Improving Spool Valve Operating Effort Using CFD

Hydraulic oil flow and flow induced forces inside hydraulic spool valves have been studied using a commercially available Computational Fluid Dynamics (CFD) software package with an aim of improving hydraulic spool valve operating efforts. The main objective is to investigate flow induced forces on the spool with a range of different geometries or operating conditions and therefore to minimize or utilize their effect on spool effort. This CFD problem was treated as incompressible, turbulent, steady and adiabatic or isothermal. Integration of solved pressure field from a commercial CFD solution over related a valve component surface area was used to integrate the desirable flow induced forces. Additional viscous drag forces on the spool effect on total spool operating effort have also been investigated. The focus in this article is mainly based on studies for open center flow type four-way spool valves in cases such that the hydraulic oil flow direction towards spool. Some other spool metering cases will also be presented. CFD results are compared to experimental results with overall good correlation.