Investigation of hybrid laminar flow control (HLFC) surfaces

Hybrid laminar flow control (HLFC) is an active drag reduction technique. A delay in transition of the boundary layer from laminar to turbulent flow is usually achieved by the application of suction over the first 10–20% of the chord. The design of the suction surface and the chambers underneath the perforated skin represents one of the most significant engineering challenges concerning HLFC. A review of design requirements, candidate materials and drilling methods for the production of the suction surface, is presented. Materials considered include titanium, aluminium and carbon fibre composite. Laser (Excimer or Nd–YAG) and electron beam drilling has been used to produce satisfactory suction panels.