The radial gap between the impeller tips and volute tongue is an important factor influencing the overall performance and unsteady pressure fields of the pump as turbine (PAT). In this paper, a numerical investigation of the PAT's steady performance with different radial gaps was first performed. The results show that there is an optimal radial gap for a PAT to achieve its highest efficiency. An analysis of the PAT's unsteady pressure fields indicates that the rotorstator interaction of a rotating impeller and stationery volute would cause high frequency unsteady pulsation within the volute and low frequency unsteady pressure pulsation within the impeller. The high frequency unsteady pressure pulsation would propagate through the PAT's flow channel. Thus, the unsteady pressure field within the impeller is the combined effect of these two kinds of pressure pulsations. The unsteady pressure pulsation within the outlet pipe is mainly caused by the propagation of unsteady pressure formed within the volute. With the increase of the radial gap, the amplitude of high frequency unsteady pressure pulsation within the volute caused by the rotor-stator interaction is decreased, while the amplitude of the low frequency unsteady pressure pulsation caused by the rotor-stator interaction within the impeller remains unchanged.

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Due to the special structure characteristics, the switching process control from pure electrical driving mode to compound driving mode of the single-shaft parallel hybrid powertrain has caught broad attentions from related researches. In this study, a novel mode transition control method based on model predictive control algorithm is proposed to regulate the starting and engaging processes into driveline of the engine via an automatic clutch. According to the system states evolution process, the system control commands, that is, the immediate output torques of the engine, the motor, and the clutch during the mode transition process, are determined online by the proposed model predictive control controller, which derives the optimal control sequences to minimize the defined objective function by adopting quadratic programming in the prediction horizon. To better demonstrate the efficacy of the proposed control method, a simulation analysis platform is built based on MATLAB/Simulink and AVL/Cruise. Simulation results show that the coordinated control method can effectively suppress the vehicle longitudinal jerk within the reasonable range and reduce the clutch wear loss during the mode transition process.

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In order to meet the requirement of coal mine flooding emergency rescue, a high-power, high-head, and small-volume high-speed wet submersible pump has been designed. This article provides comparison and analysis for nine combination cases of different matching laws between the impeller blade number Z 1 (Z 1 = 5, 6, 7) and the diffuser vane blade number Z 2 (Z 2 = 8, 9, 10). The comparison of the pump performance and inner flow characters, such as the head, efficiency, radial force, and pressure pulsation coefficient, at different blade number matching of impeller and diffuser has been studied by the computational fluid dynamics software CFX. These are solved through the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with the shear-stress transport k-v turbulence model. Furthermore, the computational fluid dynamics method is validated by experimental data collected in the laboratory. The results show that the combination of blade number of impeller and diffuser vane has a significant effect on the behavior. The steady analysis of combinations indicates that an increased efficiency occurs along with the reduced blade number. From the unsteady perspective, the 7 + 8 (Z 1 = 7, Z 2 = 8) case has the lowest fluctuation and relatively small radial force. In conclusion, the above results can provide reference for choosing blade numbers matching law between impeller and diffuser vane of the high-speed rescue pump.

In this article, three types of high-speed mine submersible pumps were designed and experimented. During the reliability performance test, the axial thrust balancing device of GFQ150-700 was overloaded and damaged due to an unsuitable designed value of axial thrust. The designed hydraulic axial thrust with the actual value is compared in this article, and the reason for axial thrust deviation is discussed. Results show that axial thrust of the theoretical calculation is close to the numerical simulation value at a certain extent.