scholarly journals 3D Cavitation Shedding Dynamics: Cavitation Flow-Fluid Vortex Formation Interaction in a Hydrodynamic Torque Converter

2021 ◽  
Vol 11 (6) ◽  
pp. 2798
Author(s):  
Zilin Ran ◽  
Wenxing Ma ◽  
Chunbao Liu
Keyword(s):  
Local Density ◽  
Vortex Formation ◽  
Three Dimensional ◽  
Torque Converter ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Cavitation Flow ◽  
Flow Induced Vibration ◽  
Alternative Analysis ◽  
Vortex Interactions

Recent experiments have shown interactions between the cavitation and fluid vortex formation in a hydrodynamic torque converter. This study aimed to clarify the unsteady cavitation trigger mechanism and flow-induced vibration caused by turbulence–cavitation interactions. The mass transfer cavitation model and modified Reynolds-averaged Navier–Stokes k–ω model were used with a local density correction for turbulent eddy viscosity to investigate the cavitation structure in a hydrodynamic torque converter under various operating conditions. The model results were then validated against test data. The multi-block structured gridding technique was used to develop an orthogonally structured grid of a three-dimensional full-flow passage as an alternative analysis method for the cavitation flow. The results indicated that the re-entrant jet is the main cause of the shedding cavitation and breaking O-type cavitation. The re-entrant jet is driven by the reverse pressure gradient to move upstream towards the stator nose, and it lifts and splits the attached cavitation, which periodically induces shedding cavitation. When the cavitation was considered, the prediction error of the capacity constant was reduced from 13.23% to <5%. This work provides an insight into the cavitation–vortex interactions in a hydrodynamic torque converter, which can be used to improve the prediction accuracy of the hydrodynamic performance.

Numerical study of the impact of water injection holes arrangement on cavitation flow control

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987774 ◽  
Author(s):  
Wei Wang ◽  
Qingdian Zhang ◽  
Tao Tang ◽  
Shengpeng Lu ◽  
Qi Yi ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Water Injection ◽  
Three Dimensional ◽  
Hydrodynamic Performance ◽  
Cavitation Flow ◽  
Suction Surface ◽  
Double Row ◽  
Suppression Effect ◽  
The Impact

A method of water injection to flow field using distributed holes on the suction surface of hydrofoil is presented in this article to control cavitation flow. Modified renormalization group k–ε turbulence model is coupled with full-cavitation model to calculate periodical cavitation patterns and the dynamic characteristics of the NACA66(MOD) hydrofoil. Water injection is found to be highly effective for cavitation suppression. The cavitation suppression effect of distributed regulation of jet holes and porosities along three-dimensional spanwise hydrofoil is also investigated. The appropriate porosities of single row spanwise jet holes and optimal jet position of double row jet holes are revealed for both cavitation suppression and good hydrodynamic performance. Double row jet holes setting in forward trapezoidal arrangement shows great potential for cavitation suppression and hydrodynamic performance. This research provides a method of water injection to flow field to actively control cavitation, which will facilitate development of engineering designs.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1996 ◽  
Vol 118 (4) ◽  
pp. 835-843 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter: Part II—Unsteady Measurements

1996 ◽  
Vol 118 (3) ◽  
pp. 570-577 ◽  
Author(s):  
K. Brun ◽  
R. D. Flack ◽  
J. K. Gruver
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Incidence Angle ◽  
Angular Position ◽  
Three Dimensional ◽  
Torque Converter ◽  
Operating Conditions ◽  
Plane Flow ◽  
Periodic Fluctuations ◽  
Pump Inlet

The unsteady velocity field found in the pump of an automotive torque converter was measured using laser velocimetry. Velocities in the inlet, mid-, and exit planes of the pump were investigated at two significantly different operating conditions: turbine/pump rotational speed ratios of 0.065 and 0.800. A data organization method was developed to visualize the three-dimensional, periodic unsteady velocity field in the rotating frame. For this method, the acquired data are assumed to be periodic at synchronous and blade interaction frequencies. Two shaft encoders were employed to obtain the instantaneous angular position of the torque converter pump and turbine at the instant of laser velocimeter data acquisition. By proper “registration” of the data, visualizing the transient interaction effects between the stator and the pump, and between the pump and the turbine, was possible. Results showed strong cyclic velocity fluctuations in the pump inlet plane as a function of the relative stator-pump position. Typical percent periodic fluctuations in the through flow velocity were 70 percent of the average throughflow velocity. The upstream propagation influence of the turbine on the pump exit plane flow field was seen to be smaller. Percent periodic fluctuations of the throughflow velocity were typically 30 percent. The effect of the stator and turbine on the midplane flow field was seen to be negligible. The incidence angle at the pump inlet fluctuated by 27 and 14 deg for the 0.065 and 0.800 speed ratios, respectively. Typical slip factors at the exit were 0.965 and fluctuated by less than 1 percent.

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 Parametric Study and Design Optimization ....

10.29007/lbz2 ◽  
2018 ◽  
Author(s):  
Vijaypratap R. Singh ◽  
Mahesh J. Zinzuvadia ◽  
Saurin Sheth ◽  
Ruchir J. Desai
Keyword(s):  
Orthogonal Array ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Impeller Blade ◽  
Cad Modelling

To improve the hydrodynamic performance of the centrifugal pump, in present work a DOE technique Taguchi L9 orthogonal array experiment was carried out to optimize the impeller design parameters. The Navier-Stokes equations for three-dimensional steady flow is solved by computational fluid dynamics (CFD) code. The experimental test result of the original pump was compared with the data predicted from the numerical simulation. The comparison shows the closeness of predicted values with the experimental values, leads to validation of the numerical model under the specific range of operating conditions. Four geometric parameters of impeller were chosen as the variable factors viz. Number of blade, Impeller blade outlet angle, Impeller blade Inlet angle and Impeller blade wrapping angle. According to L9 orthogonal array, nine impellers were modelled using CAD modelling software and CFD analysis is carried out using ANSYS CFX. The impellers were equipped with the same volute during all the simulations. The modelled impellers were simulated by the same numerical method, which has been validated. The best parametric combination for higher efficiency is analysed finally. Results show the improvement of 4.25% higher efficiency compared with the original pump. The geometry selected for this model may be the best one to get the maximum efficiency for such pumps.

Parametric Analysis and Optimization of Leaning Angle in Torque Converters

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Cheng Liu ◽  
Meng Guo ◽  
Qingdong Yan ◽  
Wei Wei ◽  
Houston G. Wood
Keyword(s):  
Angular Position ◽  
Three Dimensional ◽  
Torque Converter ◽  
Hydrodynamic Performance ◽  
Parameter Study ◽  
Cfd Models ◽  
Multi Objective Genetic Algorithm ◽  
Mass Flowrate ◽  
Cubic Model ◽  
Torque Converters

Abstract Torque converters are durable fluid couplings that can provide output torque multiplication. Blade leaning angle represents the angular position of a blade chord with respect to its radial reference line, and it is an important blade variable regarding both hydrodynamic performance and manufacturability of a torque converter. In traditional design processes, blade leaning angles are often determined based on experiences of engineers; hence, this study proposed a design approach using the combination of computational fluid dynamics (CFD) and optimization. Two CFD models were developed to design blade leaning angles. A steady-state periodic CFD model was employed for the parameter study and the optimization, and a transient full three-dimensional (3D) model was performed to study the flow mechanism and evaluate the performance with higher accuracy. Design of experiment (DOE) technique was employed to investigate the relationship between blade leaning angles and hydrodynamic performance, and a reduced cubic model was derived from the results. It was found that blade leaning angles had profound effects on torque converter performance; a large blade leaning angle intensified the flow blockage effect, thus resulting in a lower mass flowrate and torque capacity. Seven torque converters with different blade leaning angles were tested to validate the obtained numerical results, and the test data were found to be in good agreement with the CFD predictions. Finally, the hydrodynamic performance of the base model torque converter was optimized by a multi-objective genetic algorithm.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1994 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stat or at several operating conditions. The flow field is found to be highly three-dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier-Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

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.

Design of experiments to investigate blade geometric effects on the hydrodynamic performance of torque converters

2017 ◽  
Vol 233 (2) ◽  
pp. 276-291 ◽  
Author(s):  
Cheng Liu ◽  
Wei Wei ◽  
Qingdong Yan ◽  
Neal R Morgan
Keyword(s):  
Design Of Experiments ◽  
Factorial Design ◽  
Reaction Force ◽  
Three Dimensional ◽  
Torque Converter ◽  
Fractional Factorial ◽  
Hydrodynamic Performance ◽  
Design Parameters ◽  
Design Variables ◽  
Torque Converters

Torque converters are key components in automatic and hydrodynamic transmissions. Power is transmitted through the reaction force of fluid on cascades; thus, the geometry of the blade is essential to torque converter performance. The traditional one-dimensional blade design approach becomes inefficient for modern torque converter design because torque converters are highly coupled turbomachines and the flow is three-dimensional. In the present research, a novel six-parameter blade camberline design was developed to describe the overall shape of the blade. A full two-level factorial design was conducted with computational fluid dynamics (CFD) simulations on each component to determine the sensitivity of design variables and investigate the relationship between design parameters and hydrodynamic performance. The design variables were reduced from 18 to nine after the screening design. A quarter-fractional factorial design was performed on the selected primary design variables to explore the first-order interaction effects between different wheels. Then a response surface was generated for each component to provide a substitution model for further optimization. A series of torque converters with various design parameters were fabricated and tested to validate the important effects determined in the design of experiments (DOE) process. It is found that CFD in combination with DOE is able to precisely capture the correlation between design variables and hydrodynamic performance. A base torque converter was optimized based on the DOE studies and the result was tested. Pronounced improvement in powertrain performance and fuel economy were observed.

Numerical Study on Flow-Induced Vibration Characteristics of Three-Dimensional Hydrofoil in Cavitating Flow

2019 ◽  
Author(s):  
Chang Wang ◽  
Yuan-qing Liu ◽  
Te-zhuan Du ◽  
Yi-wei Wang
Keyword(s):  
Numerical Study ◽  
Density Ratio ◽  
Three Dimensional ◽  
Simulation Method ◽  
Cavitating Flow ◽  
Vibration Characteristics ◽  
Structural Vibration ◽  
Cavitation Flow ◽  
Flow Induced Vibration ◽  
Cloud Cavitation

Abstract With the increasing demand of higher performance and efficiencies for marine propulsion and hydropower system, structures became more flexible and were subjected to high flow rates. Cavitation-structure interaction has become one of the major issues for most engineering applications. In order to analyze the characteristics of unsteady cavitating flow induced vibration, the cloud cavitation flow over three dimensional NACA66 hydrofoil is studied by numerical simulation in this paper. The cavitating flow is modeled by large eddy simulation method and Zwart cavitation model, and the structural vibration model of three dimensional hydrofoil is established. The numerical calculation of fluid-solid coupling is realized based on ANSYS Workbench. The main dimensionless parameters of three-dimensional hydrofoil cavitation flow-induced vibration are obtained by means of dimensional analysis, including density ratio, cavitation number, Reynolds number, and the frequency ratio of flow to structure. The changes of cavity morphology during the cloud cavitation development of flexible hydrofoil and the flow-induced vibration characteristics under cloud cavitation flow of flexible hydrofoil are analyzed. The results showed that the periodic development of cavitation can be divided into three stages: the growth of attached cavity, the development of re-entrant jet and the shedding of cavity in cloud cavitaion stage. The centroid displacement of the free end of the flexible hydrofoil varies periodically with time at the stage of cloud cavitation. The hydrofoil vibration is affected by the development of cloud cavitation, and the vibration frequency corresponds to the shedding frequency of cloud cavitation.

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