This paper deals with the cavitation characteristics of poppet valves, especially the pressure distribution on the valve face and rod, the valve thrust coefficient and the cavitation noise of various valves which are obtained by changing the combination of the valve face angle 2a and the valve seat width s.
The results obtained are as follows:
1) In case of s/d = 0, 0.25 (d: inlet diameter of a valve), even in a condition of the most violent cavitation, the minimum pressure on the valve face is higher than atmospheric pressure.
However, for s/d different from these values, the pressure indicates very low values.
2) In case of a valve with a combination of s/d = 0 and valve face angle 2α = 60°; in cavitating flow, there is little difference between the thrust coefficient f obtained from the pressure distribution along the valve face and the thrust coefficient f_m given by the momentum theory, irrespective of the sectional area A(H) of annular passage way of the valve and the upstream pressure p₁. In case of 2α= 30°, 50°, there is a little difference between f and f_m
3) In a condition of the most violent cavitation, f'_t for four kinds of valves with s/d =0.25, 0.5, 1 and 2 are approximately the same as that for s/d =0 for various values of A(H). But in the flow of very small A(H), it is greatly afected by the value of: i/d.
4) In each combination of s/d = 0, 0.25 and 2α = 30°, 50°, 60°, the overall sound pressure level due to cavitating flow increases with increasing back pressure p₂ from a minimum one.
For poppet valves of different combinations than those, however, it decreases with increasing p₂.

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