Abstract
As an important overcurrent component in a waterjet propulsion system, the inlet passage is used to connect the propulsion pump and the bottom of the propulsion ship. The anticavitation, vibration, and noise performance of the waterjet propulsion pump are significantly affected by the hydraulic performance of the inlet passage. The hydraulic performance of the inlet passage directly affects the overall performance of the waterjet propulsion system, thus the design and optimization method of the inlet passage is an important part of the hydraulic optimization of the waterjet propulsion system. In this study, the hydraulic characteristics of the inlet passage in the waterjet propulsion system with different flow parameters and geometric parameters were studied by a combination of numerical simulation and experimental verification. The model test was used to verify the hydraulic characteristics of the waterjet propulsion system, and the results show that the numerical results are in good agreement with the test results. The numerical results are reliable. The hydraulic performance of the inlet passage is significantly affected by the inlet velocity ratio. There is a certain correlation between the hydraulic performance of the inlet passage and ship speed, and the hydraulic performance of the inlet passage is limited by ship speed. The geometric parameters of the best optimization case are as follows: the inflow dip angleαis 35°, the lengthLis 6.38D0, and the upper lip angle is 4°. The optimal operating conditions are the conditions of IVR 0.69–0.87.
Highlights
Due to the influence of wave parameters, length of the ship, wind resistance on the hull, etc., the stall will occur when the ship is running. ere are two types of ship stalls, including wind wave stall and rotating stall [21, 22]
Cavitation is easy to occur in the inlet passage under high inlet velocity ratio (IVR) condition, and the outflow uniformity of the inlet passage is better. e comprehensive hydraulic performance of the inlet passage is excellent when the IVR is between 0.78 and 0.96
The hydraulic characteristics of the inlet passage in the waterjet propulsion system with different flow parameters and geometric parameters were studied by a combination of numerical simulation and experimental verification
Summary
E hydraulic loss and the pressure coefficient were normalized with respect to its value calculated with Grid 1(grid number 2.3 million), where Δhrepresents the hydraulic loss of the inlet passage. An average static pressure outlet boundary condition was applied with 1 atm at the water body outlet, and the mass flow rate was adopted as the outlet boundary of the inlet passage. E different mass flow rate at the outlet of the inlet passage was set by changing the inlet velocity ratio IVR. IVR refers to the ratio of the ship speed to the averaged axial outflow velocity at the passage outlet. E averaged axial outflow velocity at the passage outlet is an important parameter to describe the flow phenomena in the inlet, where the speed is changed from the ship speed to the pump velocity. Where vpassage is the averaged axial outflow velocity at the passage outlet (in m/s) and vs is the ship speed (in m/s)
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