Energy-Based Drag Breakdown in Compressible Flow by Wake-Plane Integrals

摘要

A series of far-field methods based on the momentum balance have been developed recently to predict and decompose the aerodynamic drag in the steady flow past a body. In this work, a far-field approach based on the energy equation is developed to study the aerodynamic drag in compressible flows. A new drag formula expressed solely by a wake-plane integral is derived. The Reynolds-averaged Navier-Stokes equation is solved for flows past the RAE 2822 airfoil and the ONERA M6 wing. Numerical results confirm the accuracy of the present drag formula, and they show that the integrand is compact and positive almost everywhere in the wake. Using the concept of exergy, the drag is further decomposed to a reversible component, an irreversible component, and a minor component related to the viscosity and heat conduction on the wake plane. The behavior of each drag component is discussed.