Ball valve is an important control component in the pipeline transportation system. It is widely used in pipeline transportation systems to control the pressure and flow parameters of the conveying medium. Based on the user-defined UDF technology and the standard k-$\epsilon$ turbulence model using computational fluid dynamics techniques, the transient numerical simulation of the internal flow field of the ball valve under the variable speed law and different opening degrees is carried out, and the flow coefficient characteristics, resistance coefficient characteristics, inlet and outlet pressure drop, and internal flow field distribution of the ball valve are analyzed and studied. The results show that by designing the curve function of the ball valve actuator movement process with different structure forms, different types of ball valve flow coefficient and resistance coefficient curve can be obtained, which makes the ball valve as a flow regulating valve more widely used; Modifying the motion law of ball valve electric actuator has little influence on the distribution of ball valve flow field. As long as the motion law of ball valve actuator is optimized within a reasonable range, the purpose of pipeline flow control can be achieved, the inconvenience of valve replacement can be reduced, and the economic cost can be saved.

Supersonic impinging jet flows always occur when aircrafts start short takeoff and vertical landing from the ground. Supersonic flows with residues produced by chemical reaction of fuel mixture have the potential of reducing aircraft performance and landing ground. The adverse flow conditions such as impinging force, high noise spectrum, and high shear stress always take place. Due to rare data on particle-gas impinging jet flows to date, three-dimensional numerical simulations were carried out to investigate supersonic impinging jet flows of particle-gas two phases in the present studies. A convergent sonic nozzle and a convergent-divergent supersonic nozzle were used to induce supersonic impinging jet flows. Discrete phase model (DPM), where interaction with continuous phase and two-way turbulence coupling model were considered, was used to simulate particle-gas flows. Effects of different particle diameter and Stokes number were investigated. Particle mass loading of 10% were considered for all simulations. Gas and particle velocity contours, wall shear stress, and impinging force on the ground surface were obtained to describe different phenomena inside impinging and wall jet flows of single gas phase and gas-particle two phases.

Francis turbine is a core energy conversion part and low frequency vibrations caused by unsteady vortex rope in the draft tube may damage the unit through resonance. Therefore, a more comprehensive assessment and monitoring of the status of Francis turbine is of great significance for unit stability. In this hydraulic machinery, mechanical impulses and hydraulic excitation are co-existing. The former manifests as a narrow low frequency band with high kurtosis, while the latter represents a wide high frequency band with energy associated with the vortex rope. Based on that, a novel method coined Convkurgram is proposed to suppress the extreme high kurtosis mechanical components and extract the hydraulic carrier wave efficiently. Besides, it takes multiple information frequency bands into consideration in case of contamination waves exist. Finally, the method is evaluated by means of actual vibration signals collected from the hydroelectric generating unit under normal and cavitation conditions. The results show the proposed method recognizes the characteristic frequency bands of mechanical components and hydraulic carriers as well as extracts the shaft frequency and blade passing frequency successfully.