Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Robinette, Darrell; Anderson, C. L.; Blough, Jason R.

doi:10.5772/45793

Cited by 5 publications

(2 citation statements)

References 9 publications

(16 reference statements)

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“…hydraulic pump, torque converter, direction gear sets, friction between belt and variator accounts for about 14%, 6%, 3% and 10% respectively [22], which is shown in Fig.6. The efficiency of torque converter increases proportionally to output/input speed ratios from zero at stall to 100% when the turbine and impeller locked together [26].. However, CVT offers a great potential for the efficiency improvement by introducing the electrified variator control system and optimized belt pressure control strategy, which are validated by both of simulation and experiment.…”

Section: Economy Performancementioning

confidence: 93%

A comparative study energy consumption and costs of battery electric vehicle transmissions

2016

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Despite the long-term benefit of battery electric vehicles (BEVs) to customers and environment, the initial cost and limited driving range present significant barriers for wide spread commercialization. The integration of multi-speed transmissions to BEVs' powertrain systems in place of fixed ratio reduction transmissions is considered as a feasible method to improve powertrain efficiency and extend limited driving range for a fixed battery size. The aim of this paper is to enable the researchers or BEV manufacturers, especially for transmission systems, to estimate whether their products are worthwhile for the customer in terms of the price/performance relationship of others' design solutions. To do so a generic battery electric vehicle is modelled in Matlab/Simulink® to predict motor efficiency and energy consumption for single reduction, two speeds Dual Clutch Transmission (DCT) and simplified Continuous Variable Transmission (CVT) equipped battery electric vehicles. A credible conclusion is gained, through experimental validation of single speed and two speeds DCT scenarios and reasonable assumptions to support the CVT scenario, that both two speeds DCT and simplified CVT improve the overall powertrain efficiency, save battery energy and reduce customer costs. However, each of the configurations has unique cost and energy consumption related trade-offs.

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Section: Economy Performancementioning

confidence: 93%

A comparative study energy consumption and costs of battery electric vehicle transmissions

2016

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“…Liu et al (Liu et al, 2018a;Liu et al, 2019) studied the influence of the stator blade shape on the cavitation process of a hydraulic torque converter and found that cavitation is directly related to the internal mass flow rate. Robinette et al (Robinette, 2007;Robinette et al, 2008a;Robinette et al, 2008b) investigated the effects of torque converter design and operating conditions on the onset of cavitation during vehicle launch using a nearfield acoustical technique. From their numerical results, Dong et al (Yu et al, 2002) determined that the cavitation on the stator leading edge grew in size with increasing pump speed, resulting in severe performance degradation in the torque converter.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of transient cavitation characteristics of valve-controlled liquid-filled hydrodynamic coupling

Cui,

Zhang,

et al. 2023

Front. Energy Res.

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In high-power impeller industries, valve-controlled liquid-filled hydrodynamic couplings are widely used in the soft startup of heavy-duty scraper conveyors for mining. However, the water circulation speed in internal flow fields is higher at lower speed ratios, making the hydrodynamic couplings prone to severe cavitation, which further results in severe performance degradation, noise, vibration, or even erosion failure. Meanwhile, because a hydrodynamic coupling is a piece of closed-loop multicomponent turbomachinery, internal transient cavitation flow behavior cannot be easily controlled. To reasonably predict the characteristics of cavitation and its influence on the working performance of the hydrodynamic coupling, a high-quality structured mesh model of the internal flow field for an impeller was established. Considering the periodic structural characteristics of the impeller, a scale-resolving simulation turbulence model was combined with a Rayleigh–Plesset cavitation model to establish a single-cycle hydrodynamic coupling calculation model. The cavitation distribution characteristics and torque transmission of the flow field under different working conditions were obtained, and the effect of cavitation on the soft startup performance was analyzed. The results demonstrated that cavitation in the hydrodynamic coupling mainly occurred under low speed ratios. The degree of cavitation decreased as speed ratio increased. The worst-case scenario for cavitation occurred when the speed ratio was zero. Most of the cavitation bubbles were generated at the tip of the blades, resulting in unstable variation in torque characteristics and deterioration of the working performance of the hydrodynamic coupling. The analysis reveals that the cavitation process in the impeller is highly unstable and periodic, and the cavitation development near the tip of the blades occurs in four stages: birth, growth, separation, and disintegration. The generated steam accumulates in the inner ring of the impeller. Therefore, a method for accurately predicting the cavitation characteristics of hydrodynamic couplings based on high-precision technology is proposed, and a theoretical basis for coupling design and cavitation suppression technology is provided.

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Automatic Transmissions: On the Relationship Between the Cavitation Modes of the Torque Converter and High-Frequency Resonant Torsional Oscillations of Mechanical Components

KRASNEVSKIY¹

2022

MMMM

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Based on the analysis of foreign publications, a number of new scientific results are presented in the field of hydrodynamics of working fluid flows in torque converters (TC) of automatic hydromechanical transmissions (AHMT), including cavitation in TC, which were obtained using the new CFD (Computational Fluid Dynamics) technology as part of research to reduce the vibroacoustic loading of AHMT. CFD modelling methods have shown that cavitation in a TC, along with the creation of noise and vibration, significantly degrades its characteristics (in the example given, the transformation coefficient is by 18.1 %, efficiency is by 5.8 %, turbine torque is by 20.3 %), and also creates high-frequency oscillations in a wide range that can resonate with the natural frequencies of the AHMT components. The influence of structural and operational factors on cavitation is investigated. The greatest cavitation occurs on the blades of the TC stator in stop mode when the car accelerates from a standstill. The results of CFD modelling are in good agreement with experimental data. CFD technology has become an effective tool for optimizing the design of an automotive TC, its blade system, flow part, visualization of internal flows, study of the mechanism of occurrence and impact of cavitation. The analysis of methods of attenuation of cavitation is carried out, including the selection and maintenance of the value of the TC recharge pressure. The presented provisions in Russian are published for the first time.

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Development of a Dimensionless Model for Predicting the Onset of Cavitation in Torque Converters

Cited by 5 publications

References 9 publications

A comparative study energy consumption and costs of battery electric vehicle transmissions

A comparative study energy consumption and costs of battery electric vehicle transmissions

Numerical simulation of transient cavitation characteristics of valve-controlled liquid-filled hydrodynamic coupling

Automatic Transmissions: On the Relationship Between the Cavitation Modes of the Torque Converter and High-Frequency Resonant Torsional Oscillations of Mechanical Components

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