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.

A model of the pumping station lateral inflow forebay was established to explore the influence of different lateral bending angles of the pumping station lateral inflow. The lateral bending angles were set at 45° and 60°, and the two schemes were calculated separately. Analyzing the results of the numerical simulation showed that the flow patterns of the diversion passages of different schemes were good, but the advancing mainstream of the 1# inlet passage near the sidewall was seriously deviated after entering the forebay. Most of the water can flow smoothly into the inlet passage, while a small part of the water flowed into the sidewall and formed a backflow, resulting in a large-scale backflow zone near the left sidewall of the forebay. Moreover, the flow in the backflow zone was turbulent, which affected the water inlet conditions of the 1# water flow passage. Comparing the water inlet conditions of the water passage with the numerical simulation results of 45° and 60° bending angles showed that the larger the lateral bending angle of the forebay was, the worse the flow pattern of the water flow, and the more unfavorable the pump operation.

The layout of the pump station is easily affected by topography, site, and other factors, resulting in poor inlet flow patterns in the forebay, which seriously affect the normal operation of the pump station. To optimize its inlet flow pattern, the size of the hollow rectification sill has been continuously improved through physical model tests to meet the requirements of the required pump station inlet flow field. In this paper, particle swarm optimization (PSO) was combined with the Gaussian process (GP) to establish a particle swarm-Gaussian process (PSO-GP) model to predict the velocity uniformity of the inlet sump of pump stations with different hole-to-height ratios, hole-to-width ratios, upper-to-lower sill length ratios, and sill height-to-water table ratios. Finally, the hollow rectification sill with the optimal size was obtained and tested in the physical model to compare the rectification effect with other sizes of hollow sills. The results show that the algorithm model can help the traditional physical experiment quickly predict the velocity uniformity of the inlet sump of the pump station. Through the optimization by the PSO-GP algorithm, we can get the optimal size of the hollow rectification sill. Its hole-to-height ratio is 0.62, its hole-to-width ratio is 0.37, upper-to-lower sill length ratio is 0.63, and sill height-to-water table ratio is 0.23. It shows that this method is practical in the optimization design of the hollow rectification sill and provides a new method for the optimization of the flow field in the forebay of the pump station.

To explore the rectification parameters of the diversion piers optimized for the forebay of the pump station with a lateral angle of 45°, the orthogonal experiment and computational fluid dynamics methods are used to analyze the flow characteristics of the diversion piers under different parameter combinations. The flow pattern in the forebay of the side water inlet is improved. The rectification effect of the diversion piers under 16 schemes is analyzed, considering the length, width, radian, and relative height of the diversion piers. Combined with numerical simulation, a better rectification scheme is provided, and finally, a reasonable range of values for the rectification parameters of the forebay diversion pier of the side 45° bend angle pump station is obtained.