首页期刊导航|Proceedings of the Institution of Mechanical Engineers, Part A. Journal of power and energy
期刊信息/Journal information
Proceedings of the Institution of Mechanical Engineers, Part A. Journal of power and energy
Published for the Institution of Mechanical Engineers by Mechanical Engineering Publications
Published for the Institution of Mechanical Engineers by Mechanical Engineering Publications
0957-6509
Proceedings of the Institution of Mechanical Engineers, Part A. Journal of power and energy/Journal Proceedings of the Institution of Mechanical Engineers, Part A. Journal of power and energy
查看更多>>摘要：Micro centrifugal pumps are commonly used in the medical field for transporting drugs or blood, etc. Due to the particularity of fluid media, irregular flow is often generated inside the pump resulting in over-high pressure pulsation and shear stress, which will eventually cause damage to the medium. In this paper, the internal flow field of a micro centrifugal pump was investigated through both visualization experiments and numerical simulations. When the main structure parameters of the impeller were selected as optimization variables, with pressure pulsation and shear stress as optimization objectives, a combination numerical simulation solution of BP neural network and genetic algorithm was employed to optimize the objectives respectively. The results indicate that the BP neural network model and genetic algorithm have high accuracy and can be used to predict the performance of micro centrifugal pumps. After optimization, the pressure pulsation strength coefficient of the monitoring point near the volute tongue is reduced by 40%. The internal flow of the micro centrifugal pump becomes more stable. The maximum shear stress of the impeller is declined by 42% and 28% in the volute. The research is of great significance to improve the stability and efficiency of micro centrifugal pumps.
查看更多>>摘要：This study explores the interrelationship between pump performance, system efficiency, and noise/vibration levels by analyzing the influence of pump frequency and outlet pressure. System efficiency predictions were conducted utilizing both the Response Surface Method (RSM) and advanced machine learning algorithms, including Artificial Neural Networks (ANN), Support Vector Machines (SVM), and XGBoost. The comparative analysis revealed that ANN provided the highest prediction accuracy with an R~2 value of 0.946, Root Mean Square Error (RMSE) of 1.2% and Mean Absolute Percentage Error (MAPE) of 2.32%. However, when predicting system efficiency using external data inputs, RSM outperformed other models, achieving an R~2 value of 0.96 and a mean error rate of 3.84%. Optimization via RSM was performed for target flow rates of 35, 40, and 45 m~3 h~(-1), with the optimal flow rate determined at 35 m~3 h~(-1), corresponding to a system efficiency of 42%. To validate these optimization results, experimental tests were conducted, revealing a flow rate of 35.4 m~3 h~(-1) and system efficiency of 42.95%, with error margins of 1.12% and 2.21%, respectively. The study demonstrates that RSM is a robust and effective tool for optimizing pump system performance, offering practical applications in improving energy efficiency and operational stability in pumping facilities.
查看更多>>摘要：As a typical fluid machine, the centrifugal pump system experiences impeller angular misalignment resulting from manufacturing and assembly errors. A new computational fluid dynamics (CFD) simulation model is developed to investigate the effect of impeller angle misalignment on the internal flow characteristics of a centrifugal pump. The transient flow is described by applying the shear stress transport (SST) k-ω turbulence model. The results reveal that an increase in the impeller angular misalignment exacerbates the flow inhomogeneity and instability. This failure can reduce the head and efficiency; it can increase the flow turbulence in the pump. Furthermore, the angular misalignment leads to an elevated circumferential pressure gradient at the inlet and outlet of the impeller. It amplifies the peaks of axial frequencies and their harmonics, which can disrupt the uniformity of the radial force distribution. This study provides some valuable numerical references for the analysis of angular misalignment failures and vibration control. It can also offer a basis for the optimal design and vibration mitigation of centrifugal pump impellers.
查看更多>>摘要：Applied mathematical modeling of the various energy resources has contributed widely in their design and operation improvements. Among renewable energy sources, wind energy systems have gained a significant attention for their rapid and continuous growth, which resulted from their cost effectiveness and clean power generation. However, research effort on the industry and university levels is still needed to enhance the characteristics of existing wind turbines and allow larger amounts of their share. This thesis presents an accurate model of a wind turbine (TWT-1.65) system for time-based dynamic simulations. The parameters of the power coefficient have been identified, calibrated and verified using different meta-heuristic optimization techniques, which are the Wild Horse Optimizer (WHO), Whale Optimizer (WO), and Genetic Algorithm (GA) to enhance the model accuracy over the previously related studies. The new version of the parameters has resulted in a higher accuracy while being practically meaningful, with the best achieved MSE of 0.006. The system model has been then integrated with two predictive controllers which are the linear Model Predictive Control (MPC) and Neural Network Predictive Control (NNPC) to regulate the pitch angle trends for the target of maximum energy harvesting. With proper selection of the controllers' parameters, off-line simulation studies have shown improved production trends of the power output with constrained and safe trajectory of the pitch angle, which can be translated to be an improve in the total average harvested power of 34% and 44.5% over the complete time window of 5760 min using NNPC and Linear MPC respectively.
查看更多>>摘要：Ice accretion on the blade surface, particularly the glaze ice with protruded horns, causes a severe decrease in the wind power utilization. The characteristics research on the airfoil under glaze ice conditions is the basis of exploring the anti-icing method in view of the important role of an airfoil in the aerodynamic shape of the blade. The protruded horn shape of glaze ice complicates the meshing process of airfoils and increases the number of grids, whereas more grid cells make the amount of aerodynamic computation huge. In the present study, a novel neural network method is developed for the prediction of the aerodynamic performance of wind turbine airfoils with glaze ice. The biases of nodes, connection weights between nodes, and parameters of link switches are chosen as the design variables. The social learning is adopted to modify the potential well center update mode of non-optimal particles, and the Levy flight is combined with greedy algorithm to identify the position of optimal particles for Quantum Particle Swarm Optimization (QPSO) algorithm. The testing error is introduced to interfere with the selection of global optimal particle, and the optimizer, based on the SLLQPSO (with SLLQPSO denoting improved QPSO) algorithm combined with Binary Particle Swarm Optimization (BPSO) algorithm, seeks the solutions minimizing the training error of neural network. A new neural network, namely SLLQPSO-BPNN, is established after being trained by Back Propagation (BP) algorithm, and predicts the lift and drag coefficients of S809 and NACA64618 airfoils with glaze ice. Significant performance improvements are achieved for QPSO algorithm and neural network, confirming that a novel neural network method with high accuracy is provided for the aerodynamic performance analysis of wind turbine airfoils.
A. E. HussinM. M. KamalW. A. AboelsoudA. M. Hamed...
680-698页
查看更多>>摘要：The rapid development of freshwater resources from renewable energy sources plays an important role in satisfying the modern life requirements. When it comes to the solar energy, one of the major issues is how to improve the performance and productivity of solar stills. In this respect, more attention is paid to the solar pump oscillating flow impact on the performance and how turbulence affects the freshwater productivity. This work investigates the impact of flow oscillation frequency, non-circular jets and porosity on the solar still productivity and expresses the functional form which relates the productivity, Prandtl number; Reynolds number and the solar intensity. An innovative design comprising a pyramid stepped solar still and a solar pump is combined with solar concentrators. It was found that the flow oscillation caused water depth fluctuation thus minimizing the thermal inertia, while metallic porous structures enhanced the evaporation rates. The water jet inertia affected the turbulence largest scale. Employing a flow oscillation frequency of 1.4 Hz increased the turbulent kinetic energy to 12.5 m~2/s~2. The freshwater productivity reached 7.2 L/m~2.day at an optimum porosity of 0.6. A squared water jet was found to be superior whereby the productivity became 8.4 L/m~2 day. A copper helical absorber with a pitch/coil diameter ratio of 0.5 and a black paint maximized the productivity to 10.8 L/m~2 day.
查看更多>>摘要：Greater heat transfer area is provided since the special porous media frame structure for metal foam. However, it also increases fluid flow resistance, which is not conducive to fluid flow. In this study, the Sarracenia trichome bionic channel structure is innovatively developed to reduce the flow resistance. First, six different types of bionic hierarchical microchannels are modeled using metal foam concerning the high and low rib structure of Sarracenia trichomes. The gas-liquid two-phase flow process is simulated numerically in each microchannel by using R141b refrigerant. Then, the synergy coefficients are compared between the bubble number and heat transfer coefficient in different microchannels. Finally, the velocity field and streamline distribution of the microchannels are studied, and the flow resistances are analyzed. Results show that the bubble number and heat transfer coefficient in the high and low rib microchannels follow the same synergistic trend as the other microchannels. Furthermore, two continuous but different fluid transport modes exist in the hierarchical microchannels with high and low rib structures. The bionic structure transport modes improve the water transport performance and reduce the flow pressure drop.
查看更多>>摘要：The present study investigates a novel battery thermal management system employing air cooling with a stair-step configuration. Experimental research focused on a battery pack with nine lithium-ion cells, complemented by Computational Fluid Dynamics (CFD) simulations using an Ansys-Fluent battery module. Initially, the battery pack reached a temperature of 80℃ under load, which was reduced to 60℃ with air cooling. The introduction of an additional cooling fan at the top further lowered cell temperatures to 49℃. The incorporation of the stair-step design and secondary fan increased cooling efficiency from 10% to 14.2%. Numerical simulations identified hot-spots and convection currents within the battery module. Overall, the most desired design is a combination of the stair step configuration with an additional fan. These findings hold promise for enhancing the thermal management of lithium-ion batteries and optimizing their overall performance and safety.
查看更多>>摘要：Aero-engines are designed to operate at extremely high temperatures to achieve the highest possible efficiency and specific power during operation. Such extreme temperatures place extraordinarily high thermal loads on engine components, the melting points of which can be easily exceeded; thus, significant harm can be caused to the engines if efficient cooling measures are not provided. This paper reviews the global research progress regarding the flow and heat transfer characteristics of turbine rotor-blade end-walls, comprehensively analyzes typical research results for air-film cooling in the end-wall region along with its influencing factors, and summarizes simulation and experimental methods used to study end-wall flow and cooling characteristics. Finally, it emphasizes future research directions, which include end-wall structural modifications, improved cooling technologies, better cooling-efficiency measurement methods, and more robust composite materials.
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