Aerodynamic Admittances Of Airfoil And Rectangular Cylinder

The research history of the aerodynamic admittance has been reviewed,the status and the progress of the research on the aerodynamic admittance have been summarized,the shortcomings in the current research have been pointed out.Combining the theoretical analysis and the experimental research,the aerodynamic admittances of the airfoil and the rectangular cross-section are studied in detail.The main contents of the paper are as follows:1.The research history of the buffeting force and the aerodynamic admittance of the airfoil are reviewed.The status and progresses of the research on the aerodynamic admittance of rectangular cross-section are summarized.The characteristics of the one-wavenumber aerodynamic admittance,the two-wavenumber aerodynamic admittance as well as the three-dimensional aerodynamic admittance are concluded.2.The buffeting force on an infinite wing in turbulent flow is described based on the three-dimensional theory.A general form of the spanwise coherence function of the buffeting force is derived.The parameters that control the importance of the three-dimensional effects are investigated.The role of the ratio of the turbulence integral scale to the width and the ratio of the spanwise length to the width in the calculation of the buffeting force are analyzed.This expands the conditions for the strip assumption to apply.A direct measurement approach of the one-wavenumber aerodynamic admittance in turbulent flow is presented.The validity of the strip assumption used in the buffeting analysis of the line-likestructure is verified.By introducing the empirical model of the correction term of the aerodynamic admittance,the three-dimensional buffeting force analysis is generalized to the bluff body.3.By the use of the pressure measurement,the aerodynamic admittances of a NACA 0015 airfoil and rectangular cross-sections of five different width to depth ratios are measured in homogeneous turbulence generated by grids and spires.The characteristics of the surface pressure distribution on these models are analyzed.Using the general form of the spanwise coherence function of the buffeting force,the aerodynamic admittance correction terms of the airfoil and the rectangular cross-section are determined.The one-wavenumber aerodynamic admittances of the NACA 0015 airfoil and the rectangular cross-section are identified.The empirical formula for the one-wavenumber aerodynamic admittance of the rectangular cross-section is proposed.4.By the use of the force measurement,the aerodynamic admittances of the NACA 0015 airfoil with three different aspect-ratios and the 5:1 rectangular cross-section with one aspect-ratio are measured.The validity of the direct measurement approach of the one-wavenumber aerodynamic admittance in turbulent flow is verified.The consistency between the force measurement and the pressure measurement is discussed.