Abstract:

ESDU 01033 is the sixth in a sequence to accompany the VGK method for two-dimensional aerofoil sections. VGK is a CFD (computational fluid dynamics) method coded in Fortran for predicting the aerodynamic characteristics of a two-dimensional aerofoil in a subsonic freestream, including the effects of viscosity (boundary layers and wake) and shock waves. VGK uses an iterative approach to solve coupled finite-difference equations for the inviscid flow region (assumed to be potential) and the viscous flow region (represented by integral equations). It was developed over a period of years at RAE/DERA (now QinetiQ) Farnborough, and is made available by ESDU under the terms of an agreement with QinetiQ.

ESDU 01033 extends the VGK method to deal with an aerofoil with simple hinged flaps. These may be either leading- or trailing-edge flaps, or both types may be present together. The method is restricted to small deflections of effectively sealed flaps, since there is no modelling of any flow through a gap between a flap and the main aerofoil element, nor are the details of the flow near any irregularity in the surface contour produced by flap deflection represented.

Procedures (and associated programs) for generating the surface coordinates of an aerofoil with deflected flaps are described, with deflection being represented either by rotation or by shearing. In each case smoothing may be applied to the regions where a flap and main aerofoil element meet. The additional functions incorporated in the flow program (VGKSF) in order to deal with a flapped aerofoil are presented. Use of the programs is described in detail and covers the calculation of aerodynamic characteristics (including hinge-moment coefficient) for a series of flap deflection angles.

A number of comparisons of VGKSF calculations with other results are presented, followed by an assessment of the accuracy of VGKSF predictions of aerodynamic characteristics.

See also:

• ESDU 96028: VGK method for two-dimensional aerofoil sections. Part 1: Principles and results
• ESDU 96029: VGK method for two-dimensional aerofoil sections. Part 2: user manual
• ESDU 97030: VGK method for two-dimensional aerofoil sections. Part 3: estimation of a separation boundary in transonic flow
• ESDU 98031: VGK method for two-dimensional aerofoil sections. Part 4: estimation of excrescence drag at subsonic speeds
• ESDU 99032: VGK method for two-dimensional aerofoil sections. Part 5: design to a specified upper-surface pressure distribution
• ESDU 03015: Transonic data memorandum. VGK method for two-dimensional aerofoil sections. Part 7: VGK for Windows