35 * An Experimental Study on the Characteristic of ean Flow in Supersonic Boundary Layer Transition Shoji SAKAUE, Department of Aerospace Engineering, Osaka Prefecture University ichio NISHIOKA, Department of Aerospace Engineering, Osaka Prefecture University (Received 3 September, 8; in revised form 9 arch, 9 To obtain a better understanding of the mechanism for supersonic boundary layer transition, we examine a ach.86 supersonic boundary layer along a small tunnel nozzle wall with rectangular cross section using Pitot-tube and quantitative schlieren optical system calibrated by wedge prism method. ean flow profiles in transition process are obtained by measuring distributions of density gradients. The results clearly show that near-wall density gradients start to increase at the beginning of transition, suggesting the occurrence and growth of disturbances which carry the mainstream fluid to the wall neighborhood and the near-wall fluid to the outer edge. It is also shown that inclined vortical structures our schlieren system visualizes are similar to the structures observed in supersonic turbulent boundary layers. Furthermore, the result obtained by the quantitative schlieren method indicates the transition to occur earlier compared with the corresponding obtained at the span center of the tunnel. It is suggested that the transition occurs near the nozzle corner region first and the turbulence is spread by a process of transverse contamination. (KEY WORDS: Supersonic boundary layer, Boundary layer transition, Quantitative schlieren method, Transverse contamination *599-853 E-mail: sakaue@aero.osakafu-u.ac.jp
36 Re = TS TS.3 ~ % e N TS e N N = e N TS TS TS Re = Re = 3,3 4-6 7-9 Coles.97 Re = 94 Re = 39 Re <. Re -4 x y z x = 3 mm 3 mm.7 mm x = 67 mm 8 mm x = 6 mm
37 (mm ach number y (mm - 4 6 8.5 8. (c 6 4..5 ach number Re θ. - 4 6 8 Re θ (mm. mm.8 mm Flash lamp Concave mirror Flash lamp controller Pulse generator irror Test section (c Re x irror Camera Concave mirror Knife-edge Camera controller.6 kpa9 K U x = 67 mm =.98U = 56 m/s x = 6 mm =.96U = 5 m/s Re = 574x = 67 mm~ 94 x = 6 mmx = 6 mm Coles Re. mm y. mm.8 mm x = 7 mm ~ 6 mm z = mm uy p/y = Pr = u u U 3 5.3 3 8 ns. mm f = mm 56 BP PC.86 mm.86 mm PC (
38 4 /y I f y y y f y fkd 6-8 K Gladstone -Dale.59 4 m 3 /kg = 67.4 nmd /fkd 7,8 y f y /y 6~8 3 3. 4 x = 7 mm ~ mm u y U.995 U x = 9 mm x = mm 5 Re 4 x = 9 mmre = 684 x mm u Van Driest 9 U c u / U c Tw T du A A U A T w T U ( u sin (3 w Reichardt inner layer profile Finley wake function 4 x y Re θ..5 U c x = 7mm...4.8...5 u/u x = 9mm...4.8. 3 5 5 5 u/u 5 x ln y y C e y Simulation results for laminar flow / y 3 y e...4.8. b y y 6 3 y 4 C C ln, =.4, C = 4.9, =, b =.33 u.6..5..5 x = 8mm...4.8. u/u x = mm u/u Simulation results for laminar flow 4 6 8 4 6 (4
39 3 6 x = mm ~ 6 mm Van Driest U c (4 x = 6 mm =.53 mm Re = 59 u c f c f Re 4 c f inc sin A c (5 f, Re inc Re w c f inc, Re inc 7 Karman-Schoenherr Blasius Uc + Uc + 6 x Van Driest U c (4 c 5 5 5 f inc 7.8 log Re 5. log Re inc inc / 4.6 Re f inc x = mm y + x = 4mm y + inc Uc + 5 5 5 Reichardt & Finley Uc + 6. U + c = y + U + c = κ ln y + + C x = mm (6 c (7 4 x = 9 mm 5 5 5 5 5 5 y + x = 6mm y + cf inc 6 5 4 3 mm mm mm Karman-Schoenherr Blasius 3mm 4mm 5mm 6mm 7mm 8mm 9mm 5 5 Reθ inc 7 Karman-Schoenherr(6 Blasius(7 Re = 684x = mmre = 448 x = 4 mmre = 98 x = 7 mm =.U = 58 m/s x = 6 mm =.86U = 49 m/s 3. 8 6 x = 6 mm 8 (c Pr = ( U f y y/ >.36y > mm ( /fkd (c y/ >.36 u (4 y mm y.5 mm
3. Quantitative schlieren. Simulation results for laminar flow Reichardt & Finley...8.. (c.8.8.6.6.6.4.4.4......5. ( y / δ..6.8.....4.6.8.. ρ / ρ u/u 8 x = 6 mm y (c u (4 3 4 5 6 7 8.... y (mm y (mm 9 4 /y 4.. y (mm. 8 9 3 4 5 6.. y (mm 4 /y 8 y mm 3.3 /y u/y (
3..8 Quantitative schlieren Simulation results for laminar flow.. x = mm.8 x = mm.8 x = 3mm y (mm.6.4 y (mm.6.4 y (mm.6.4... y (mm y (mm....8.6.4....5.4.8. x = 4mm. x = 5mm x = 6mm.4.8. y (mm x = 7mm x = 8mm x = 9mm. y (mm...8.6.4...5.4.8..4.8. y (mm y (mm...5....5.4.8..4.8...4.8...4.8...4.8. x y ˆ uˆ m ˆ uˆ y y uˆ u U, ˆ, m y/.3 8. y/.6 (8 9, 4 /y /y 9 y x = 9 mm x = mm ~ mm mm
3. Quantitative schlieren.5 3. y (mm..5 x = mm y (mm...5 x = mm y (mm.. x = mm. 3....4.6.8. (/mm. 3....4.6.8. (/mm. 3....4.6.8 (/mm y (mm.. x = 3mm y (mm.. x = 4mm y (mm.. x = 5mm....4.6.8 (/mm.....3.4.5 (/mm.....3.4.5 (/mm 3.4 4 x 9 mm 9 f y /y y mm 8 /y x = 9 mm /y =.336 3 kg/m 4 /y.43 3 kg/m 4 x.86 mm x 3 mm 6 x = mm =.9 mm y y x 9 mm 4 x 9 mm x 4 mm 9 x = 8 mm
33.. y (mm 4.. y (mm (c 3 8 9 3 4 5 6.. y (mm 3 v mm x 5 mm f y /fkd 8 x = 4 mm, 5 mm x = mm 5 mm 3 y ~ (c x 4 mm 5,6 (8 (8 (8 3 mm x 3 mm 3 x = 5 mm x = 8 mm (c x = 85 mm x = mm 4 y y / y / x.86 mm y x x = 9 mm Re = 684 x = mm Re = 448 / x = 4 mm x = 6 mm Re = 54
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