Trailing-vortex drag coefficient in shock-free attached flow - cambered and twisted wings
Abstract:ESDU 10022 provides a means of predicting the trailing-vortex drag coefficient, CDV, of wings with or without camber and twist, at a given value of in CL shock-free attached flow. Equations and graphs are provided for predicting the trailing-vortex drag coefficient of wings with quarter-chord sweep angles not exceeding 45°, aspect ratios not exceeding 12, and linear or simple non-linear spanwise twist variations of up to 10° wash-in or wash-out. ESDU 10022 is applicable to both straight-tapered and cranked wing planforms where the section geometry, including camber, either remains unaltered or varies with spanwise location.
The method is based on a theoretical analysis using inviscid spanwise loading distributions generated by the Multhopp-Richardson lifting-surface method, obtained from ESDU 95010. As a result the trailing-vortex drag coefficient obtained by the method is the inviscid component of the total wing drag coefficient in shock-free attached flow. The viscous drag coefficient, which is predicted using ESDU 07002, is the component of the total drag coefficient arising from all viscous effects. Therefore, ESDU 07002 can be used in conjunction with the method of ESDU 10022 to predict the total wing drag coefficient at a given value of CL in a shock-free flow.
Trailing-vortex drag coefficient data obtained using the Full Potential (FP) program and a post processing program, both contained in ESDU 06016, are compared with data obtained using the method of ESDU 10022. There is good agreement between the two sets of data.
Three worked examples illustrate the use of the method.
|Data Item ESDU 10022|