水翼间隙非定常涡空化流动的试验和数值研究

Experimental and numerical investigations of unsteady tip leakage vortex cavitating flows around a hydrofoil

采用高速全流场显示技术对水翼叶顶间隙区域非定常旋涡空化流动进行观测,并提出一种旋涡空化模型来对空化流动进行计算.研究结果表明,提出的空化模型可以较好地捕捉非定常泄漏涡空化.此外,基于计算结果对水翼前缘云状附着空化与间隙涡空化的相互作用进行重点分析.结果表明,附着空化的发展和脱落会引起水翼叶顶附近迎背流面压力差值的变化,从而导致叶顶区域射流剪切层空化具有显著的非定常特性;附着空化末端闭合处的压力波动会造成泄漏空化涡强度的波动;附着空化的断裂所引起的吸力面局部高压会导致泄漏空化涡强度的显著降低.

Experimental and numerical investigations were conducted to highlight the unsteady tip leakage vortex cavitation flow in a hydrofoil tip region. The experiments were conducted in a closed cavitation tunnel,which a high-speed-camera had been put into using to observe the cavitation patterns. A new cavitation model,which takes into account the effects of vortex on mass transfer process in cavitation,is utilized for the computations of developed tip leakage vortex cavitating flow. Good agreement is observed between the numerical predictions and experimental observations. The results show that unsteadiness of the leading edge attached cavity would significantly change the pressure on the suction side,which is the main reason for the unsteadiness of the shear layer cavitation. The pressure fluctuation at the end of the attached cavity would induce the change of the tip leakage vortex circulation. Furthermore,the breakup of the leading edge cavitation would induce a local high pressure in the suction side,resulting in the decreasing of the circulation of the tip leakage cavitating vortex.