Experimental investigation of a blunt trailing edge flow field with application to sound generation
- 257 Downloads
The unsteady lift generated by turbulence at the trailing edge of an airfoil is a source of radiated sound. The objective of the present research was to measure the velocity field in the near wake region of an asymmetric beveled trailing edge in order to determine the flow mechanisms responsible for the generation of trailing edge noise. Two component velocity measurements were acquired using particle image velocimetry. The chord Reynolds number was 1.9 × 106. The data show velocity field realizations that were typical of a wake flow containing an asymmetric periodic vortex shedding. A phase average decomposition of the velocity field with respect to this shedding process was utilized to separate the large scale turbulent motions that occurred at the vortex shedding frequency (i.e., those responsible for the production of tonal noise) from the smaller scale turbulent motions, which were interpreted to be responsible for the production of broadband sound. The small scale turbulence was found to be dependent on the phase of the vortex shedding process implying a dependence of the broadband sound generated by the trailing edge on the phase of the vortex shedding process.
KeywordsVorticity Particle Image Velocimetry Streamwise Velocity Turbulent Motion Turbulent Length Scale
This research was made possible through funding from the US Office of Naval Research under Grant No. N00014-03-1-0105, Dr. Ron Joslin, program manager.
- Blake WK (1986) Mechanics of flow-induced sound and vibration, vol II. Academic, Orlando, FLGoogle Scholar
- Blake WK, Gershfeld JL (1989) The aeroacoustics of trailing edges. In: Frontiers in experimental fluid mechanics (A90-26059 10-34). Springer, Berlin Heidelberg New York, pp 457–532Google Scholar
- Brooks TF, Hodgson TH (1981) Trailing edge noise prediction from measured surface pressures. J Sound Vib 78(1):69–117Google Scholar
- Devenport WJ, Muthanna C, Ma R, Glegg S (2001) Two-point descriptions of wake turbulence with application to noise prediction. AIAA J 39:2302–2307Google Scholar
- Gershfeld JL, Blake WK, Knisely CW (1988) Trailing edge flows and aerodynamic sound.In: AIAA thermophysics, plasmadynamics and lasers converence (88-3826-CP). San Antonio, TX, pp 2133–2140Google Scholar
- Holmes P, Lumley JL, Berkooz G (1996) Turbulence, coherent structures, dynamical systems and symmetry. In: Cambridge monographs on mechanics. Cambridge University Press, CambridgeGoogle Scholar
- Howe MS (2003) Theory of vortex sound. Cambridge University Press, CambridgeGoogle Scholar
- Shannon DW, Morris SC, Mueller TJ (2006) Radiated sound and turbulent motions in a blunt trailing edge flow field. Int J Heat Fluid Flow 27(4):730–736Google Scholar