Latest revision as of 14:58, 11 February 2017

RAE M2155 Wing

Application Challenge 1-02 © copyright ERCOFTAC 2004

Overview of Tests

The wind tunnel experiments were designed to provide data for the validation of CFD viscous methods, and in particular of the turbulence models used in the numerical simulations. The test cases studied provide examples of flows with severe adverse pressure gradient, including those with shock waves, and leading in some cases to separation. Two forms of separation have been met in the experiments; a trailing-edge separation and a shock-induced separation. The cases with shock-induced separation has reattachment upstream of the trailing edge.

Pressure distributions on the tunnel walls have been measured, and the interference effects of the tunnel walls has been determined by using the method outlined by Ashill and Weeks. The interference of the tunnel walls was found to be significant particularly for the higher free stream Mach numbers. The computational studies, therefore need to be performed as internal flow calculations, making tunnel corrections unnecessary.

A large set of data, consisting of pressure distributions on both the wing and on the tunnel wall for a wide range of incidences (1.5 deg. to 4.5 deg.) and Mach numbers (0.6 to 0.87), at a Reynolds number (based on the geometric men chord) of 4 million, are presented in the test reports [1]. Surface shear stress lines were observed using oil flows, and photographs of these are included in the test report [1]. For the four test conditions chosen for a more detailed study, skin friction and mean flow profile data in the boundary layers and wakes are available in addition to surface pressures. The test data form part of the AGARD validation database [2].

In order to measure the pressure distribution on the surface of the wing, a total of 308 holes on the upper surface and of 161 holes on the lower surface have been drilled into the wing. The surface pressure holes have been drilled normal to the surface into small cavities inside the wing with hypodermic tubing connected from each cavity to pressure switches. The pressure switches enable each manometer to be used for six pressure holes. The static pressure distributions are derived from measurements using 78 manometers and a method of switching the pressure lines from the model to the manometers.

At each span-wise location at which pressure distributions have been measured, the normal force coefficients have been determined. The normal force coefficients have been integrated on the whole wing, and therefore it is possible to determine inviscid values of the aerodynamic coefficients.

A number of runs have been made to study the surface flow by using a very thin layer of oil of high viscosity. Photographs of the oil flow were obtained and are reported in [1]. Skin friction coefficients have been obtained by using the razor-blade method.

Boundary layer measurements, consisting of the local static pressure and velocity, have also been obtained.

Table EXP-A Summary Description of all Test Cases
NAME	GNDPs		PDPs	MPs
	Re	Mach	Incidence (deg)	Detailed Data	DOAPs
EXP 11	4.1x10⁶	0.744	2.5	C_p, C_f, U	C_N
EXP 12	4.1x10⁶	0.806	2.5	C_p, C_f, U	C_N
EXP 13	4.1x10⁶	0.846	1.5	C_p, C_f, U	C_N
EXP 14	4.1x10⁶	0.854	1.5	C_p, C_f, U	C_N

Table EXP-B Summary Description of all Measured Parameters and Available Data Files
	MP 1 C_P	MP 2 C_f	MP 3 U	DOAPs, or other miscellaneous data
EXP 12	✔ac102x12cp02.dat	✔ac102x12cf02.dat	✔ac102x12bla.dat	✔ac102xdoap.dat
	✔ac102x12cp03.dat	✔ac102x12cf03.dat	✔ac102x12blb.dat
	✔ac102x12cp04.dat	✔ac102x12cf04.dat	✔ac102x12blc.dat
	✔ac102x12cp05.dat	✔ac102x12cf05.dat	✔ac102x12bld.dat
	✔ac102x12cp06.dat	✔ac102x12cf06.dat	✔ac102x12ble.dat
	✔ac102x12cp07.dat	✔ac102x12cf07.dat	✔ac102x12blf.dat
	✔ac102x12cp08.dat	✔ac102x12cf08.dat
	✔ac102x12cp095.dat
EXP 14	✔ac102x14cp02.dat	✔ac102x14cf02.dat	✔ac102x14bla.dat	✔ac102xdoap.dat
✔ac102x14cp03.dat	✔ac102x14cf03.dat	✔ac102x14blb.dat
✔ac102x14cp04.dat	✔ac102x14cf04.dat	✔ac102x14bld.dat
✔ac102x14cp05.dat	✔ac102x14cf05.dat	✔ac102x14ble.dat
✔ac102x14cp06.dat	✔ac102x14cf06.dat	✔ac102x14blf.dat
✔ac102x14cp07.dat	✔ac102x14cf07.dat
✔ac102x14cp08.dat	✔ac102x14cf08.dat
✔ac102x14cp095.dat

Test Case EXP-1

Description of Experiment

Four Test Conditions have been studied in detail.

Boundary Data

Pressure distributions on the tunnel walls have been measured, and the interference effects of the tunnel walls has been determined by using the method outlined by Ashill and Weeks. The interference of the tunnel walls was found to be significant particularly for the higher free stream Mach numbers. The computational studies, therefore need to be performed as internal flow calculations, making tunnel corrections unnecessary.

Measurement Errors

The accuracy of the data is [2] :

• Mach number : ± 0.0015

• Model incidence : ± 0.01°

• Measured pressure coefficients : Δp/H = ± 0.0003 based on calibration of transducer only

During the tests to obtain the wing surface and tunnel wall pressures, the free stream Mach number has been kept within ±0.002 of the required value. In addition, during measurements of boundary layer profiles , the location of the shock waves on the upper surface of the wing were monitored. The free stream Mach number was adjusted to keep the shock location fixed for each test case condition.

The wing pressures have been measured many times during the measurements of the boundary layers, and during the skin friction measurements. Some of these have been measured two years later the experimental test campaign. Some inconsistent values at 5% chord, caused by a local effect of the transition trip, was found.

Some repeat checks of the boundary layer measurements were possible because more than one probe support arm was used for a complete boundary layer profile.

Measured Data

The following data are available [1]:

• Test section wall pressures

• Surface pressures normalized with respect to the free stream total pressure at y/b=0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.95

• Skin friction coefficients based upon local flow conditions at y/b= 0.2,0.3,0.4,0.5,0.6,0.7,0.8

• Boundary layer and wake measurements from pitot tubes and yawmeters

q Integral quantities based upon local flow conditions and in terms of root chord.

q Velocity within a shear layer normalized with respect to the velocity determined from total pressure at the edge of the layer and local static pressure, and static pressure divided by the free stream total pressure at the following stations :

A)	x/c = 0.4342,	y/b = 0.3500
B)	x/c = 0.4023,	y/b = 0.7710
C)	x/c = 0.7442,	y/b = 0.7982
D)	x/c = 0.8508,	y/b = 0.2989
E)	x/c = 1.0501,	y/b = 0.3526
F)	x/c = 1.0498,	y/b = 0.7633

Oil flow visualization for both the upper and lower surface of the wing are reported in [1].

The data have not been corrected from the tunnel wall effects also if these effects have been deduced from the measured tunnel wall pressures.

The model was mounted on a wall of the tunnel and the thickness of the boundary layer was known.

The deformation of the wing was found to be negligible.

EXP12 :

ac102x12cp02.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp03.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp04.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp05.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp06.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp07.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp08.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cp095.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x12cf02.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x12cf03.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface))

ac102x12cf04.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x12cf05.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface))

ac102x12cf06.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x12cf07.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface))

ac102x12cf08.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x12bla.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x12blb.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x12blc.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x12bld.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x12ble.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x12blf.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

EXP14 :

ac102x14cp02.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp03.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp04.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp05.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp06.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp07.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp08.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cp095.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c, C_P)

ac102x14cf02.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf03.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf04.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf05.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf06.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf07.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14cf08.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: x/c (upper surface), C_f (upper surface), x/c (lower surface), -C_f (lower surface))

ac102x14bla.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x14blb.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x14bld.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x14ble.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

ac102x14blf.dat (ASCII file; headers: Mach number, Reynolds number, angle of incidence; columns: Z/C, U/U_P, P/H)

References

[1] M.C.P. Firmin, M.A. McDonald. Measurements of the flow over a low-aspect ratio wing in the Mach number range 0.6 to 0.87 for the purpose of validation of computational methods. Part 1: wing design, model construction, surface flow. Vols. 1 & 2, D.R.A. Technical Reports 92016, 1992.

[2] AGARD-AR-303, Vol II, Test Case B1.1, 1994

Contributors: Pietro Catalano - CIRA; QinetiQ

Site Design and Implementation: Atkins and UniS