TY - JOUR
T1 - Shock structures and instabilities formed in an underexpanded jet impinging on to cylindrical sections
AU - Mason-Smith, Nicholas James
AU - Edgington-Mitchell, Daniel Michael
AU - Buchmann, Nicolas
AU - Honnery, Damon Robert
AU - Soria, Julio
PY - 2015/3/12
Y1 - 2015/3/12
N2 - Schlieren visualisations are used to investigate the influence of cylindrical surface curvature on both the time-invariant and oscillatory behaviour of the shock structures within underexpanded jets impinging on to a surface. At moderate standoff distances (Formula presented.), the impingement surface curvature affects the temporal behaviour of the flow significantly, but with only slight variations in the time-invariant structure. A convex surface curvature constrains flapping oscillations to a single plane, the normal of which is parallel to the cylinder axis; the oscillation frequency is largely unaffected. For the standoff distances and nozzle pressure ratios studied, concave surface curvature suppresses the formation of impingement tones. A mechanism is proposed whereby entrainment of the recirculated wall jet flow alters the shear layer receptivity to acoustic disturbances, breaking the acoustic feedback loop that drives the jet oscillations.
AB - Schlieren visualisations are used to investigate the influence of cylindrical surface curvature on both the time-invariant and oscillatory behaviour of the shock structures within underexpanded jets impinging on to a surface. At moderate standoff distances (Formula presented.), the impingement surface curvature affects the temporal behaviour of the flow significantly, but with only slight variations in the time-invariant structure. A convex surface curvature constrains flapping oscillations to a single plane, the normal of which is parallel to the cylinder axis; the oscillation frequency is largely unaffected. For the standoff distances and nozzle pressure ratios studied, concave surface curvature suppresses the formation of impingement tones. A mechanism is proposed whereby entrainment of the recirculated wall jet flow alters the shear layer receptivity to acoustic disturbances, breaking the acoustic feedback loop that drives the jet oscillations.
KW - Aeroacoustics
KW - Impinging jet
KW - Schlieren
UR - http://goo.gl/pGTD8B
U2 - 10.1007/s00193-015-0561-8
DO - 10.1007/s00193-015-0561-8
M3 - Article
SN - 0938-1287
VL - 25
SP - 611
EP - 622
JO - Shock Waves
JF - Shock Waves
IS - 6
ER -