Boundary-Layer Transition Prediction for Laminar Flow Control (Invited)

2015 ◽  
Author(s):  
Jeffrey Crouch
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Flow Control ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Transition Prediction ◽  
Laminar Flow Control

Status and perspectives of laminar flow

2005 ◽  
Vol 109 (1102) ◽  
pp. 639-644 ◽  
Author(s):  
G. Schrauf
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Flow Control ◽  
Boundary Layer Transition ◽  
Technology Readiness ◽  
Layer Transition ◽  
The Status ◽  
Natural Laminar Flow ◽  
Laminar Flow Control

AbstractAfter identifying the ecological and economic drivers for use of laminar flow technology, we outline the mechanisms of laminarturbulent boundary layer transition and review the status of natural laminar flow (NLF) and hybrid laminar flow control (HLFC). New ways to reduce the complexity of HLFC systems are presented, and the remaining steps to achieve technology readiness are discussed.

Keel Design for Low Viscous Drag

1987 ◽  
Author(s):  
Clifford J. Obara ◽  
C. P. van Dam
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Laminar Boundary Layer ◽  
Leading Edge ◽  
Boundary Layer Transition ◽  
Viscous Drag ◽  
Hydrodynamic Characteristics ◽  
Sweep Angle ◽  
Layer Transition ◽  
Layer Flow

In this paper, foil and planform parameters which govern the level of viscous drag produced by the keel of a sailing yacht are discussed. It is shown that the application of laminar boundary-Layer flow offers great potential for increased boat speed resulting from the reduction in viscous drag. Three foil shapes have been designed and it is shown that their hydro­dynamic characteristics are very much dependent on location and mode of boundary-Layer transition. The planform parameter which strongly affects the capabilities of the keel to achieve laminar flow is lea ding-edge sweep angle. The two significant phenomena related to keel sweep angle which can cause premature transition of the laminar boundary layer are crossflow instability and turbulent contamination of the leading-edge attachment line. These flow phenomena and methods to control them are discussed in detail. The remaining factors that affect the maintainability of laminar flow include surface roughness, surface waviness, and freestream turbulence. Recommended limits for these factors are given to insure achievability of laminar flow on the keel. In addition, the application of a simple trailing-edge flap to improve the hydrodynamic characteristics of a foil at moderate-to-high leeway angles is studied.

A Surrogate-Based eN Method for Compressible Boundary-Layer Transition Prediction

2021 ◽  
pp. 1-14
Author(s):  
Han Nie ◽  
Wenping Song ◽  
Zhonghua Han ◽  
Jianqiang Chen ◽  
Guohua Tu
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Transition ◽  
Compressible Boundary Layer ◽  
Layer Transition ◽  
Transition Prediction

An overview of flow control activities at Dassault Aviation over the last 25 years

2016 ◽  
Vol 120 (1225) ◽  
pp. 391-414
Author(s):  
J.-P. Rosenblum
Keyword(s):  
Flow Control ◽  
The United States ◽  
Control Flow ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Flow Separation Control ◽  
Research Activities ◽  
Flow Control Devices ◽  
Laminar Flow Control ◽  
Control Technologies

ABSTRACTIn France, the very first ideas on flow control were developed by Philippe Poisson-Quinton from the Office National d'Etudes et Recherches Aérospatiales (ONERA) in the 1950s. There was some renewal of this research topic in the early 1990s, first in the United States with scientists like Wygnanski and Gad-El Hak, and also in France at the initiative of Pierre Perrier from Dassault Aviation, who triggered a lot of research activities in this field both at ONERA and in the French National Centre for Scientific Research (CNRS) laboratories. The motivation was driven by the applications on Dassault Aviation military aircraft and Falcon business jets in order to contribute to the design, while facilitating performance optimisation and multi-disciplinary compromise. A few examples of flow control technologies, such as forebody vortex control, circulation control, flow separation control or boundary layer transition control using hybrid laminar flow control (HLFC), are presented to illustrate the applications and to explain the methodology used for the design of the flow control devices. The author also emphasises the current reaction of industry with respect to the integration of flow control technologies on an aircraft programme. The conclusion is related to the present status of the French research on this topic and to the next challenges to be addressed.

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