Experimental Investigation of Laminar Separation Bubbles

Abstract

Laminar separation bubbles play an important role in the flow about airfoils at Reynolds numbers below 3 millions in incompressible flows. Drag as well as stall behaviour can be deteriorated considerably. Designing or analysing airfoils in this flight regime, with some success, requires understanding of the flow phenomena envolved in the formation of these regions with locally separated flow. Detailed experimental studies were carried out on laminar separation bubbles that formed near the midchord of different airfoils at Reynolds numbers from 0.7 to 3 millions. Static pressure, hot wire anemometry, and flow visualisation data were acquired. The data were used to evaluate the applicability of existing separation bubble models. Some details of the materials gathered are presented in the following context.