange performance is second only to that of Sine up. Circle coolant chamber will not bring favorable factors to engineering application because of the slowest flow speed and the worst heat exchange capacity. For Trapezoidal up and Trapezoidal down, the flow velocity, pressure distribution, turbulent kinetic energy intensity and heat transfer uniformity are almost the same as Rectangle coolant chamber. The models of Ellipse down and Sine down coolant chambers exhibit less turbulent kinetic energy strength to heat transfer and higher temperature in the vortex chamber, and it is not suggested for cooling system optimal design.
{"title":"Numerical investigation on vortex cooling flow and heat transfer characteristics for gas turbine blade with variable coolant chamber cross-sectional shapes","authors":"Hongwei Li, Ruihan Gao, Changhe Du, Wenpeng Hong","doi":"10.1177/09576509231196210","DOIUrl":"https://doi.org/10.1177/09576509231196210","url":null,"abstract":"In this paper, according to the actual size of gas turbine blade interior space, eight vortex cooling models with different cross-sectional shapes of coolant chambers are established. Rectangular, Circle, Trapezoidal up, Trapezoidal down, Ellipse up, Ellipse down, Sine up and Sine down are the eight coolant chamber shapes. Functions of variable coolant chamber structures on vortex cooling flow and heat exchange characteristics are numerically analyzed by verifying the Standard k- ω turbulence model and conducting grid independence analysis. Research results show that the heat exchange ability of Sine up coolant chamber is the best compared with the other coolant chambers. The cool air enters the vortex chamber at a faster speed and impacts on the target surface to form a high-pressure area and a low-temperature swirl. The more the cool air moves downstream, the greater the turbulent kinetic energy becomes, which is more conducive to the heat transfer. Therefore, Sine up coolant chambers have the highest thermal performance factor. Due to the low drag coefficient and high target surface average Nusselt number of Ellipse up, its thermal exchange performance is second only to that of Sine up. Circle coolant chamber will not bring favorable factors to engineering application because of the slowest flow speed and the worst heat exchange capacity. For Trapezoidal up and Trapezoidal down, the flow velocity, pressure distribution, turbulent kinetic energy intensity and heat transfer uniformity are almost the same as Rectangle coolant chamber. The models of Ellipse down and Sine down coolant chambers exhibit less turbulent kinetic energy strength to heat transfer and higher temperature in the vortex chamber, and it is not suggested for cooling system optimal design.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"24 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84561943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-08-21DOI: 10.1177/09576509231197035
Vinoth Kumar Jayakumar, Amarkarthik Arunachalam
The realm of sustainable energy systems has seen the salt gradient solar pond (SGSP) emerge as an eco-friendly solution for thermal energy storage. This research explores the use of an East-West (EW) reflector and coal cinder additive (CC) to enhance the energy efficiency of the inner zones of a salt gradient trapezoidal solar pond (SGTSP). In this work, SGTSP with EW and CC systems were designed, fabricated, and analyzed based on an energy point of view and compared with standard SGTSP systems. It also provides a shading area analysis based on the slant angle of the SGSP system, offering valuable insights into the system’s performance for low-grade heat source thermal applications. The study found that the EW reflector significantly increased the average solar intensity by 33.2%. The addition of coal cinder additive raised the average temperature of the lower convection zone by 24.1%. The SGTSP with EW reflector and coal cinder (SGTSP-EWR&CC) reached a maximum average temperature of 83.85°C, with a 42% higher energy efficiency in the lower convection zone compared to the conventional SGTSP (SGTSP-C). Further, the SGTSP’s potential for thermal energy storage and providing practical strategies for enhancing its energy efficiency is showcased.
{"title":"Enhancing energy efficiency in trapezoidal solar ponds: A synergistic approach utilizing east-west reflector and coal cinder – An energy analysis study","authors":"Vinoth Kumar Jayakumar, Amarkarthik Arunachalam","doi":"10.1177/09576509231197035","DOIUrl":"https://doi.org/10.1177/09576509231197035","url":null,"abstract":"The realm of sustainable energy systems has seen the salt gradient solar pond (SGSP) emerge as an eco-friendly solution for thermal energy storage. This research explores the use of an East-West (EW) reflector and coal cinder additive (CC) to enhance the energy efficiency of the inner zones of a salt gradient trapezoidal solar pond (SGTSP). In this work, SGTSP with EW and CC systems were designed, fabricated, and analyzed based on an energy point of view and compared with standard SGTSP systems. It also provides a shading area analysis based on the slant angle of the SGSP system, offering valuable insights into the system’s performance for low-grade heat source thermal applications. The study found that the EW reflector significantly increased the average solar intensity by 33.2%. The addition of coal cinder additive raised the average temperature of the lower convection zone by 24.1%. The SGTSP with EW reflector and coal cinder (SGTSP-EWR&CC) reached a maximum average temperature of 83.85°C, with a 42% higher energy efficiency in the lower convection zone compared to the conventional SGTSP (SGTSP-C). Further, the SGTSP’s potential for thermal energy storage and providing practical strategies for enhancing its energy efficiency is showcased.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"76 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90323288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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