Two types of poppet valves were tested, one is a poppet with a sharp-edged seats, and the other is that with a chamfered seat. During the tests, the effects of backpressure and poppet lift on flow characteristics were...Two types of poppet valves were tested, one is a poppet with a sharp-edged seats, and the other is that with a chamfered seat. During the tests, the effects of backpressure and poppet lift on flow characteristics were considered. Cavitation inception was detected by the appearance and rapid growth of a particular low frequency component of the outlet pressure fluctuation of valve when cavitation occurs. Experimental results show cavitation, back pressure, valve opening and its geometrical shape have significant effects on the flow characteristics of valve. The flow coefficient of throttle with water used as working medium is 0 85～0 95 when there is no cavitation. The pressure drop of flow saturation decreases with the increasing of poppet lift. The sharp-edged throttle has stronger anti-cavitation ability than the chamfered one.展开更多
Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon i...Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon in south Asia is derived. The stress is on the influence of the flows on the formation,transformation and intensity of the monsoon in south Asia. The results show that the influence on the monsoon in south Asia is significantly different among the primary shear flow, the basic flow and the secondary shear flow.展开更多
文摘Two types of poppet valves were tested, one is a poppet with a sharp-edged seats, and the other is that with a chamfered seat. During the tests, the effects of backpressure and poppet lift on flow characteristics were considered. Cavitation inception was detected by the appearance and rapid growth of a particular low frequency component of the outlet pressure fluctuation of valve when cavitation occurs. Experimental results show cavitation, back pressure, valve opening and its geometrical shape have significant effects on the flow characteristics of valve. The flow coefficient of throttle with water used as working medium is 0 85～0 95 when there is no cavitation. The pressure drop of flow saturation decreases with the increasing of poppet lift. The sharp-edged throttle has stronger anti-cavitation ability than the chamfered one.
文摘Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon in south Asia is derived. The stress is on the influence of the flows on the formation,transformation and intensity of the monsoon in south Asia. The results show that the influence on the monsoon in south Asia is significantly different among the primary shear flow, the basic flow and the secondary shear flow.
