Abstract

The scale difference between the real flight vehicle and the experimental model results in the Reynolds number effect, which makes it unreliable to predict the aerodynamic characteristics of flight vehicles by wind tunnel testing. To understand the mechanism of Reynolds number effects on the aerodynamic characteristics of the supercritical wing that is commonly used in transport aircraft in more detail, surface pressure wind tunnel tests of a transport aircraft reference model with a wing-body configuration were conducted in the European Transonic Windtunnel (ETW) at different Reynolds numbers. There are 495 pressure taps in total equipped on the surface of the test model with the Mach numbers ranging from 0.6 to 0.86 and Reynolds number varying from 3.3 × 106 to 35 × 106. In addition, an in-house developed CFD tool that has been validated by extensive experimental data was used to correct the wing deformation effect of the test model and achieve detailed flow structures. The results show that the Reynolds number has a significant impact on the boundary layer displacement thickness, surface pressure distribution, shock wave position, and overall aerodynamic force coefficients of the transport aircraft in the presence of shock wave and the induced boundary layer separation. The wind tunnel data combined with flow fields achieved from CFD show that the essence of the Reynolds number effect on the aerodynamic characteristics of transport aircraft is the difference of boundary layer development, shock wave/boundary layer interaction, and induced flow separation at different Reynolds numbers.

Highlights

  • The supercritical wing is commonly used in the design of modern transport aircraft by virtue of its excellent transonic performance [1,2,3,4]

  • For providing more detailed and accurate experimental data to investigate the mechanism of Reynolds number effects on aerodynamic characteristics of the transport aircraft and develop Reynolds number effect extrapolation techniques, a transport aircraft model with a typical supercritical wing was tested in an European Transonic Windtunnel (ETW) facility at Reynolds numbers of 3.3, 6.6, 15, 25, and 35 million

  • Due to the complex flow phenomena during the cruise of transport aircraft including shock wave, shock/boundary layer interaction, flow viscosity effect, boundary layer development and separation, the variation in the Reynolds number can result in an apparent change of the flow structure and overall aerodynamic forces

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Summary

Introduction

The supercritical wing is commonly used in the design of modern transport aircraft by virtue of its excellent transonic performance [1,2,3,4]. For providing more detailed and accurate experimental data to investigate the mechanism of Reynolds number effects on aerodynamic characteristics of the transport aircraft and develop Reynolds number effect extrapolation techniques, a transport aircraft model with a typical supercritical wing was tested in an ETW facility at Reynolds numbers of 3.3, 6.6, 15, 25, and 35 million. Combining with cryogenic wind tunnel results and numerical flow structures in the case of the Rey wind tunnel test results, the Reynolds number scaling effects on aerodynamic characteristics of transportfrom aircraft3.3 and×their mechanism analyzed in this are paper. Reynoldsand number effect extra location, edgeare pressure recovery, to boundary layer characteristics, aerodynamic coefficients of the supercritical wing areof discussed systematically niques, which is the priority our research.based on the wind tunnel results and numerical flow structures in the case of the Reynolds number ranging from.

Windnumber
Model Configuration and Test Campaigns
Hz and a sampling of approximate
Computationaltion
Grid Generation
Results and Discussion
Longitudinal aerodynamic differentdynamic dynamic pressures
Itbecan befrom seen from 6Figure
Pressure
Influence of Transition Strips on Reynolds Number Effects
Reynolds
11. Pressure distributions under different
12. Pressure distributions at different angles of attack andReynolds
Reynolds Number Effect on Trailing Edge Pressure Recovery
Reynolds Number Effect on Boundary Layer Thickness
21. Numerical structures at different
Conclusions
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