TITLE:
On the Existence of Subharmonic Screech in Choked Circular Jets from a Sharp-Edged Orifice
AUTHORS:
Max Kandula
KEYWORDS:
Subharmonic Screech; Sharp-Edged Orifice; Circular Jets; Thermal Effects
JOURNAL NAME:
Open Journal of Acoustics,
Vol.4 No.1,
March
21,
2014
ABSTRACT: Experiments are performed in choked circular hot and cold
nitrogen jets issuing from a 2.44 cm diameter sharp-edged orifice at a fully
expanded jet Mach number of 1.85 in an effort to investigate the character of screech phenomenon. The stagnation temperature of
the cold and the hot jets are 299 K and 319 K respectively.
The axial distribution of the centerline Mach number was obtained with a pitot tube, while the screech data (frequency and
amplitude) at different axial and radial stations were measured with the aid of
microphones. The fundamental screech
frequency of the hot jet is slightly increased relative to that of the cold
jet. It is concluded that
temperature effects on the screech amplitude are manifested
with regard to the fundamental and the subharmonic even at relatively small temperature range considered.