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.

Influence of Stator Blade Geometry on Torque Converter Cavitation

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Cheng Liu ◽  
Wei Wei ◽  
Qingdong Yan ◽  
Brian K. Weaver ◽  
Houston G. Wood
Keyword(s):  
High Speed ◽  
Torque Converter ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Speed Ratio ◽  
Capacity Loss ◽  
Wide Range ◽  
Stator Blade ◽  
Torque Converters ◽  
Blade Geometry

Cavitation in torque converters may cause degradation in hydrodynamic performance, severe noise, or even blade damage. Researches have highlighted that the stator is most susceptible to the occurrence of cavitation due to the combination of high flow velocities and high incidence angles. The objective of this study is to therefore investigate the effects of cavitation on hydrodynamic performance as well as the influence of stator blade geometry on cavitation. A steady-state homogeneous computational fluid dynamics (CFD) model was developed and validated against test data. It was found that cavitation brought severe capacity constant degradation under low-speed ratio (SR) operating conditions and vanished in high-speed ratio operating conditions. A design of experiments (DOE) study was performed to investigate the influence of stator design variables on cavitation over various operating conditions, and it was found that stator blade geometry had a significant effect on cavitation behavior. The results show that stator blade count and leaning angle are important variables in terms of capacity constant loss, torque ratio (TR) variance, and duration of cavitation. Large leaning angles are recommended due to their ability to increase the cavitation number in torque converters over a wide range of SRs, leading to less stall capacity loss as well as a shorter duration of cavitation. A reduced stator blade count is also suggested due to a reduced TR loss and capacity loss at stall.

scholarly journals Laser Velocimeter Measurements in the Stator of an Automotive Torque Converter

2000 ◽  
Vol 6 (6) ◽  
pp. 417-431 ◽  
Author(s):  
Steven B. Ainley ◽  
Ronald D. Flack
Keyword(s):  
Secondary Flow ◽  
Mass Flow ◽  
Torque Converter ◽  
Speed Ratio ◽  
Pressure Side ◽  
Suction Surface ◽  
General Direction ◽  
Flow Rates ◽  
Pressure Surface ◽  
Mass Flow Rates

The flow field in the stator of a clear torque converter was studied using laser velocimetry. Five planes in the stator were studied at a speed ratio of 0.800 and three planes were studied at a speed ratio of 0.065. Data complements previously available pump and turbine data. Flow in the stator inlet plane is highly non-uniform due to the complicated flow exiting the turbine. At the 0.800 speed ratio, separation regions are located in the 1/4 and mid-planes in the corepressure corner region. In the 3/4 and exit planes, separation regions are located in the shellsuction corner. In the inlet plane a region of high velocities is located along the shell near the pressure side for a speed ratio of 0.800. The high velocity region migrated to the shell-suction corner and suction side in the 1/4 and mid-planes. The overall velocity field for the speed ratio of 0.065 changes significantly from the inlet plane to the mid-plane. The velocity magnitude generally decreases from the suction to the pressure side of the inlet plane and the general direction of the tangential velocity is from pressure-to-suction surface. At the speed ratio of 0.065 a strong secondary flow in the inlet from suction surface to pressure surface was seen. However, at the high speed ratio a moderate secondary flow in the inlet from pressure surface to suction surface was observed. Mass flow rates at the different planes are within the experimental uncertainty and also within the uncertainty of pump and turbine mass flow rates. The flow in the stator inlet plane are significantly influenced by the turbine relative blade position. The turbine influence on the mid-plane data is significantly less than on the inlet plane data. The influence of the pump blade position on the stator exit plane is small.

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.

Performance improvement and flow field investigation in hydraulic torque converter based on a new design of segmented blades

2020 ◽  
Vol 234 (8) ◽  
pp. 2162-2175
Author(s):  
Chunbao Liu ◽  
Konghua Yang ◽  
Jing Li ◽  
Zhixuan Xu ◽  
Tongjian Wang
Keyword(s):  
Turbine Blade ◽  
Fuel Economy ◽  
Transient Flow ◽  
Torque Converter ◽  
Transmission Efficiency ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Start Up ◽  
Computational Fluid Dynamics Analysis ◽  
Hydraulic Torque Converter

Hydraulic torque converter is of lower efficiency in the powertrain, particularly at low speed ratio, which is crucial for vehicles due to its ability of torque multiplication. Therefore, torque converters should be taken into account with both higher start-up acceleration and transmission efficiency. Inspired by the fact that the multi-airfoils of the aircraft can improve the lift, a new design of segmented turbine blade in torque converter is presented to improve the transmission efficiency and start-up acceleration. To ensure reproducibility and popularization, the camber line and shape of blades are extracted to obtain the expression in the Cartesian coordinate system. A scale-resolving simulation setting, large eddy simulation with kinetic energy transport, and refined hexahedron meshes, which were verified by our studies, are applied to simulate the three-dimensional transient flow numerically. According to the results of computational fluid dynamics analysis, the new design eliminated the ultra-high vorticity of the near-wall boundary layer to reduce the flow loss, which further improves fuel economy. The pressure difference in the segmented turbine blade is significantly higher than that of the original model, causing the improvement of powertrain performance. As a result, the torque ratio and nominal torque increase by 6.7% and 7.7%, respectively, at stalling speed ratio; meanwhile, the maximum efficiency increases by 1.1%. This research, using a new design of segmented blades, has many advantages, such as high starting torque ratio, large adjusting range, and greater fuel economy, and shows great potential to apply in the manufacturing process.

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.

Performance Analysis of Automotive Torque Converter Elements

1999 ◽  
Vol 121 (2) ◽  
pp. 266-275 ◽  
Author(s):  
E. Ejiri ◽  
M. Kubo
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Leading Edge ◽  
Small Variation ◽  
Torque Converter ◽  
Hydrodynamic Performance ◽  
Speed Ratio ◽  
Loss Coefficients ◽  
Edge Separation ◽  
Ratio Range

The hydrodynamic performance of a three-element automotive torque converter is analyzed by measuring flow between the elements with five-hole Pitot tubes. The performance of each element, including head, head loss, and efficiency, is defined and evaluated. The results show that the pump is the major source of loss in the speed ratio range where vehicles are most frequently operated in everyday driving. The loss coefficients for the three elements are also evaluated using a one-dimensional flow model. The friction loss coefficient of the turbine shows small variation over the entire tested speed ratio range, whereas the coefficients of the pump and stator vary considerably according to the operating speed ratio. The cause of loss in the pump and stator is investigated by flow visualization and three-dimensional numerical flow analysis. A low kinetic energy region in the pump and leading edge separation in the stator are clearly visualized or computed.

Effect of Rotational Speed on the Average Flow Field at the Pump/Turbine Interface of an Automotive Torque Converter

2001 ◽  
Author(s):  
M. Hotho ◽  
M. R. Gruber ◽  
R. D. Flack ◽  
G. T. Gillies
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Leading Edge ◽  
Torque Converter ◽  
Flow Fields ◽  
Speed Ratio ◽  
Exit Plane ◽  
Pump Turbine ◽  
Plane Flow ◽  
The Core

Abstract The internal flow fields of a pump/turbine interface in a torque converter were examined using laser velocimetry. The torque converter was operated at three different turbine/pump rotational speed ratios: 0.065 (near stall), 0.600, and 0.800 (near coupling point) and for each speed ratio three different pump and turbine speeds were used. Most importantly, the dimensional rotational speed had minimal effects on the flow fields — flow characteristics were Reynolds number independent. At the pump exit plane the flow is non-uniform in the blade-to-blade direction at all speed ratios and speeds. Velocities were fairly uniform in the core-to-shell direction. Through flow velocity non-uniformity became more pronounced as the speed ratio increased. The pump exit plane slip factors are near unity. At high speed ratios the flow in the turbine inlet plane flow is non-uniform in the blade-to-blade direction. Also at high speed ratios, velocities are fairly uniform in the core-to-shell direction but high velocities move near the shell at lower speed ratios. The turbine leading edge incidence angles were found to depend strongly on the speed ratio, ranging from positive to negative.

Experimental Investigation of the Flow Field in an Automotive Torque Converter Stator

1999 ◽  
Vol 121 (4) ◽  
pp. 788-797 ◽  
Author(s):  
Y. Dong ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Flow Separation ◽  
Free Stream ◽  
Torque Converter ◽  
Transitional Flow ◽  
Speed Ratio ◽  
Corner Flow ◽  
Stator Blade ◽  
Hot Film

The flow field at the exit of a torque converter stator exit was measured using a miniature conventional five-hole probe. The data at speed ratio 0.8, 0.6, and 0.065 are presented. At the speed ratio 0.6, the stator exit flow is dominated by a large free-stream, accompanied by the blade wake and corner flow separation. A strong secondary flow is observed at the stator exit, the flow is overturned near the core and underturned near the shell. The secondary flow at inlet produces large radial transport of mass flow inside the stator passage. The shell-suction corner flow separation has a large blockage effect, resulting in losses. To determine the nature of the transitional flow in the stator passage, the surface hot-film sensors were mounted on the stator blade surface. The data confirm that the stator flow field is turbulent.

scholarly journals Surface Quality Improvement by Using a Novel Driving System Design in Single-Side Planetary Abrasive Lapping

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1691 ◽  
Author(s):  
Zhenzhen Chen ◽  
Donghui Wen ◽  
Jianfei Lu ◽  
Jie Yang ◽  
Huan Qi
Keyword(s):  
System Design ◽  
Surface Quality ◽  
Material Removal ◽  
Rotation Speed ◽  
Target Surface ◽  
Speed Ratio ◽  
The Novel ◽  
Particle Trajectories ◽  
Driving System ◽  
Single Side

For the traditional single-side planetary abrasive lapping process particle trajectories passing over the target surface are found to be periodically superposed due to the rational rotation speed ratio of the lapping plate to workpiece that could affect the material removal uniformity and hence its surface quality. This paper reports on a novel driving system design with combination of the tapered roller and contact roller to realize the irrational rotation speed ratio of the lapping plate to workpiece in the single-side planetary abrasive lapping process for the improvement of surface quality. Both of the numerical and experimental investigations have been conducted to evaluate the abrasive lapping performance of the novel driving system. It has been found from the numerical simulation that particle trajectories would theoretically cover the whole target surface if the lapping time is long enough due to their non-periodic characteristics, which can guarantee the uniformity of material removal from the surface of workpiece with relatively high surface quality. The encouraging experimental results underline the potential of the novel driving system design in the application of the single-side planetary abrasive lapping for the improvement of the surface quality in terms of surface roughness and material removal uniformity.

scholarly journals Pressure Analysis in the Draft Tube of a Pump-Turbine under Steady and Transient Conditions

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4732
Author(s):  
Jing Yang ◽  
Yue Lv ◽  
Dianhai Liu ◽  
Zhengwei Wang
Keyword(s):  
Steady State ◽  
Pressure Pulsation ◽  
Transient Flow ◽  
Draft Tube ◽  
Simulation Method ◽  
Wall Pressure ◽  
Pump Turbine ◽  
Steady State Condition ◽  
Transient Conditions ◽  
Pumped Storage

Pumped-storage power stations play a regulatory role in the power grid through frequent transition processes. The pressure pulsation in the draft tube of the pump-turbine under transient processes is important for safe operation, which is more intense than that in the steady-state condition. However, there is no effective method to obtain the exact pressure in the draft tube in the transient flow field. In this paper, the pressure in the draft tube of a pump-turbine under steady-state and transient conditions are studied by means of CFD. The reliability of the simulation method is verified by comparing the real pressure pulsation data with the test results. Due to the distribution of the pressure pulsation in the draft tube being complex and uneven, the location of the pressure monitoring points directly affects the accurate judgement of cavitation. Eight monitoring surfaces were set in the straight cone of the draft tube and nine monitoring points were set on each monitoring surface to analyze the pressure differences on the wall and inside the center of the draft tube. The relationships between the pressure pulsation value inside the center of the draft tube and on the wall are studied. The “critical” wall pressure pulsation value when cavitation occurs is obtained. This study provides references for judging cavitation occurrences by using the wall pressure pulsation value in practical engineering.

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