scholarly journals Study of Leading-Edge Dimple Effects on Airfoil Flow Using Tomographic PIV and Temperature Sensitive Paint

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 184
Author(s):  
Adam J. Stolt ◽  
Al Habib Ullah ◽  
Jordi Estevadeordal
Keyword(s):  
Measurement Techniques ◽  
Leading Edge ◽  
Boundary Layer Transition ◽  
Temperature Sensitive ◽  
Layer Transition ◽  
Tomographic Piv ◽  
Current Configuration ◽  
Airfoil Blades ◽  
Temperature Sensitive Paint ◽  
Set Up

Airfoil blades can experience a significant change of angle of attack during operation cycles, which may lead to static or dynamic stall in various applications. It is unclear how elements distributed at the leading edge would affect the aerodynamic performance and stall behaviors. In the present study, a distributed dimples configuration was investigated and compared to a baseline smooth NACA0015 airfoil at low Reynolds numbers. Two- and four-camera, tomographic particle image velocimetry (PIV), and temperature sensitive paint (TSP) techniques were set up to gather flow and surface information near the curved leading-edge surface and to study flow separation. Results suggest that distributed dimples configuration create abrupt separation leading to stall and induce a similar stall compared to the smooth model. However, the stall is induced more abruptly and with different flow patterns. Results show that patterns of separated shear layer at stalled conditions were enhanced by the current configuration. Effect of these structures on the boundary layer transition were also analyzed based on combined tomographic PIV and TSP measurement techniques.

scholarly journals Recent progress in the study of transition in the hypersonic boundary layer

2018 ◽  
Vol 6 (1) ◽  
pp. 155-170 ◽  
Author(s):  
Cunbiao Lee ◽  
Shiyi Chen
Keyword(s):  
Boundary Layer ◽  
Fluid Mechanics ◽  
Rayleigh Scattering ◽  
Measurement Techniques ◽  
Boundary Layer Transition ◽  
Temperature Sensitive ◽  
Hypersonic Boundary Layer ◽  
Layer Transition ◽  
Engineering Research ◽  
Near Wall

Abstract Turbulence is a universal form of fluid motion. It is the key issue in fluid mechanics. Very recently, it has become a bottleneck in some key engineering research of national importance, such as aeronautics, astronautics and navigation. Developed turbulence and the onset of turbulence, i.e. transition, are two interrelated parts of turbulence. The hypersonic boundary-layer transition is a strategic focus in the fluid mechanics community. This article reviews recent developments in the study of the hypersonic boundary-layer transition, research facilities and experimental techniques. The hypersonic quiet wind tunnel is introduced as a necessary device to obtain real flight data in near space. Near-wall measurement techniques, such as temperature-sensitive paint, near-wall particle image velocimetry and Rayleigh-scattering visualization, are shown. The most important issues in the recent development of the transition in the hypersonic boundary layer are addressed. The instability and nonlinear interaction of different instability modes are discussed. The recent contributions from China, especially at Peking University, are also introduced.

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