Numerical Analysis of Pressure Drop and Cavitation Effects in Vehicle Steering System

In the pressure hose, pressure of fluid is decreasing due to many factors such as friction resistance (f) in inner wall, geometrical resistance factors like circular deformation rate (C.D.R), bending degree, curvature, sectional expansion-contraction ratio and etc.. And the fluid in return hose experiences a high pressure condition within a short time, when sudden impact is delivered on the gear box. At this time, cavities appear in lower static pressure region like inner radius of a bended pipe and hose system at this moment. That happens, because oil pressure remains lower than saturated vapor pressure at specific temperature. These cavities cause pressure drop, noise, vibration and damage hydraulic components. Those factors make both performance of vehicle movement and fuel-consumption rate worse. In experiment, pressure drop, vapor pressure and many properties of power steering fluid are measured. And we verified pressure drop coefficients for various shapes and cavitation phenomenon by using C.F.D (Computational Fluid Dynamics) code and compared this with pressure drop test. Therefore, objective of this paper is to reduce energy consumption of steering system as well as to find a design technique with numerical evaluation for good performance.