格栅对喷水推进器进水流道流动和船舶推进性能影响

Effect of Inlet Grid on Duct Flow Performance and Waterjet Propulsion Performance

针对船舶喷水推进中,进水流道格栅的有无及疏密会对进水流道流场及船舶推进性能产生怎样影响的问题,采用计算流体力学(Computational fluid dynamics,CFD)数值试验的方法分别对某喷水推进快艇无格栅、有3根格栅、有8根格栅的同一流道的'船+格栅+进水流道+喷水推进泵'的流场进行计算,得到三种情况下该艇的稳定航速,并求出相应航速下进水流道的效率、流量、出口流场的不均匀度等性能参数。通过对三种情况下各项参数的对比可知,在相同的主机转速下,加装格栅会使流道效率降低、出流不均匀度降低,会使航速降低、流过喷水推进器的流量降低、推进效率降低;格栅加密会加大上述性能参数的降低幅度。从机理角度解释上述参数变化的物理本质。研究结果表明,格栅会降低喷水推进器进水流道的流动性能,同时也会降低船舶推进性能。

The inlet duct grids and their spaces between them make significant influence on the flow in waterjet inlet duct and propulsion performance. Three flow fields in the same inlet duct with no grid, three grids and eight grids are calculated by computational fluid dynamics method, and three ship speeds according with inlet duct efficiency, mass flow rate, and non-uniformity of duct outlet are received. The numerical results are compared and indicated that at the same rotation rate of main engine the installation of inlet grids reduce the inlet efficiency, non-uniformity of duct outlet, the ship speed, mass flow rate, and propulsion efficiency. Reducing grid spaces brings greater reduction of these parameters. The physics essences of the changes of parameters are analyzed from mechanism point. The study indicates that inlet grids can reduce the duct flow performance and also reduce watcrjet propulsion performance.