ESDU 97020: Slope of aerofoil lift curve for subsonic flow

Abstract:

ESDU 97020 gives a method for predicting the linear viscous lift-curve slope of symmetric and cambered aerofoils in subcritical compressible flow. The VGK program (see ESDU 96028 and 96029 in the Transonic Aerodynamics Series) was applied to a range of NACA aerofoils and also to aerofoils with complex camber lines to derive graphs of a reduction factor to be applied to the inviscid lift-curve slope from ESDU 72024. Investigation of the effect of aerofoil geometry on lift-curve slope showed that geometry effects on the reduction factor could be adequately characterised by the use of an equivalent trailing-edge angle based on thickness at 0.9 and 0.99 of chord for the symmetric aerofoils, with the additional requirement of a trailing-edge upper surface angle based on ordinates at the same positions for the cambered aerofoils. The method also requires the assumption of transition positions on the upper and lower surfaces, and the Reynolds and Mach numbers. It applies for fully-attached boundary layers but becomes unreliable if lift-curve slope is strongly dependent on transition movement with angle of attack. It predicts the reduction factor to within 0.005. A fully worked example illustrates the use of the method and the aerofoils used in its derivation are listed.

A computer program of the method is included as part of ESDU LiCrA Toolbox apps and ESDUpacs A9931 and B9931 from (ESDU 99031). See the 'Software' tab, above.

Indexed under:

Details:

Data Item ESDU 97020
Format:	PDF with software
Status:	Original, issued 01 Sep 1997 Published in Release 2000-03 (init)
Previous Releases:	None available
ISBN:	978 1 86246 022 5

The Data Item document you have requested is available only to subscribers.

Subscribers login here.
If you are not an ESDU subscriber find out how to subscribe.

This Data Item is complemented by the following software:

Toolbox Apps

Name

Details

Toolbox LiCrA-2D Run

Title

ESDU LiCrA: 2D Lift Curve Aerodynamics for Aerofoils

Version

1.0

Details

LiCrA 2D calculates the maximum lift coefficient, the lift coefficient at zero angle of attack and the lift curve of aerofoil sections with or without high-lift devices deployed at low speeds.

Calculations can be made for the aerofoil when there are no high-lift devices deployed but the prediction of the shape of the non-linear part of the lift curve should be treated with caution because it employs a technique developed for use when high-lift devices are deployed. The method is intended for use only for free-stream Mach numbers up to about 0.25.

Toolbox LiCrA-3D Run

Title

ESDU LiCrA: 3D Lift Curve Aerodynamics for Wings and Wing/Body Combinations

Version

1.0

Details

LiCrA 3D calculates the maximum lift coefficient, the lift coefficient at zero angle of attack and the lift curve of straight-tapered wings with or without high-lift devices deployed at low speeds. The basic wing (no devices deployed) may have camber and twist. The program includes methods that allow for the presence of a fuselage.

For completeness, calculations can be made for the wing when there are no high-lift devices deployed but the prediction of the shape of the non-linear part of the lift curve should be treated with caution because it employs a technique developed for use when high-lift devices are deployed. The method is intended for use only for free-stream Mach numbers up to about 0.25. No allowance is made for ground effect.

If required, it will also calculate the spanwise position of the section of the basic wing that has the peak loading due to angle of attack.

ESDU 97020

Slope of aerofoil lift curve for subsonic two-dimensional flow.