水垫塘不同水流结构区掺气浓度分布规律试验研究

为了得到水垫塘局部掺气浓度分布规律,减少过流边壁空蚀破坏的发生,采用水力学模型试验的方法,将水垫塘内水体进行水流结构分区,通过改变泄流流量、水流入射角度、水垫深度三个条件,实测水垫塘不同水流结构区掺气浓度值,研究气体在不同水流结构区的运动机理。对试验所测数据进行整理得到水垫塘不同水流结构区掺气浓度分布曲线,且不同的水力条件与其拟合近似为二次曲线关系。通过分析得到水垫塘不同水流结构区掺气浓度分布规律如下:各水流结构区掺气浓度随泄流流量增大而增大;射流与附壁射流区紊动掺混随泄流流量增大而更加剧烈;掺气浓度随水垫深度增大而减小;淹没射流区与旋滚区掺气浓度随水流入射角度增大而减小,附壁射流区掺气浓度随入射角度增大而增大,但变化不明显。

Experimental study on aeration density distribution law in different flow structural regions of water cushion pool

In order to obtain the distribution law of local aeration density in the water cushion pool and reduce the occurrence of cavitation damage on the flow-passingside-wall， the water body in water cushion pool is divided into several flow structural regions with the method of hydraulic test. Through changing the three conditions， i.e. discharging flow rate， incidentangle of water flow and water cushion depth， the aeration density values of different flow structural regions in water cushion pool are measured， and then the air movement mechanisms in different flow structural regions are studied. The aeration density curves of different flow structural regions in water cushion pool are obtained through sorting-out of the measured data from the test and then approximately fitted with different hydraulic conditions into the relations of quadratic curve. In accordance with the relevant analysis， the law of the aeration density distribution of different flow structural regions in water cushion pool is obtained， viz. the aeration densities of all the flow structural regions are to be increased along with the increase of the discharging flow rate； the turbulent mixing in the jet and wall-attached jet area is to be more turbulent along with the increase of the discharging flow rate； the aeration density is to be decreased along with the increase of the water cushion； the aeration densities of both the submerged jet area and the rolling area are to be decreased along with the increase of the incidentangle of water flow； the aeration density in the wall-attached jet area is to be increased along with the increase of the incidentangle of water flow， but no any obvious changes are there.