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

Abstract

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.

Experimental Research Concerning Hydrodynamic Clutches Controlled by Increasing Distance Between Rotors

“…Schweitzer and Gandham [10] conducted an analysis of a working fluid flow within the HTC using CFD methods, and the results of the numerical calculations are verified on a test station using laser Doppler velocimetry LDV. Similar research is shown in the studies [11,12,13,14,15,16,17]. The study [18] shows an optimization of the selection of the entry angle for a pump rotor and the entry angle for a turbine rotor in a HTC.…”

Calculation and analysis of thermal flow field in hydrodynamic torque converter with a new developed stress-blended eddy simulation

“…Therefore, according to a certain time step size (0.0005 s), the pump and turbine rotate along the gird interface during the calculation. In addition, as shown in Table 2, the other parameters of the CFD model in the ANSYS fluent were set (Liu et al, 2020). The solution was assumed to have converged when the monitored turbine torque tended toward stability, and the defined residuals for all equations were less than 1E-4.…”

“…The performance prediction was the key task for HTC design in industry, so another HTC was presented to further testify SBES models, as shown in Figure 16. This product, whose geometry could be found in our previous study (Liu et al, 2018c(Liu et al, , 2020 in Figures 16(a), 16(b) and 16(c), was subjected to the numerical simulation, and the external characteristics could be extracted from the simulation results. Before the calculation, the grid dependence was investigated; however, we did not include it in this study due to space/word constraints.…”

“…In Figure 16(d) and 16(e), the simulation value is highly fitting to the experimental value, absolute error of external characteristic is around 5%. Compared with the traditional calculation method, the new calculation result has a great improvement (Liu et al, 2020).…”