An experimental study on the effect of square grooves on decay characteristics of a supersonic jet from a circular nozzle

• Published in: Journal of mechanical science and technology 2018, 32(10), , pp.4721-4729
• Main Authors: Ilakkiya, S., Sridhar, B. T. N.
• Format: Article
• Language: English
• Subjects: Control; Decay; Dynamical Systems; Effectiveness; Emission; Engineering; Grooves; Industrial and Production Engineering; Mach number; Mechanical Engineering; Nozzles; Vibration; 기계공학
• ISSN: 1738-494X; 1976-3824
• DOI: 10.1007/s12206-018-0919-9

In this experimental work, the effect of square grooves on the structure of a supersonic jet emanating from a circular nozzle has been investigated at three different nozzle inlet total pressures i.e 360 kPa, 550 kPa and 720 kPa. The nominal exit Mach number is 1.8. A new empirical relation for predicting the supersonic core length for grooved nozzle has been suggested. Further, a new parameter “groove effectiveness” has also been suggested to quantify the effect of the groove by using the total pressure data in the supersonic core length. Experimental results suggest that at higher nozzle inlet total pressure, the groove effectiveness plays a minor role. From the jet centreline total pressure data, supersonic core length, the locations at which 50 % and 90 % decay occurs have been obtained. It has been observed that higher groove effectiveness is associated with smaller values of supersonic core length, L 50% and L 90% . Schlieren images of the jet structure shows unsymmetrical shock pattern of jets emanating from a single grooved nozzle.