Study On Unsteady Flow In Scroll Compressor And Deformation Of Orbiting Scroll

As a newer generation positive-displacement compresssor,scroll compressor which is widely used in refrigeration,air compression and gas transportation has some advantages like: high efficiency,low level of noise and vibration,high reliability.A calculational fluid dynamics(CFD)model including a whole dynamic working process and numerical simulation method including moving boundary,grid skewness and small leakage gap has been biult to reveal the overall flow state distribution and the rules of flow field distribiutions.A leakage model is proposed to solve a problem that the quality of the mesh in the gap will decreased after remeshing.A CFD model considering friction viscosity and properties of real gas is built based on the geometry characteristics of radial leakage and flank leakage to study the pressure and velocity distribution.A method to test trasient pressure on 6 designated spot in the working chamber of R410 a compressor is studied and errors analysis is proceed based on test and simuation data.The prediciton accurance of the transient pressure distribution on monitoring points is verified.A nolve scroll wrap is obtained with a taperd gap width and thickness.Further more with an arc-arc discharge geometry,the volumtric effiency improved.The new scroll wrap can be used in oil flooded or liquid injection scroll compressor to solve a problem of liquid slugging.Loading the transient pressure which is obtained from a Large Eddy Simulation turbulant model as a boundary condition of orbiting scroll solid,the stress and deformation rules can be gained at any orbiting angle.Some differeces between two kinds of scroll wraps in formation,flow field distribution and deformation were compared and the advantages of a novel kind of wrap were verified.The results obtained based on real boudary condition show that,pressure is equally distribued in the chamber and the maximum and minimum pressure difference is less than 5% but unequally along the axis which has a pressure fluctuation.The pressure differences between the inner and outer scroll wrap decrease with the involute angle.Compared with test data,some errors arises in simulation data: the pressure in sunction chamber is steady,the average relative errors is 1.4%.The flow state in compression chamber is complex,the average relative errors is 7.4%.In discharge chamber,the average relative errors is 2.3%.The velocity distribution is unequal with a maximum and minimum velocity difference of 180m/s in a single chamber.Pressure changed gradully and the maximum velocity is 200m/s in the leakage gap.Compared with current model,the mass flow rate curve with pressure match well,but the rate of decreasing is faster because of the simple algorithm based on correction of pressure.The maximum stress occures in the root of the scroll and the deformation in the top the the scroll.The stress distributions concentrate on a 500°involute angle.Two obvious deformations occur on a 465° and 262° involute angle.The CFD method to calculate and verify the flow inside the working chamber is helpful to reveal the rulse that how the pressure distribution affect the stress and deformation of scroll solid.The reserach method in this project can be used in other project related to positive displacement machinery and open a new area for fluid and structure interaction.