Hydraulic devices play an essential role in mechanical engineering due to their high-power density,good controllability,flexible application and high robustness,which expose innovative methods of energy transmission.H...Hydraulic devices play an essential role in mechanical engineering due to their high-power density,good controllability,flexible application and high robustness,which expose innovative methods of energy transmission.However,in applications where there is an increased risk of fire or explosion,the commonly used combustible mineral oils represent an unacceptable safety hazard.In such cases,fire-resistant,water-based hydraulic fluids are in demand.A special feature of these liquids is their high cavitation tendency and the associated strong erosion wear.The aim of this research is to predict the cavitation behaviour of HFC and the subsequent erosion phenomena using numerical methods and to validate the results with experiments.Additionally,experimental results for HFC were compared with flammable mineral oils(e.g.HLP).The findings help to implement further developments to decrease the erosive effect of cavitation in high-pressure differences in hydraulic components.For this purpose,flow geometries of typical hydraulic components,e.g.valve and pump,are used for experimental and numerical investigation.The large-eddy simulation(LES)turbulent modelling is used with Zwart-Gerber cavitation model.The cavitation aggressiveness is quantified by cavitation erosion indices according to Nohmi.展开更多
The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step...The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step and harmonic response and a stability criterion using elementary operations only. It also mathematically proves the intrinsic connection between the gradient of the static p-Q-characteristic and the stability. Thus, the new method offers four main advantages.展开更多
文摘Hydraulic devices play an essential role in mechanical engineering due to their high-power density,good controllability,flexible application and high robustness,which expose innovative methods of energy transmission.However,in applications where there is an increased risk of fire or explosion,the commonly used combustible mineral oils represent an unacceptable safety hazard.In such cases,fire-resistant,water-based hydraulic fluids are in demand.A special feature of these liquids is their high cavitation tendency and the associated strong erosion wear.The aim of this research is to predict the cavitation behaviour of HFC and the subsequent erosion phenomena using numerical methods and to validate the results with experiments.Additionally,experimental results for HFC were compared with flammable mineral oils(e.g.HLP).The findings help to implement further developments to decrease the erosive effect of cavitation in high-pressure differences in hydraulic components.For this purpose,flow geometries of typical hydraulic components,e.g.valve and pump,are used for experimental and numerical investigation.The large-eddy simulation(LES)turbulent modelling is used with Zwart-Gerber cavitation model.The cavitation aggressiveness is quantified by cavitation erosion indices according to Nohmi.
文摘The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step and harmonic response and a stability criterion using elementary operations only. It also mathematically proves the intrinsic connection between the gradient of the static p-Q-characteristic and the stability. Thus, the new method offers four main advantages.
