Effects of centerline curvature and cross-sectional shape transitioning in the subsonic diffuser of the F-5 fighter jet

• Published in: Journal of mechanical science and technology Vol. 22; no. 10; pp. 1993 - 1997
• Main Authors: Ibrahim, I. H., Ng, E. Y. K., Wong, K., Gunasekaran, R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Heidelberg Korean Society of Mechanical Engineers 01-10-2008; Springer Nature B.V; 대한기계학회
• Subjects: Control; Cross sections; Curvature; Distortion; Ducts; Dynamical Systems; Engineering; Exact sciences and technology; Flows in ducts, channels, nozzles, and conduits; Fluid dynamics; Fundamental areas of phenomenology (including applications); Industrial and Production Engineering; Intakes; Mathematical analysis; Mechanical Engineering; Physics; Pressure recovery; Studies; Subsonic diffusers; Vibration; 기계공학; Distortion; Cross-sectional shape; Recovery; S-duct; Curved diffuser; F-5; Flow distortion; Pipe flow; Fight aircraft; Prismatic shape; Subsonic flow; Curved pipe; Jets; Diffusers; Vortex flow; Secondary flow; Curvature
• ISSN: 1738-494X; 1976-3824
• DOI: 10.1007/s12206-008-0744-7

Intake geometries result in unwanted secondary flows and formations of vortices which affect the engine performance. This paper investigates the effects of the curvature and cross-sectional shape transitioning of the actual F-5 duct. Two additional different geometries were set up to isolate each parameter, a circular cross-sectional duct with similar centerline configuration and a straight duct with similar cross-sectional transitioning as the F-5 duct. To measure the efficiency of duct flow, the distortion index (DC (60)) and pressure recovery are used. It is found that the straight duct with similar cross-sectional transitioning as the F-5 intake resulted in a 2.1% increase in pressure recovery and an 86% decrease in distortion when compared with the baseline intake. Also, the baseline intake resulted in a 0.5% increase in pressure recovery and a 15% decrease in distortion compared to the constant circular cross-sectional duct.