Numerical simulation and animation of oscillating turbulent flow in a counterbalance valve

This paper reports the results of numerical simulation of oscillating flow in the complex flow passage of a hydraulic counterbalance valve. A counterbalance valve, when correctly applied to a hydraulic circuit, modulates the flow of oil when lowering a load, with a crane for example, to prevent an overrunning condition. Under some unique operating conditions, they produce a high frequency, monotone noise that can be characterized as a squeal. The intensity of the noise depends on the characteristics of the valve. The numerical computation was carried out by using the commercial computational fluid dynamics code FiDAP. A two-dimensional axisymmetric flow model was developed to simulate the operation of the valve. With the use of both structured and unstructured meshes, the complex geometry that forms the flow path through the valve was discretized. Equations for the conservation of mass and momentum were solved. The simulation of turbulence in the unsteady flow was carried out using the Launder eddy-viscosity model. The animation of computed flow field showed a high frequency of oscillation in the flow that agrees well with the experimentally determined main frequency of the squealing noise