Effectiveness of Micro-Blowing Technique in Adverse Pressure Gradients
Abstract
The impact of the micro-blowing technique (MBT) on the skin friction and total drag of a strut in a turbulent, strong adverse-pressure-gradient flow is assessed experimentally over a range of subsonic Mach numbers (0.3<M<0.7) and reduced blowing fractions (0<2F/C(f,0)< 1.75). The MBT-treated strut is situated along the centerline of a symmetric 2-D diffuser with a static pressure rise coefficient of 0.6. In agreement with presented theory and earlier experiments in zero-pressure-gradient flows, the effusion of blowing air reduces skin friction significantly (e.g., by 60% at reduced blowing fractions near 1.75). The total drag of the treated strut with blowing is significantly lower than that of the treated strut in the limit of zero-blowing; further, the total drag is reduced below that of the baseline (solid-plate) strut, provided that the reduced blowing fractions are sufficiently high. The micro-blowing air is, however, deficient in streamwise momentum and the blowing leads to increased boundary-layer and wake thicknesses and shape factors. Diffuser performance metrics and wake surveys are used to discuss the impact of various levels of micro-blowing on the aerodynamic blockage and loss.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2001
- Accession Number
- ADA385733
Entities
People
- Danny P. Hwang
- Gerard E. Welch
- Jerry R. Wood
- Louis M. Larosiliere
Organizations
- National Aeronautics and Space Administration