On the use of a phased heater array for the controlled excitation of arbitrary three-dimensional perturbations in a laminar boundary layer

Abstract

Flush mounted resistive heating elements were used successfully by Liepmann, Brown and Nosenchuck (1981) to excite and control the development of two-dimensional Tollmien-Schlichting waves. Due to increased interest in the three dimensional nature of boundary-layer transition, this technique has recently been extended to provide a means for introducing arbitrary controlled three-dimensional perturbations into a laminar flow. This paper describes the design and operation of a programmable 32-element linear heater array capable of exciting a wide variety of flow disturbances hitherto unobtainable in the laboratory.