ESDU 96029:2010

INTRODUCTION

VGK is a CFD (computational fluid dynamics) method coded in
Fortran for predicting the aerodynamic characteristics of a
single-element 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).
The aerofoil boundary-layers must be attached for VGK to produce
results that correspond to the real flow, but the code has been
calibrated against experimental data to provide a method of
estimating a separation boundary* – see Ref. 2 and Part 3. VGK was
developed over a period of years at RAE/DERA (now QinetiQ,
Farnborough) and is made available by IHS ESDU under the terms of
an agreement with QinetiQ.

The disk containing the files relating to VGK also contains a
‘library' of files of aerofoil coordinates – see Appendix A for the
list of aerofoils provided.

The Data Items dealing with VGK, of which this is the second,
are:

Part 1: Principles and results,

Part 2: User manual,

Part 3: Estimation of a separation boundary in transonic
flow,

Part 4: Use of VGK to calculate excrescence drag at subsonic
speeds,

Part 5: Design to a specified upper-surface pressure
distribution,

Part 6: Aerofoil with simple hinged flaps,

Part 7: VGK for Windows ^TM.

This Item describes the use of the variant of the VGK program
suite that can be run in Microsoft Windows from a Command Window.
Sufficient information is given in this Item to obtain results from
VGK, but Part 1 should be referred to for the principles and
performance of the method, so that the results obtained may be
properly assessed. Typical computing time for a single run of VGK
using a 80486 DX processor is 90 seconds and using a Pentium 90
processor is 30 seconds.

The file name convention adopted for VGK runs is given in
Section 2.1. A description of the various types of VGK run is given
in Section 3. The functions of the files and the way they are used
and produced by the programs VGKCON (the VGK ‘control' program) and
VGK are presented in Section 4.

The specification of the file providing the coordinates of the
aerofoil of interest is given in Section 5. Results of example VGK
runs are given in Section 6. Section 7 contains a description of
some of the problems that may be encountered with VGK runs and how
they might be overcome.

Detailed commands for using the programs are given in Section 8.
The production of graphical output is dealt with briefly in Section
9.

* VGK has been subsequently extended (as BVGK) to deal
additionally with the effects of low Reynolds numbers and with
boundary-layers with (small) regions of separation, see Part 1,
Section 6.

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