Toward Improved Rotor-Only Axial Fans—Part I: A Numerically Efficient Aerodynamic Model for Arbitrary Vortex Flow

Abstract

A numerically efficient mathematical model for the aerodynamics of rotor-only axial fans has been developed. The model is based on a blade-element principle whereby the rotor is divided into a number of annular streamtubes. For each of these streamtubes relations for velocity, pressure, and radial position are derived from the incompressible conservation laws for mass, tangential momentum, and energy. The resulting system of equations is nonlinear and, due to mass conservation and pressure equilibrium far downstream of the rotor, strongly coupled. The equations are solved using the Newton-Raphson method, and solutions converged to machine accuracy are found at small computing costs. Calculations are found to agree well with published measurements. [S0098-2202(00)01502-9]