The paper employs the method of characteristics to solve the transient flow control equations of pipelines, verifies the accuracy of the numerical method using data from existing literature, and establishes a simple pumping station water supply system. It investigates the detection of blockages and leaks in the pipelines of the system while considering variations in pipe elevation and pump boundary conditions. It is found that pressure waves generated by rapid closure of end valves reflect when they reach the locations of blockages and leaks. The reflected pressure waves back to the valve cause abrupt changes in pressure signals, and different types of faults result in different forms of abrupt changes. Based on the time of the abrupt change and the wave speed of the pipeline, the locations of blockages and leaks can be calculated. The final research results confirm that the method demonstrates high precision in locating blockages and leaks across different parameters, with detection errors below 1% under ideal conditions. Moreover, it effectively identifies blockages and leaks at points of pipe elevation changes and pipe connections. Importantly, it displays strong applicability even in scenarios where both blockages and leaks coexist within the system.

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Cavitation and particle erosion are critical factors affecting the performance and durability of hydraulic machinery. This study employs a combined numerical simulation approach by integrating a cavitation model with a Discrete Phase Model (DPM) erosion model. It examines single erosion and cavitation-erosion synergy under varying cavitation inducer angles. The results show that intensified vorticity behind the inducer increases particle concentration and sliding erosion, leading to higher erosion rates and larger erosion areas compared to the single erosion model. Additionally, a direct correlation is established between cavitation occurrences, particle velocity, vorticity, and erosion rates at different rotational speeds. Comparative analysis with experimental data indicates an 11.52% improvement in predictive accuracy for wear using the cavitation-erosion synergy model. These findings provide valuable insights for predicting wear in hydraulic machinery under cavitation and particle erosion conditions, contributing to enhanced equipment reliability and extended service life.

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The patterns and characteristics of blood flow in the heart are the basis of exploring the mechanism of abnormal blood physiological parameters and pathological changes of heart tissue structure. In this paper, the left ventricular model was reconstructed and optimized based on Computed Tomography (CT) scan data. Combined with the motion characteristics of the myocardium wall, the mathematical model of the left ventricle geometric model was established, and the effect of mitral stenosis on the blood flow of the left ventricle was studied by using the dynamic grid technique. The hydraulic radius was used to represent the stenosis degree of mitral valve stenosis. It was found that the velocity and pressure at the inlet increased during systolic period, and the shear stress increased when the inlet area decreased. The velocity and pressure increase first and then decrease in diastolic period. When the hydraulic radius is small, the overall shear stress in the left ventricle is large, reaching a maximum of 4.60 Pa at 6/8T. In this paper, the simulation of the heart through dynamic simulation provides important reference value for the subsequent research on the heart.

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In order to analyze the flow characteristics of the internal flow field in the draft tube of the Francis turbine and reveal the coherent structure evolution, the flow in Francis-99 model turbine are simulated under three working conditions. The three-dimensional coherent structure and dynamic information of single fluctuation frequency in the draft tube under different working conditions are extracted based on numerical computation by dynamic mode decomposition (DMD) method. The averaged flow field (mode 0) occupy the most flow field energy (>96%), and the first 6th modes occupy more than 99.5% flow field energy, representing the dominant flow structure in draft tube. The spatial coherent structures of mode 1 to mode 6 show multiple spiral vortex ropes surrounding the center vortex rope of mode 0 coherent structure, and the number of the vortex ropes equal to mode number. The temporal evolutions of unsteady flow structures of modes with nonzero frequency repeat the cycle that, generating from the draft tube inlet, growing to entire flow passage downward, disappearing slowly and arising again.

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To clarify the effect of the double-suction pump suction chamber rib and its installation on the induced noise of the pump, suction chamber models with different rib positions are designed. The RANS method and the standard k-ε turbulence model are used to simulate the internal flow in the pump and the direct boundary element method is applied to numerically calculate the flow-induced noise sound field in the pump. The results show that the pressure pulsation amplitude in the main frequency of the pump has been reduced after the installation of the rib, and the largest decrease is at the seventh section of the volute under the central rib scheme, up to 53.2%. The high sound pressure areas of the suction chamber, impeller, and volute are mainly distributed at their outlets. After the installation of suction chamber rib, the range of high sound pressure areas and maximum sound pressure values in these flow-passing components are reduced. The main frequency of flow induced noise under each scheme appears at one time the blade passing frequency. The sound pressure reduced most at the inlet of the suction chamber due to the influence of the rib, with the largest reduction of 8.49% in center rib scheme. The research results can provide a theoretical reference for optimizing the noise characteristics of double suction pump.

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Gravitational vortex type water turbines mainly consist of a tank and a runner, and are applicable to low head and small flow rates. In this study, a one-dimensional design method is proposed to establish a hydraulic design method for this type of turbine, in which the flow in the tank is assumed to be a free vortex, and the shapes of the volute tank and runner are determined from the given specifications. In this design method, other runner parameters vary greatly depending on the value of runner outer diameter. Based on this design method, three types of water turbines with different runner diameters were designed, and their performance and flow fields were investigated by free surface flow analysis and through experiments. As a result, the water turbine with the largest runner outer diameter had the lowest tank outlet loss and tank loss, resulting in a slightly smaller calculated effective head than the design value, but the calculated values of the flow at the blade inlet and outlet were relatively close to the design value. Therefore, the water turbine with the largest runner outer diameter demonstrated the highest theoretical head, the highest turbine output, and the highest turbine efficiency.

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