全工况下双流道泵内流三维PIV测量

为了揭示双流道泵从零流量点到大流量点内部流动的变化规律,采用粒子图像测速仪对1个比转数为1107的双流道泵在8个工况下的内部流动进行了测量．采用基于光纤制作的外触发同步系统和三维等效标定方法等关键技术来保证3D PIV的测试精度．根据速度三角形,采用Visual C++2005编写了PIV速度分解程序,将测量的叶轮内的绝对速度分解成圆周速度相对速度．研究结果表明:叶轮流道内的流动并未随着流量的减小出现大范围的旋涡,仅当流量小于04Qd以后在叶轮出口靠近吸力面侧出现1个旋涡,并且随着流量的减小该旋涡越来越明显;另外,随着流量的减小,蜗壳扩散段上的绝对速度值逐渐减小,且当流量小于 02Qd时扩散段开始出现旋涡;在叶轮出口靠近隔舌处的区域上绝对速度值随着流量的减小先增大后减小,在02Qd工况下速度值达到最大;关死工况下叶轮和蜗壳内都存在着明显的旋涡和回流,泵内流态最差．

3D PIV measurement of flow in double-channel pump under overall operating conditions

The inner flow characteristics in a double channel pump were measured under eight flow rates with a particle image velocimetry (PIV). To guarantee the accuracy of three dimensional PIV measurements, a few key techniques, such as the optical fiber based external trigger synchronization system and three dimensional equivalent calibration methods, were applied in the measurements. A Visual C++2005 code was composed to obtain the relative velocity components from the absolute ones measured according to the velocity triangle. The results showed that one large scale doesnt appear in a flow passage of the impeller until the flow rate as low as 04 time the design flow rate Qd.. Moreover, this vortex gets more evident with decreasing flow rate. As flow rate decreases, the absolute velocity in the volute diffuser is decreased as well. A vortex doesnt occur there until the flow rate is reduced to 02Qd. The absolute velocity gets maximum values at the flow rate of 02Qd. There exist dominated large scale vortices in the impeller and volute at the shut off condition, suggesting the poorest flow condition has emerged there.