Abstract
At present, vortex generators have been extensively used in radiators to improve the overall heat transfer performance. However, there is no research on the effect of vortex generators on the ends of motor coils. Meanwhile, the current research mainly concentrates on the attack angle, shape and size, and lacks a detailed study on the transverse and longitudinal distance and arrangement of vortex generators. In this paper, the improved dimensionless number R is used as the key index to evaluate the overall performance of enhanced heat transfer. Firstly, the influence of the attack angle on heat transfer enhancement is discussed through a single pair of rectangular vortex generators, and the results demonstrate that the vortex generator with a 45° attack angle is superior. On this basis, we compare the effects of different longitudinal distances (2 h, 4 h, and 6 h, h meaning the height of vortex generator) on enhanced heat transfer under four distribution modes: Flow-Up (FU), Flow-Down (FU), Flow-Up-Down (FUD), Flow-Down-UP (FDU). Thereafter, the performances of different transverse distances (0.25 h, 0.5 h, and 0.75 h) of the vortex generators are numerically simulated. When comparing the longitudinal distances, FD with a longitudinal distance of 4 h (FD-4 h) performs well when the Reynolds number is less than 4000, and FU with a longitudinal distance of 4 h (FU-4 h) performs better when the Reynolds number is greater than 4000. Similarly, in the comparison of transverse distances, FD-4 h still performs well when the Reynolds number is less than 4000, and FU with a longitudinal distance of 4 h and transverse distance of 0.5 h (FU-4 h–0.5 h) is more prominent when the Reynolds number is greater than 4000.
Highlights
The results showed that the heat transfer efficiency and friction loss of the fluid with the fin and airfoil vortex generator were higher than those with a smooth channel
The results showed that, in a fluid channel with a large aspect ratio, the heat transfer performance could be enhanced while reducing the pressure loss
Besides the variety of the longitudinal and transverse distance, four different vortex generator distribution modes are shown in Figure 1e, which are specified as Flow-Up (FU), Flow-Down (FD), Flow-Up-Down (FUD), Flow-Down-UP (FDU)
Summary
The motor is widely used in ship, municipal, electric power, port handling, and other fields, with broad development prospects and considerable market capacity. Used the k − ε turbulence model to explore the heat transfer and pressure drop characteristics of vortex generators with various attack angles, and found that the maximum increases in Nusselt number and friction coefficient are 269% and 10.1 times higher than those of smooth tubes, respectively. With the help of computational fluid dynamics (CFD) software, the effect of different distribution types of the vortex generator on the heat transfer effect can be simulated, and the temperature change at the end of the coil and the pressure loss before and after the installation of the vortex generator can be analyzed. The best distribution type can be obtained, and the mechanism of heat transfer enhancement by turbulence at the end of the coil can be revealed Through these explorations, this paper can provide a feasible idea for the design and application of the motor in industrial manufacturing
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