Study on the drag reduction performance of high-temperature exhaust pipe by spray cooling

Abstract

The drag of the exhaust pipe greatly influences the engine power performance of an engineering vehicle. The engine power performance would decrease significantly when the exhaust drag is large. The drag reduction effect achieved by the existing drag reduction is relatively weak; thus, based on spray cooling, drag reduction technology is introduced to solve this problem. The present study aims to determine the influence of spray parameters on drag reduction using an electric heating test bench and to clarify why spray significantly reduces drag using numerical simulations based on Discrete Phase Modeling (DPM). The obtained results prove that increasing the flow value in the test spray flow range of 12–24 ml/s can significantly improve the drag reduction performance. When the spray inclination increases from 45° to 90°, the drag reduction remains, in the beginning, unchanged and then decreases. Under the synergistic effect of the frictional resistance reduction and the dynamic pressure reduction, the resistance downstream of the spray location is significantly reduced. Compared with the existing drag reduction, the spray drag reduction has obtained the ultimate drag reduction effect, and the drag reduction rate is as high as 90 %. To conclude, this research will help promote the application of spray drag reduction to engineering vehicles.