| Hydraulic media plays an extremely important role in hydraulic systems.However,mineral-based hydraulic oil is highly flammable,and it is difficult to avoid leaks in hydraulic systems,which can pollute the environment and endanger personal safety.With the increasing consumption of petroleum resources and resource shortages,water-based media is gradually replacing mineral-based hydraulic oil in some special fields with high safety requirements,such as metallurgy and mining,and gradually moving from special application areas to general engineering fields due to its safety and environmental advantages.However,pure water-based media has low viscosity and poor lubricating performance,which can aggravate the wear of key friction pairs in the hydraulic system,leading to a decrease in system efficiency.Gear pumps,as the power source of hydraulic systems,have been widely used due to their simple structure,strong self-priming performance,and insensitivity to media pollution.With the increasingly prominent issues of resource shortages and sustainable development,the influence of new hydraulic media on the volumetric efficiency of gear pumps has been studied.Firstly,the classification of hydraulic media is elaborated.The current research status of water-based nanofluid viscosity and anti-wear and friction reduction is outlined,and its feasibility as a hydraulic medium in hydraulic systems is analyzed.The research status of volumetric efficiency of gear pumps is briefly described,and the influencing factors of volumetric efficiency of external meshing gear pumps are analyzed.In combination with corresponding fluid theories,the correlation between the volumetric efficiency of external meshing gear pumps and the working pressure and frictional wear condition is examined.The influencing factors of the volumetric efficiency of gear pumps were studied,and the effects of the pump’s own structure,hydraulic media physical properties,outlet pressure,and key frictional wear on the volumetric efficiency of the pump were analyzed.The CFD simulation technology was adopted to monitor the instantaneous flow rate of water-based nanofluid and pure water gear pumps at the outlet under different outlet pressures,and the effects of outlet pressure and hydraulic media physical properties on the instantaneous flow rate of the pump were analyzed.The simulation results showed that the volumetric efficiency of the gear pump decreased with the increase of working pressure.At the same working pressure,the higher viscosity of water-based nanofluid compared to pure water made the volumetric efficiency of water-based nanofluid gear pump higher than that of pure water gear pump under the same conditions.The wear mechanism of water-based nanofluid was analyzed,and the wear test was designed to study the anti-wear performance of water-based nanoscale SiC fluid hydraulic media using wear volume as the characterization parameter.Design the wear test and volumetric efficiency test of the gear pump Compared with pure water,the wear amount of gear pump using water-based nanoscale SiC fluid hydraulic medium is smaller.The excellent anti-wear performance of water-based nanofluid effectively reduces the wear of key friction pairs,reduces the growth rate of gaps caused by wear,lowers the speed of volumetric efficiency decrease,and extends the wear life of the pump.However,when the mass fraction of nanoscale SiC particles increased to a certain value,the wear amount of the gear pump remained almost unchanged or even decreased,because the nanoscale particles reduced the wear amount by depositing on the surface of the friction pair.The volumetric efficiency of the gear pump decreased with the increase of working pressure,while the viscosity of the hydraulic medium increased with the increase of mass fraction of nanoscale SiC particles,resulting in higher volumetric efficiency under the same working pressure.Compared with pure water,water-based nanoscale SiC fluid has stronger carrying capacity,which enables the gear pump to maintain higher volumetric efficiency for a long time under higher working pressure. |
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