Jyoti Ranjan Majhi, Ranjan Ganguli¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 25-36, 2008, DOI:10.3970/cmes.2008.027.025

Abstract The flapping equation for a rotating rigid helicopter blade is typically derived by considering 1) small flap angle, 2) small induced angle of attack and 3) linear aerodynamics. However, the use of nonlinear aerodynamics can make the assumptions of small angles suspect. A general equation describing helicopter blade flap dynamics for large flap angle and large induced inflow angle of attack is derived in this paper with nonlinear aerodynamics . Numerical simulations are performed by solving the nonlinear flapping ordinary differential equation for steady state conditions and the validity of the small angle approximations are More >

M.H. Djavareshkian¹

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.4, pp. 329-342, 2005, DOI:10.3970/fdmp.2005.001.329

Abstract A pressure-based Euler scheme, based on a collocated grid arrangement is described. The newly developed algorithm has two new prominent features: (i) the use of normalized variables to bound the convective fluxes and (ii) the use of a high-resolution scheme in calculating interface density values to enhance the shock-capturing property of the algorithm. The algorithm is first tested for flows at different Mach numbers ranging from subsonic to supersonic on a bump in a channel geometry; then the results are compared with the corresponding ones obtained without the bounded scheme in the correction step. The More >

J. C. Páscoa¹, A. C. Mendes¹, L. M. C. Gato², R. Elder³

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 537-546, 2004, DOI:10.3970/cmes.2004.006.537

Abstract The paper presents an aerodynamic design method for turbomachinery cascades of blades. The prescribed conditions are the aerodynamic blade load and the blade thickness distributions. An iterative procedure was implemented, based on the solution of the Euler equations, to seek the blade geometry that provides the specified design conditions. A central finite-volume explicit time-marching scheme is used to solve the Euler equations in two-dimensional flow. The numerical scheme uses an adaptive nonlinear artificial dissipation term based on the limiter theory. Starting with the results from the flow analysis through an initially guessed cascade geometry, the More >

F. Simonetti¹, R. M. Ardito Marretta²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 81-90, 2000, DOI:10.3970/cmes.2000.001.383

Abstract Advanced propellers are being developed to improve the performance and fuel economy of future transport aircraft. To study them, various aerodynamic prediction models and systems (from theory to experiment) have been developed via several approaches (Free Wake Analysis, helicoidal source methods, scale model tests). This study focuses on the development of an efficient numerical method to predict the behaviour of rotor or propeller in forward flight. Based on a variational approach, the present numerical technique allows a significant reduction of computer resources used in the calculation of instantaneous velocities to determine the wake geometry and More >