On the Stability of Supercavity with Angle of Attack

Abstract

SUMMARY Research on the supercavity stability is not only the focus question as a physical phenomenon in the field of the supercavity flows, is but also the basis of studying the control of the supercavitating flows and their vehicles. Angle of attack (AOA) is one of the most important control variables that can maintain and control the supercavity dimensions and its vehicle by changing the drag coefficient and the separation point of supercavitating flows to produce an effect on the force of supercavitating vehicle. However, the disturbances caused by angle of attack or other factors follow and influence the supercavity stability, and in this case, the stability mechanism of supercavity with AOA is different from one without AOA. Hence, the gravity and AOA models of supercavity are respectively established, and the supercavity stability is analyzed combining with Logvinovich model by researching the supercavity after disturbance in this paper. FFT is used to analyze the numerical results to get the frequency characteristics of the pulsation supercavity with and without AOA. It demonstrates that the dominant pulsation frequency of supercavity is irrelevant to the external disturbance excitation. Considering this point, the gas dynamics parameterE , the ratio of the vapor cavitation number v V to the ventilation cavitation number c V , is taken as the stability criterion parameter for the supercavity with the given AOA. The corresponding critical valuesE are obtained numerically for the different AOAs. On this basis, comprehensive consideration of the elastic parameter E and AOA D , the new stability criterion is formulated using the nonlinear least square method for supercavity with AOA.