Experimental Research On The Influence Of The Distence Between Vane And Impeller In The Hydrodynamic Performance Of Axial-flow Waterjet With Front Guide Vane

The axial flow waterjet with front lead vane is a fresh type with the development of waterjet propulsion.Compared with the axial flow waterjet with rear guide vane,the axial waterjet with front guide vane has high flow,low vibration,low noise and a series of advantages.Today people pay more and more attention to the axial flow waterjet with front guide vane.It has a wide application prospect in underwater jet propulsion.The axial flow waterjet with front guide vane arranges guide vane in front of the impeller.It can act as a shaft support.This structure will bring more flexible installation.At work,the front guide vane cause the flow to be pre-swirl.The liquid flows into the impeller with negative pre-swirl.The impeller generates the head by correcting negative pre-swirl of the flow.The axial waterjet with front guide vane's hydrodynamic features are high flow,small vibration,low head and noise.Compared with the traditional axial flow waterjet,axial flow waterjet with front guide vane has many advantages in the underwater vehicle application.At present,there is little facilities or method can accurately measure the hydrodynamic performance of axial flow waterjet with front guide vane.The traditional hydrodynamic performance test method and platform can not obtain its hydrodynamic performance accurately.According to the axial flow waterjet with front guide vane's hydrodynamic characteristics,On account of the hydrodynamic property experimental platform of axial-flow waterjet.By improving the test method and redesign facility,form the first series of experimental facility on accurately obtaining the impact of the axial-flow waterjet with front guide vane's hydrodynamic capability and the perfomance by distance between guide vane and impellor in China.According to the hydrodynamic characteristics of axial flow waterjet with front guide vane,study the mothed of simulation test.Accomplete the numerical calculation of this form of axial flow waterjet with lead guide vane's hydrodynamic performance in three kinds distance 0.1D,0.2D,0.3D(D—diameter of pipe)between lead vane and impeller.The influence of distance between guide vane and impeller on the axial flow waterjet with front guide vane's hydrodynamic performance is got.Subsequently,the physical model test is studied.The hydrodynamic curves at three different distances are obtained.The experimental results are compared with those calculated by numerical calculation.Both conclusion is identical.The effectiveness of the experiment's results is validated.And the influence of the distance on the hydrodynamic performance of the axial waterjet with front guide vane is mastered.The principle is that the farer the distance,the lower the waterjet's head and performance.The reason is that the greater the distance is,the smaller the minus prewhirl is.The work ability of impeller is worse and educe head and efficiency.Distance of 0.1D(D—diameter of pipe)is the design of waterjet.The minus prewhirl and the impeller's angel are identical.At this time,the impeller's head-lifting capacity is stronger.When the distance gradually increased to 0.3D(D—diameter of pipe),the setting angle of the guide vane remains unchanged and the negative pre-swirl angle of the impeller is smaller and smaller.This lead to the impeller's head-lifting capacity weakening.The hydrodynamic performance of the axial flow waterjet with front guide vane gradually decreases.Therefore,the matching of negative pre-swirl angle of the flow and the impeller's angle is closely related to the lifting of waterjet's hydrodynamic performance.