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
Measures of individualisation and integration offer a great potential for further development and optimisation in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. To ...Measures of individualisation and integration offer a great potential for further development and optimisation in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. To exploit these benefits the independent metering technology appears to be very attractive which motivates the extensive research on this topic during the last decade. This article starts with a brief overview on common hardware arrangements and general control approaches. Furthermore an approach to the safety evaluation of novel independent metering systems is given. Afterwards different application examples are presented, such as a cardboard packaging press in the area of stationary machines and in the fields of mobile machines a working implement of an excavator and an active steering system for tractors. The article ends with a brief summary of the valve requirements for independent metering.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Measures of individualisation and integration offer a great potential for further development and optimisation in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. To exploit these benefits the independent metering technology appears to be very attractive which motivates the extensive research on this topic during the last decade. This article starts with a brief overview on common hardware arrangements and general control approaches. Furthermore an approach to the safety evaluation of novel independent metering systems is given. Afterwards different application examples are presented, such as a cardboard packaging press in the area of stationary machines and in the fields of mobile machines a working implement of an excavator and an active steering system for tractors. The article ends with a brief summary of the valve requirements for independent metering.
