Normal Reflection Characteristics of One-Dimensional Unsteady Flow Shock Waves on Rigid Walls from Pulse Discharge in Water

Abstract

Strong shock waves can be generated by pulse discharge in water, and the characteristics due to the shock wave normal reflection from rigid walls have important significance to many fields, such as industrial production and defense construction. This paper investigates the effects of hydrostatic pressures and perturbation of wave source (i.e., charging voltage) on normal reflection of one-dimensional unsteady flow shock waves. Basic properties of the incidence and reflection waves were analyzed theoretically and experimentally to identify the reflection mechanisms and hence the influencing factors and characteristics. The results indicated that increased perturbation (i.e., charging voltage) leads to increased peak pressure and velocity of the reflected shock wave, whereas increased hydrostatic pressure obviously inhibited superposition of the reflection waves close to the rigid wall. The perturbation of wave source influence on the reflected wave was much lower than that on the incident wave, while the hydrostatic pressure obviously affected both incident and reflection waves. The reflection wave from the rigid wall in water exhibited the characteristics of a weak shock wave, and with increased hydrostatic pressure, these weak shock wave characteristics became more obvious.

Numerical Analysis on the Unsteady Radial Load on the Shaft of a Large-Scale Dredge Pump Unit

“…Dredge pumps are usually centrifugal pumps. There are two main causes of rotor vibration and shaft fatigue in centrifugal pump units: 1) the eccentric mass of a rotor due to poor machining quality or uneven wear leads to rotor imbalance during operations (Tan et al 2021;Lu et al 2022), and 2) the fluid excitation force exerted on the impeller has obvious unsteady characteristics due to rotor-stator interaction, especially in high-capacity pumps (Jia 2017;Yan 2017;Cui et al 2020;Zhu 2021). One component of the fluid excitation force, the hydraulic radial force, whose magnitude and direction usually vary with time, is a major cause of pump vibration.…”