Abstract
This study uses a combination of computational fluid dynamics (CFD) and experimental research to explore the influence of the length of the inlet duct on the hydraulic performance of the water jet propulsion pump device. By extending the oblique, straight, and long pipe section of the inlet duct, six sets of schemes were designed. The research results show that as the length of the inlet duct increases, the head, thrust, and inlet duct efficiency of the water jet propulsion pump first increase and then decrease, reaching the maximum value in scheme 4, but it has little effect on the efficiency of the entire water jet propulsion system. In addition, after extending the obliquely straight long pipe section of the inlet flow channel, the velocity distribution of the outlet section of the flow channel is gradually uniform, and the absolute value of the vorticity first increases and decreases, but the uniformity of the velocity distribution and the weighted average angle change little. This research enriches the research theory of the inlet duct and also provides a reference for the selection of inlet duct length and its performance optimization.
Highlights
Traditional propeller propulsion has high propulsion efficiency in low and medium speeds, and the propeller propulsion efficiency of displacement ships is about 65% [1], the water jet propulsion pump device has high efficiency and low noise when the ship is traveling at high speed, and it is widely used on high-speed ships [2]
In order to understand the influence of the length of the inlet duct on the external characteristics of the inlet duct, the uniformity of the outlet of the inlet duct, and the internal characteristics of the inlet duct, numerical simulation and qualitative and quantitative analyses will be carried out in this article. is is conducive to the application of the water jet propulsion pump device on ships and expands the theoretical analysis content of the inlet duct
It can be seen from the figure that the head decreases with the increase of the flow, and the efficiency increases with the increase of the flow. e experimental results of the water jet propulsion device and the overall trend of the numerical results are consistent, so the numerical simulation results in this article are credible
Summary
Traditional propeller propulsion has high propulsion efficiency in low and medium speeds, and the propeller propulsion efficiency of displacement ships is about 65% [1], the water jet propulsion pump device has high efficiency and low noise when the ship is traveling at high speed, and it is widely used on high-speed ships [2]. Cao et al [24] carried out numerical simulations on the water jet propulsion pump device and revealed the internal relationship between the unevenness of the internal flow of the inlet duct and the performance deviation of the water jet propulsion pump device and essentially studied the performance deviation between the uniform and nonuniform suction flow. Regarding the innovation of the research method of the inlet flow path, Huang and Luo [25] improved the NSGA-II and TOPSIS technologies and optimized the performance of the inlet flow channel with the unevenness and verticality of the outlet and hydraulic efficiency as the optimization goals. Predecessors have carried out a lot of research work on the inlet duct and the entire water jet propulsion pump device, but there are few aspects of the analysis and optimization of the inlet duct parameters. In order to understand the influence of the length of the inlet duct on the external characteristics of the inlet duct, the uniformity of the outlet of the inlet duct, and the internal characteristics of the inlet duct, numerical simulation and qualitative and quantitative analyses will be carried out in this article. is is conducive to the application of the water jet propulsion pump device on ships and expands the theoretical analysis content of the inlet duct
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