Investigation Of Mechanism Of Widened Steady Working Range For Skewed-swept Rotating Blades

ABSTRACTIn this presellt paPer, the aerodynandc and aeroacoustic calculation offlow field in conventional (radial) rotor blades and skewed-swept rotorblades has been carried out, in order to find out the mechanism of widenedsteady working range of axial fans with skewed-swept rotor blades. Therotor blades are equipped with the same geometrical parameters except thechord length and the gravity centre line airfoils. Through the computedresult, the aPplication of skewed-swept rotor b1ades changes the radialpressure gradient, Which is an influence on the flow region. As a result, itchanges the distribution of the aerothermodyndric parameters.Compared the calculating results with the testing results, it is found thatthey agrees with each other very well, including rotor efficiency, pressurerise, outlet angle of floW loss and average ratio of pressure. This showsthe choice of numerical model is propef, which can lead to the reliablesimulation of flow field in rotor blades. The mechanism of widened stallmargin has been pointed out on the basis of the aerodroamic calculationsin the steady working condition.It analyzes 3D flows in the radial and skewed-swept blade cascades,using 3D Reynolds-averaged Navier-Stokes equations. Througl1 thethorough analysis of several kinds of widely used high resolution schemes,high accurate NND scheme is chosen in the end. It aPpIies anunconditional stable imPlicit algorithm (LU-SGS) to solve the equations,which imProves the converging rate to the calculations of turbomachineryturbulent flow. Therefore, the acctiracy and comPutationa1 efficiencyhave achieved remarkable improvements for the complex and time-consuming problem in the numerical simulation of three dimensionalviscous flows in skewed-swept rotor blades. Furthef, the radical force has- II -been modified in this paper.The design is caffied out for the radical and skewed-swept rotor blades, choosing reasonable main parameters and then working out the structure of rotor blades by means of aerodynamic calculation using the theory of isolated airfoils. Moreover, it is discussed with emphasis on proper selection of the skewed-swept angle and baselines of the airfoil gravity centre. Eventually considering the match between rotor blades and static ones, the further aerodynamic-aeroacoustic optimum design is discussed.