判别水流初生空穴的临界压力

以水的气化压力(Pv)作为判别水流初生空穴的临界压力,以及在此基础上建立的计算初生空穴指数的托马公式σ_1=P_∞-P_v/1/2ρV2,迄今仍在气蚀研究中普遍使用。但是大量的试验结果证实,σ_1常常是不稳定的,即使同一个扰流体本身的σi也可能有高达三倍以上的差别。合理的空穴临界压力不应仅仅只与温度有关,而且还应与杂质及气体含量、压力、流速、史前条件等因素有密切的关系。本文将叙述用抗拉强度(P_T)作为临界压力的物理基础和实际应用的可能性(以公式(?)计算初生空穴指数的初步研究成果。)

The Critical Pressure for Beginning Cavitation in Water Flow

According to the classical cavitation theory, the critical pressure for teginning cavitation is vapour pressure of water, and the cavitation inception number is calculated with the formula (σ_i=P_■-P_v/1/2PV_(■)~2). But a lot of test finding: point out that the σ_i-values are often unsteady When the test condition is varied, for example, the classical comparison test series of the ITTC in 1966, carried through at ore test body in different test facilities in several countries yielded results of upto 300％ differencie The right critical presure depends not only on different temperatur, but also on tptal gas content, fruow velocity, the structure of cavitaion n■clei, s■stem pressure and pr■history of test water, The physical knowielge for tensile streng b of water and the tensile strength as oritical pressure for calculation of cavitation inception number are described in this paper.