Project Title:

Aircraft Drag Reduction using Distributed Suction and Adaptive Control Techniques

  94-1		 02.03  	4151



  Aircraft Drag Reduction using Distributed Suction and Adaptive 

  Control Techniques

Abstract:

Implementing laminar flow control (LFC) for airplanes using 

suction through slotted or perforated surfaces, promises two 

to three times the current achievable range (full chord 

laminar flow is achieved over aircraft wings). Because of 

variations in surface pressure, several suction compartments 

are necessary under the wing surface. The maximum benefit of 

LFC is dependent on using minimum suction rates in the various 

suction panels and compartments. 

The proposed innovation is to design an LFC controller to 

optimize the flow in various suction panels to keep the 

transition at a predetermined location on the wing. This 

innovative monitoring and flow control system will measure the 

boundary layer state, i.e. transition location in real time, and 

use this to adjust the suction flow rates to continuously vary 

and maintain extensive region of laminar flow on LFC airplanes. 

A key component of the innovation is the use of a non-intrusive 

method to measure the boundary layer state on the wing using 

several flush mounted miniature microphones, buried under the 

suction surface. Flow control based on the microphones is non-

intrusive, more sensitive, and rugged than the other more 

conventional methods.


An adaptive boundary layer control system will provide high pay-

off in terms of requiring minimum required power to run the 

suction system, and could be highly beneficial to commercial 

subsonic and supersonic transports and military airplanes 

designed for extremely long ranges. The proposed innovation will 

also be useful in applications such as reducing the high-speed 

buffet fatigue loads on high-speed transport airplanes, which 

will be possible by supplying boundary layer suction in and 

downstream on the shock region. Real-time feedback transition 

control system proposed will be necessary for every flying LFC 

airplane in the future.  


Key Words


Innovative Aerodynamic Technologies

534-C Wythe Creek Road

Poquoson, Virginia  23662