ESDU Engineer

VGK Aerofoil Code for Windows

A “WindowsTM” version of the VGK aerofoil code is soon to be added to Volume 3 of the ESDU Transonic Aerodynamics Series. This will provide a simplified, menu-driven input together with graphical output of the computational grid and of all flow parameters around the aerofoil.

VGK is a CFD (computational fluid dynamics) method for predicting the aerodynamic characteristics of a two-dimensional 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. VGK was developed over a period of years at RAE and is made available by ESDU under the terms of an agreement with MoD. Crown copyright is retained in the VGK source code.

The “WindowsTM” version of VGK to be issued initially is that described fully in Data Item No. 96028 (see list of titles below). That Item describes the main features of the VGK method, including the inviscid and viscous flow elements, the computational grids and the solution process. The precise forms of finite-difference scheme and iteration procedure employed in a particular VGK ‘run’ are governed by a number of parameters. The values of these parameters may be selected by the user. Default values for these parameters are given, together with comments on the effects on VGK results of variations from these values.

Because of its good performance, VGK can be utilised effectively to investigate a number of factors, such as:
Influence of aerofoil geometry (profile and camber) changes on aerodynamic characteristics at and around cruise conditions,
Influence of changes in Mach number, Reynolds number and transition locations,
Influence of deflection through small angles of leading- and trailing-edge flaps,
Influence of over-fixing transition in wind-tunnel tests on aerofoils.

Existing Data Items and versions of the VGK method for two-dimensional aerofoils:

Item No.
96028 Part 1: Principles and results.
96029 Part 2: User manual for operation with MS-DOS and UNIX systems.
97030 Part 3: Estimation of a separation boundary in transonic flow.
98031 Part 4: Estimation of excrescence drag at subsonic speeds.
99032 Part 5: Design to a specified upper-surface pressure distribution.
01033 Part 6: Aerofoil with simple hinged flaps.

Dave Mitchell is the Group Head responsible for Transonic Aerodynamics. He can be contacted at dmit@esdu.com