Aiming at the difference in the cavitation sensitivity of the control valve at different measuring points of the regulating valve body, study on the difference of cavitation induced vibration and the cavitation sensitivity of different measuring points was carried out. A test platform for cavitation-induced vibration acceleration signal acquisition of regulating valve was built, and the acceleration signals of cavitation vibration of regulating valve at multiple measuring points were simultaneously collected. Two characterization parameters, the acceleration level ratio and the gravity frequency, were proposed. Frequency spectrum of the cavitation vibration signal of regulating valve was divided by the 1/3 octave frequency spectrum, and finally the frequency band most sensitive and location of measuring points to cavitation development was obtained. Results show that the vibration signals of measuring point on the same surface of the regulating valve body are similar, and the signals on different surface are significantly different. Vibration signals of the regulating valve are anisotropic. Development of cavitation extent mainly causes the vibration intensity of the frequency band above the center frequency of 10000 Hz to increase. It is suitable for monitoring cavitation state of control valve.

The flow state in the flow channel of the control valve directly affects its service life and system stability. In order to explore the three-dimensional flow field information inside the control valve, a series of three-dimensional grid nodes were obtained by shooting different planes with a two-dimensional particle image velocimetry (2D-PIV) device, and the flow field information of unknown nodes was obtained by interpolation, so as to realize the three-dimensional reconstruction of the control valve flow field. The experimental results show that the overall trend of the three-dimensional reconstructed velocity field is consistent with that of the two-dimensional velocity field. The oil at the throttle port of the control valve forms a counter jet due to the throttling effect, and the jet converges to form a high-speed overall jet in the downstream of the valve core head. The combination of impinging jets on both sides in the top area of the valve core will produce a certain amount of oil backflow. The overall flow channel velocity decreases gradually with the moving out of the shooting plane. The velocity distribution of the upstream flow channel decreases steadily at first and then maintains a stable value. The velocity value near the throttle orifice increases first and then decreases, with a large variation. The wall resistance and shear force keep the near-wall velocity stable. The flow velocity in the downstream region is concentric and the flow field changes from turbulent flow to orderly flow. The simulation results show that the overall area of the three-dimensional reconstruction flow field is primarily consistent with the theoretical flow field. The maximum reconstruction error is 9.5%, occurring in the high-speed flow area of the throttle. The experimental reconstruction results is highly similar to the simulation reconstruction results and the reconstruction effect in the smooth flow area is better than that in the violent part. The research can provide a reference for the structural optimization design of the control valve and the improvement of cavitation performance, and is also provides an effective reference for the three-dimensional flow field measurement of the micro-channel.

In order to reveal the influence factors of regulating valve’s service life in coal liquefaction, and ensure the safety and stability of coal liquefaction system operation, numerical simulations were carried out based on turbulence model, cavitation model and discrete phase model to address the complex multiphase flow problem of gas liquid solid. In the investigation, the distribution characteristics of erosion wear and cavitation inside the valve were studied, and the coupled damage rate of cavitation erosion in key parts of the valve core was obtained. Then, the coupled cavitation erosion wear behavior of solid multiphase flow in the flow channel during the operation of the regulating valve was reproduced through experiments, and the damage morphology of the metal tin valve core under continuous cavitation erosion composite action was analyzed. Finally, the damage degree of tin valve cores under different working conditions was quantitatively evaluated using roughness values, and the impact fatigue and composite damage mechanism of valve core surfaces were explored. The results show that the main area where cavitation occurs in the coal liquefaction regulating valve is from the throttle port to the head of the valve core. The range of cavitation increases with the increase of inlet pressure, and the cavitation intensity also increases accordingly. Under different import pressures, the extreme value of the surface erosion rate of the valve core appears at the head of the valve core, with a maximum erosion wear rate of 1. 42 × 10^-4 kg/(m²·s), which is more than 10 times that of other erosion areas. The reason is that the high-speed fluid backflow at the head of the valve core carries particles and impacts the head of the valve core, while the collapse of bubbles impacts the surface of the valve core. In addition, it is also found that the surface of the regulating valve core, which works for a long time under the coupling effect of erosion and cavitation, exhibits characteristic morphology such as grooves and corrosion points.