旋進(jìn)射流噴嘴的頻率及流場特性研究

在圓筒套管內(nèi)設(shè)置一塊孔板構(gòu)成旋進(jìn)射流噴嘴,由此獲得持續(xù)穩(wěn)定的旋進(jìn)射流,研究了噴嘴最優(yōu)的結(jié)構(gòu)參數(shù)。用熱線風(fēng)速儀測量出口射流的速度并進(jìn)行功率譜分析,得到旋進(jìn)射流的頻率及流場特性。研究表明,旋進(jìn)射流具有較高的紊流強(qiáng)度,速度場沿徑向的分布趨向平緩,其進(jìn)動(dòng)頻率隨流量增大而加快,噴嘴的尺寸和結(jié)構(gòu)對射流進(jìn)動(dòng)有影響。
A self2sustained uninterrupted precession motion is generated in a precessing jet nozzle consisting of a cylindrical tube added to an orifice and the optimal configuration parameters for the nozzle are presented. The flow field of the precessing jet is obtained by a hot wire anemometer at the nozzle exit and the precession frequency is identified from a power spectrum density analysis to the velocity signal. It is shown that the precession frequency increases with the increment of flow rate (Reynolds num2 ber) . The exit profile of mean velocity in the precessing jet is far wider spread and the turbulence intensity is much higher com2 pared to that of the in2line jet. It is also indicated that the size and configuration of the nozzle also have a significant influence on the precession motion of the exit jet.