普通螺旋桨和大侧斜螺旋桨在两个特定流场中的脉动压力试验研究

本研究通过普通螺旋桨(无侧斜)和大侧斜螺旋桨在空泡水洞两个特定流场(对称非均匀流场和不对称非均匀流场)中诱导的脉动压力试验测量,探讨其不同的脉动压力特性和侧针的减振效果;介绍了为测量脉动压力而建立的传感器和数据采集处理系统。这一根据高速采集储存数据、慢速传送微机处理思想建立起来的Molti-Function系统,有别于通常采用的由高速处理机和磁带记录机组成的脉动压力数据采集处理系统,具有数据采样速度快,无信号失真等优点。本研究发现,大侧斜桨具有降低螺旋桨空化诱导的脉动压力幅值作用,但这一作用的大小与空化数和流场特徵有关;无论是普通桨还是大側斜桨,在不均匀流场中诱导的脉动压力均具如下特徵,即与一阶叶频谐调分量相比,在较大空化数情况,二阶以上叶频谐调分量明显丰富,而在较小空化数情况,则明显变小。本研究认为,在应用简化网格模拟得到的不均匀流场中进行螺旋桨脉动压力测量的比较试验,可克服模拟流场差异带来的测量结果误差,有助于提高实验室的脉动压力测试技术水平。

Experimental Study on Fluctuating Pressure O Conventional and High-Skewed Propellers in Two Specified Flow Field

This study investigates different characteristics of the fluctuating pressure induced by a conventional propeller (without skew) and ahigh skewed propeller in two specified flow field (symmetrical and unsymmetrical) and the effect of the skew on the reduction of the fluctuating pressure. The sensor and the data processing system for the measurement of fluctuating pressure are introduced. This so called Multi-Function System based on the design idea of "quick" sampling and storing data and "slow" transmitting to computer processing, diffenrent from nowadays widely adopted high-speed processing computer and magnet tape recorder, has specially syperiority of high sampling rate and no signal distortion, etc. This study has found that high-skewed propeller can reduce the amplitude of fluctuating pressure induced by cavitating propeller, but the effectness depends on the value of cavitation index and the feature of flow field. This study has also found that the fluctuating pressure induced by aconventional or a high-skewed propeller in non-uniform flow field has such a characteristics that compared with the first order blade frequency harmonic the over second order harmonics obviously tend to be rich in the case of larger cavitation index, on the contrary, poor in the case of smaller cavitation index. It is suggested by this study that the comparative tests of propeller induced fluctuating pressure measurement in a flow field produced by asymplified mesh screen could eliminate the error from the simulalion of flow fleld and is condutive to promoting the level of the fluctuating pressure measuring technique.