Masami Ochiai

Characteristics of Flow Through Throttling Valve Undergoing a Steep Pressure Gradient

Abstract This paper presents predictions and measurements of the structures of cavitation flow inside the throttling valve. The three-dimensional Navier-Stokes equations in a moving reference frame are solved on tetrahedral meshes. A sliding mesh technique is utilized to characterize unsteady interactions. The accuracy of the predicted flow fields is evaluated by comparison to measurement results taken with a high-speed camera. Results show that the pressure distribution inside the throttling groove is sensitive to the valve port configuration and flow direction. Bubbles form near the side wall of the groove on the throttling edge where, in the case of flow into the throttling groove, the pressure is at a minimum. With the increase of the pressure gradient bubbles saturate the flow. Noise spectrum analysis indicates that the noise level induced by cavitation is determined by the number and size of the bubbles passing through the valve grooves.