Cavitation Phenomena and Performance of Oil Hydraulic Poppet Valve : 2nd Report, Influence of the Chamfer Length of the Seat and the Flow Performance

Abstract

The influences of the chamfer length of the valve seat on the flow performance and the cavitation phenomena of an oil hydraulic poppet valve are studied experimentally using the half cut model. It is made clear that the discharge coefficient becomes maximum when the ratio of the chamfer length S to the restriction height h is a specific value within 1≤S/h≤3 in the case of a diverging flow, and S/h≤1 in the case of a converging flow, if the valve lift x^^- and Reynolds number R^*_e are fixed. The critical cavitation number K_c also becomes maximum in the same range of S/h as the above. In the case of a diverging flow with chamfer length of S = (1 2.5)h, a periodic flow turbulence occurs at the restriction under some pressure conditions, and it induces an unusual sound noise like a whistling with resonant vibration of the oil column in the pipe line.