旋進射流噴嘴的頻率及流場特性研究

在圓筒套管內設置一塊孔板構成旋進射流噴嘴,由此獲得持續穩定的旋進射流,研究了噴嘴最優的結構參數。用熱線風速儀測量出口射流的速度并進行功率譜分析,得到旋進射流的頻率及流場特性。研究表明,旋進射流具有較高的紊流強度,速度場沿徑向的分布趨向平緩,其進動頻率隨流量增大而加快,噴嘴的尺寸和結構對射流進動有影響。
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.