A Mathematical Model for Simulation of Flow Rate and Chamber Pressures in Spool Valves

Abstract

In this paper, a mathematical model to simulate the pressure and flow rate characteristics of a spool valve is derived. To improve the simulation accuracy, the discharge coefficient through the spool valve ports is assumed to be a function of both the Reynolds number and the orifice geometry rather than treating it as a constant. Parameters of the model are determined using the data obtained by computational fluid dynamics (CFD) analyses conducted on two-dimensional axisymmetric domains using ANSYS Fluent 15® commercial software. For turbulence modeling, shear stress transport (SST) k–ω model is preferred after a comparison of performance with the other available turbulence model options. The resulting model provides consistent pressure and flow rate estimations with CFD analyses and a smooth transition between different geometrical conditions. The ultimate aim of this study is to fulfill the need for a model to precisely determine the geometrical tolerances of spool valve components for optimum performance. Estimations of the developed model is compared with the experimental data of a spool valve, and the model is proved to be able to accurately estimate the maximum leakage flow rate, the pressure sensitivity, and the shapes of leakage flow/load pressure curves.

An indirect flow measurement based high-precision slide valve grinding mechanism for hydraulic servo valve

“…In this study, the spool valve overlaps L i , as shown in figure 2, refers to the fit dimension for the working edges of the spool shoulder and the corresponding valve sleeve square hole along the axis, when the spool is in the middle of the valve sleeve [25,26]. Such a micrometer level overlap would introduce nonlinearities between the flow rate and valve spool displacement [27,28].…”

Throttling characteristics prediction methodology for combined grooves in directional spool valves under variable flow rates

“…Lisowski et al [ 13 ] demonstrated that considering both the flow rate and spool position enabled more accurate estimation of the flow coefficient. Afatsun et al [ 14 ] proposed the model for the simulation of the flow rate and the pressure, where the flow coefficient depended on both the Reynolds number and the spool geometries. But the studied valve had a simple spool without grooves.…”