进水池形状对吸入涡影响试验研究

为了改善进水池附近的流态,避免吸入涡进入喇叭口,首先以不同淹没深度和不同流量对开敞式进水池进行高速摄影和PIV试验,根据测试的流态提出相应改善措施,然后对矩形进水池和矩形进水池加底部十字架2种方案进行试验,观察并对比其消涡效果.结果表明,相对于开敞式进水池的方案,矩形进水池方案可以使喇叭口处的流态得到改善,并将前者的允许最小淹没深度降低,即在同等条件下改善了旋涡的表面涡纹状态;然后对矩形进水池方案加十字架后,进一步减小了旋涡的影响,并再次降低了允许最小淹没深度,由0.90D降低到0.70D,且改善了旋涡的表面涡纹状态.研究结果对于允许最小淹没深度的改进、降低泵站进水池的工程造价方面具有参考意义.

Experimental investigation into effects of sump shape on suction vortex

Serious vortices in pump sumps can lead to cavitation in a pump, subsequently the pump characteristics are affected in operation. In order to improve the flow regime in a sump and prevent vortices from entering into the bell-mouth, a series of high-speed photography and PIV experiments are carried out at different submerged depths and flow rates in an open sump firstly, then, according to visualized flow patterns, two measures, namely a rectangular sump with and without bottom cross, are put forward to improve the flow pattern; finally, their effects on vortex elimination are observed. The results show that the rectangular sump without bottom cross is able to improve the flow regime in the sump and to reduce the minimum submerged depth, the surface spiral vortex intensity can be reduced under the same operating condition. For the rectangular sump with bottom cross, the effect of vortex is suppressed further, and the minimum submerged depth is reduced once more and the surface spiral vortex intensity is dampened. This study makes significant sense in lowering allowable submerged depth and reducing engineering costs of pump sump.