scholarly journals Effect of internal leakage on torque converter characteristics

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095996
Author(s):  
Xiong Pan ◽  
Chen Xinyuan ◽  
Sun Hongjun ◽  
Zhong Jiping ◽  
Zhen Chenping
Keyword(s):  
Energy Loss ◽  
Pressure Pulsation ◽  
Internal Flow ◽  
Torque Converter ◽  
Main Flow ◽  
Speed Ratio ◽  
Leakage Flow ◽  
Flow State ◽  
Simulation Accuracy ◽  
Leakage Area

To understand the effect of internal leakage on the torque field and characteristics of a torque converter (TC), a transient analysis was performed on the internal flow of a TC and the pressure pulsation characteristics of monitoring points in the convection channel. It was found that dividing the leakage area of the TC into a separate watershed improved simulation accuracy by 4%. When there was a leakage area, there were distinct collision, mixing, and assimilation stages between the leakage flow and the main flow. These phenomena caused energy loss that was highest at low speed ratios. However, the leakage flow always accounted for 12% of the main flow regardless of the speed ratio. At the same time, the leakage flow had a larger influence on pressure pulsation inside the TC and especially the low frequency band was more substantial. This shows that the leakage area has a large influence on the TC performance, energy loss, and flow state. Analysis of the leakage area showed that reducing the leakage area helps to improve powertrain performance and fuel economy.

Influence of Pump Rotation Speed on Hydrodynamic Performance and Stator Blade Surface Pressure Pulsation in Torque Converter

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Boshen Liu ◽  
Lu Tan ◽  
Jin Li
Keyword(s):  
Pressure Pulsation ◽  
Rotation Speed ◽  
Torque Converter ◽  
Transmission Efficiency ◽  
Hydrodynamic Performance ◽  
Speed Ratio ◽  
Pump Turbine ◽  
Pressure Surface ◽  
Efficiency Increase ◽  
Stator Blade

Abstract An experimental investigation was performed to characterize the influence of pump rotation speed on the hydrodynamic performance and the associated unsteady pressure on the stator blade pressure-surface in a torque converter. High-resolution miniature transducers were used to obtain the signature of the pressure pulsation at specific surface locations. Results show that the increase of the pump rotation speed can enhance the torque capacity of the stator, leading to a higher torque ratio in the low speed ratio range and an improvement of the highest transmission efficiency. The efficiency increase rate starts to reduce at approximately SR = 0.4, corresponding to where the stator capacity reaches the maximum and exhibits a uniform distribution of the pressure pulsation intensity. The spectral decomposition of the pulsating pressure reveals the existence of two dominating frequencies, which corresponds to the upstream pump turbine interaction and the downstream pump blade passing. Higher pump speeds enhance the pump turbine interaction and results in a more regular pressure pulsation, improving the hydrodynamic performance of the torque converter.

scholarly journals Analysis of Flow Within Pump Impeller of Torque Converter

1996 ◽  
Author(s):  
Hoshio Tsujita ◽  
Shimpei Mizuki ◽  
Eiji Ejiri
Keyword(s):  
Coordinate System ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Torque Converter ◽  
Flow Patterns ◽  
Speed Ratio ◽  
Meridional Plane ◽  
Pump Impeller ◽  
Simple Method

It is difficult to measure flow patterns within rotating elements of a torque converter due to the complicated construction. Therefore, the numerical calculation is considered to be an effective tool to know the internal flow. Three-dimensional incompressible turbulent flow within a pump impeller of an automotive torque converter was analyzed numerically at three different speed ratios, 0.02, 0.4 and 0.8 under the same inlet boundary condition. The speed ratio was defined as the ratio of rotating speed of the turbine impeller to that of the pump. The governing equations using the k-ε model in the physical component tensor form were solved with a boundary-fitted coordinate system fixed on a rotating impeller. The solution algorithm was the SIMPLE method applied to the curvilinear coordinate system. The computed results were compared with those obtained experimentally by an oil film flow visualization technique for the pressure, suction, core and shell surfaces. Moreover, the results at three different speed ratios were examined in detail in order to clarify the behavior of secondary flow patterns. The computed results showed good agreement with the experimental results and clarified the behavior of the complicated flow patterns. The secondary flow patterns were strongly influenced by the correlation between the intensities of the Corinlis force (COF) and the centrifugal force due to the passage curvature in the meridional plane (CMF).

Analysis of Energy Loss Mechanism at the Speed Ratio of Design Operating Condition in Hydrodynamic Torque Converters

2016 ◽  
Author(s):  
Qingdong Yan ◽  
Mingxing Huang ◽  
Wei Wei
Keyword(s):  
Flow Field ◽  
Energy Loss ◽  
Vortex Structure ◽  
Internal Flow ◽  
Good Method ◽  
Transmission Efficiency ◽  
Speed Ratio ◽  
Loss Mechanism ◽  
Operating Condition ◽  
Torque Converters

Low transmission efficiency of hydrodynamic torque converters limits their wider application, so it is necessary to observe the microstructures of internal flow in depth and to analyze the mechanism of energy loss for reducing the energy loss in flow field. Computational Fluid Dynamics (CFD) is a common way to model and simulate the flow field and Proper Orthogonal Decomposition (POD) is also a good method to do some simplified calculation. Combined CFD and POD, internal flow field in a hydrodynamic torque converter was analyzed to study the relationships among energy percentage of the first mode, vortex structure and the mechanism of energy loss on design operating condition (speed ratio of 0.7). Compared with the energy percentage amount of the first mode, the phenomenon was found that the vortex structure of the internal flow field became clearer with larger percentage amount. Therefore, the existence of regular vortex structure is the major reason for energy loss inside hydrodynamic torque converters. The position of vortex core went hand in hand with internal structures not only with the existence of low pressure area, but also the different locations with various features, which should be adopted to improve the performance in hydrodynamic torque converters.

Flow Pattern Evolution and Energy Decomposition of Flows at Different Operating Conditions in a Hydrodynamic Torque Converter

2016 ◽  
Author(s):  
Wei Wei ◽  
Mingxing Huang ◽  
Yu Li ◽  
Qingdong Yan
Keyword(s):  
Vortex Structure ◽  
Velocity Vector ◽  
Power Transmission ◽  
Flow Behavior ◽  
Internal Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Energy Decomposition ◽  
Complex Flow

Power loss and flow blockage in turbomachinery such as hydrodynamic torque converter are usually caused by jet flow, second flow and flow separation. In this paper, the velocity vector and the pressure distribution of the internal flow field in hydrodynamic torque converter were reduced by the method of the Proper Orthogonal Decomposition (POD) to find the main flow structures and the energy decomposition in the passages of pump, turbine and stator. In order to find their evolutionary processes and energy decompositions, oil flow visualizations were conducted at different speed ratios from 0 to 0.8, including stall condition and design operating condition. The results showed that the first few modes containing the majority of energy could provide enough accuracy to predict flow behavior and flow structure in flow passages. Especially when the energy percentage of the first mode was majority, its vortex structures could be recognized easily. But the flow patterns of other modes were different from each other and they made the flow more turbulent and complex, which increases the energy loss in the process of power transmission. Besides that, the change of pressure gradient had a direct influence to velocity vector. The results also indicated that the observed fluid pattern of vortex structure became extensive while the influence of secondary flow decreased in the flow passage of pump with the increase of speed ratio. But the situation is just reversed in turbine, that is, the vortex disappeared gradually and the irregular turbulent flow appeared as the increase of speed ratio. In stator, the vortex structure emerged gradually when the speed ratio increased. So the method of snapshots is a very useful way to analyze the complex flow flied in depth and to predict the trend of development.

Numerical Simulation of Torque Converter With Different Pump Blade Camber

2019 ◽  
Author(s):  
Zhifang Ke ◽  
Cheng Liu ◽  
Wei Wei ◽  
Qingdong Yan ◽  
Xianglu Meng
Keyword(s):  
Internal Flow ◽  
Torque Converter ◽  
Flow Fields ◽  
Hydrodynamic Performance ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Main Function ◽  
Flow Mechanism ◽  
Entrance Angle ◽  
The Difference

Abstract The main function of the torque converter pump is to transfer mechanical power into fluid dynamic energy. It has been proved that the pump blade shape, especially pump blade camber peak, is crucial to torque converter hydrodynamic performance. However, it remains unclear how this parameter affects internal flow characteristics, and how it leads to the difference in performance. Thus, the relationship between the pump blade camber and the performance of torque converter and the flow mechanism were explored in this study. Torque converters with different pump blade camber were tested. Meanwhile, the corresponding numerical models were also established and their internal flow fields were investigated through steady-state simulations. The influence of the pump blade camber on the hydrodynamic performance was studied using both numerical and experimental methods, and the flow mechanism was also revealed and elaborated by exploring the numerical flow fields. The results from both experiments and simulations showed that larger pump blade camber peak led to higher pump capacity, higher maximum efficiency and lower stall torque ratio. The flow field simulation revealed that larger pump camber peak would lead to higher total pressure in pump channel. And the pressure distribution between the suction and pressure surface showed a similar pattern; however, their difference, especially near the leading and tailing edge, depends on the camber peak. Besides, higher camber peak blade absorbed more power, also induced more complex vortex, but there always existed the most efficient speed ratio when pump efficiency can reach to peak, at this moment, the difference between angle of attack and entrance angle reach the zero, which can be used to guide the design of pump blade.

Study on Flow Induced Vibration Mechanism of Internal Flow Field in Hydraulic Torque Converter

2019 ◽  
Author(s):  
Zhifang Ke ◽  
Cheng Liu ◽  
Qingdong Yan ◽  
Wei Wei ◽  
Zemin Song
Keyword(s):  
Flow Field ◽  
Internal Flow ◽  
Simulation Method ◽  
Torque Converter ◽  
Flow Channel ◽  
Speed Ratio ◽  
Suction Surface ◽  
Flow Induced Vibration ◽  
Flow Fluctuation ◽  
Wheel Torque

Abstract By means of pseudo lumped-blade simulation method (PLSM), the blade torque vibration in the torque converter under different speed ratios is extracted and analyzed. The result indicates that the wheel torque pulsation is induced by flow fluctuation, while the mechanism of this flow fluctuation lies in the continuous switch of the blade position of pump and turbine related to the stator. There are mainly two states for stator flow channel: “pass” and “block”. In the “pass” state, the upstream flow channel is aligned to the downstream inlet. Besides, due to the influence of the wake transmitted from the upstream wheel and the vortex vortex arisen from the suction surface of the blade, the blade torque would be relatively larger in the “pass” state. The successively switch between the two states leads to the fluctuations of the blade torque, so as to its wheel torque, which which is the sum of all blade torques. However, due to the inconsistent relative position of the different wheel blades, the “offset” effect leads to the fact that the fluctuation of wheel torque is much smaller than that of the blade torque. In addition, by applying FFT transformation on the transient torque data, the frequency distribution of the blade surface pressure is obtained. It was found that rotation frequencies and interaction frequencies with both upstream and downstream components are significant, and the dominant frequency is always the interaction frequency at different speed ratio, which reveals that the successively switch of the turbine blade position related to stator are the main cause of its flow induced vibration, and this vibration can be transmitted downstream the flow channel, and affect the flow field of other components downstream.

TORQUE CONVERTER INTERNAL FLOW: VISUALIZATION AND IMAGE PROCESSING

2017 ◽  
Vol 24 (1-4) ◽  
pp. 209-222
Author(s):  
Fujio Yamamoto ◽  
Ari-isa Wada ◽  
Manabu Iguchi ◽  
Masa-aki Ishikawa
Keyword(s):  
Image Processing ◽  
Flow Visualization ◽  
Internal Flow ◽  
Torque Converter

scholarly journals Influence of Seal Cavity Leakage Flow on Compressor Performance Investigated with a Circumferentially Averaged Method

2021 ◽  
Vol 11 (2) ◽  
pp. 780
Author(s):  
Dong Liang ◽  
Xingmin Gui ◽  
Donghai Jin
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Interaction Mechanism ◽  
Main Flow ◽  
Leakage Flow ◽  
Destructive Effect ◽  
Through Flow ◽  
Compressor Performance ◽  
Overall Performance ◽  
Flow Blockage

In order to investigate the effect of seal cavity leakage flow on a compressor’s performance and the interaction mechanism between the leakage flow and the main flow, a one-stage compressor with a cavity under the shrouded stator was numerically simulated using an inhouse circumferentially averaged through flow program. The leakage flow from the shrouded stator cavity was calculated simultaneously with main flow in an integrated manner. The results indicate that the seal cavity leakage flow has a significant impact on the overall performance of the compressor. For a leakage of 0.2% of incoming flow, the decrease in the total pressure ratio was 2% and the reduction of efficiency was 1.9 points. Spanwise distribution of the flow field variables of the shrouded stator shows that the leakage flow leads to an increased flow blockage near the hub, resulting in drop of stator performance, as well as a certain destructive effect on the flow field of the main passage.

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