An experimental investigation of the turbulent boundary layer over a wavy wall

摘要: An experimental investigation of turbulent boundary layer flow over wavy surfaces was conducted at low speed. Two models with the ratio amplitude to wave length a/λ = 0.03 and lengths λ 6" 12" were tested in an open-circuit wind tunnel. The free stream velocity 15.4 m/sec, giving Reynolds number Re 2.54 X 10^4 per inch. Boundary-layer thickness varied from δ 1.5" 4. 1" by means boundary-layer trips various height, order change λ/6. following measurements taken: * Wall pressure distribution Average turbulence level, using a single element hot-wire probe stress distribution, Preston's tube Static total pressures Turbulence intensities shear X-array probe. appreciable modulation all quantities, imposed boundary, is observed throughout investigation. much lower than predicted uniform, inviscid theory slightly non-symmetric. distribution has peak C_f/C_fo 1.2 upstream crest dip 0. 6 trough. decays exponentially outer while its gradient decreased toward surface wall layer. distributions near show oscillatory superimposed on reference flat plate profiles. oscillations decay edge layer, so that part quantities are practically independent longitudinal position. It found Coles' Law does not apply present situation because slope semi-logarithmic portion A presentation profiles suggested through use defined U^t (U^2 + 2(p–p_∞)/p)^(1/2). This quantity obeys Wake. Mixing eddy viscosity based derivative ∂U^t/∂y reduced into one curve which distribution.