Experimental investigations of sound reflection from hot and subsonic flow duct termination

Abstract The knowledge of the reflection properties of open end jet ducts is important for different applications, where the flow and high temperature conditions are involved and add complexity to the problem. In this paper, the magnitude of the reflection coefficients together with the respective end-corrections is experimentally determined for hot flow duct openings. A Mach number range up to 0.3 for cold jets and up to 0.12 for a jet temperature of 200 °C is treated. The experimental results are compared with the numerical model proposed by Munt (Acoustic transmission properties of a jet duct with subsonic jet flow: 1. The cold jet reflection coefficient, Journal of Sound and Vibration 142 (1990) 413–436) and a good correlation in plane-wave region is demonstrated. To reduce experimental uncertainty, the sound reflection properties at the duct opening are obtained by using an overdetermined two-microphone technique with the implementation of a three pressure transducer array. By introducing a modified multistep version of the stepped sine excitation, the accuracy of data acquisition process is improved without compromising the measurement time.

[1]  M. S. Howe.  The damping of sound by wall turbulent shear layers , 1995 .

[2]  D. A. Blaser,et al.  Transfer function method of measuring in-duct acoustic properties. I - Theory. II - Experiment , 1980 .

[3]  J. Ih,et al.  ON THE MULTIPLE MICROPHONE METHOD FOR MEASURING IN-DUCT ACOUSTIC PROPERTIES IN THE PRESENCE OF MEAN FLOW , 1998 .

[4]  L. van Wijngaarden,et al.  Flow in the exit of open pipes during acoustic resonance , 1980, Journal of Fluid Mechanics.

[5]  A Avraham Hirschberg,et al.  Damping and reflection coefficient measurements for an open pipe at low Mach and low Helmholtz numbers , 1993, Journal of Fluid Mechanics.

[6]  R. Munt.  The interaction of sound with a subsonic jet issuing from a semi-infinite cylindrical pipe , 1977, Journal of Fluid Mechanics.

[7]  Sw Sjoerd Rienstra,et al.  A small strouhal number analysis for acoustic wave - jet flow - pipe interaction , 1980 .

[8]  Mats Åbom,et al.  Error analysis of two‐microphone measurements in ducts with flow , 1988 .

[9]  Mats Åbom,et al.  Investigation of damping and radiation using full plane wave decomposition in ducts , 2006 .

[10]  Gary P. Scavone,et al.  Sound reflection at the open end of axisymmetric ducts issuing a subsonic mean flow: A numerical study , 2009 .

[11]  S. Candel,et al.  Acoustic transmission and reflection by a shear discontinuity separating hot and cold regions , 1972 .

[12]  R. Munt,et al.  Acoustic transmission properties of a jet pipe with subsonic jet flow: I. The cold jet reflection coefficient , 1990 .

[13]  Uno Ingard,et al.  Upstream and Downstream Sound Radiation into a Moving Fluid , 1973 .

[14]  D. W. Bechert,et al.  Sound absorption caused by vorticity shedding, demonstrated with a jet flow☆ , 1980 .

[15]  A. M. Cargill,et al.  Low frequency acoustic radiation from a jet pipe—a second order theory , 1982 .

[16]  H. Ribner.  Reflection, Transmission, and Amplification of Sound by a Moving Medium , 1957 .

[17]  J. Laufer,et al.  The Structure of Turbulence in Fully Developed Pipe Flow , 1953 .

[18]  J. Miles.  On the Reflection of Sound at an Interface of Relative Motion , 1957 .

[19]  G. F. Carrier.  Sound transmission from a tube with flow , 1956 .

[20]  E. Dokumaci.  A note on transmission of sound in a wide pipe with mean flow and viscothermal attenuation , 1997 .

[21]  J. Schwinger,et al.  On the Radiation of Sound from an Unflanged Circular Pipe , 1948 .

[22]  Hans Rämmal,et al.  Sound reflection at an open end of a circular duct exhausting hot gas , 2008 .

[23]  H. Schlichting.  Boundary Layer Theory , 1955 .

[24]  Hsue-shen Tsien,et al.  The transfer functions of rocket nozzles , 1952 .

[25]  Peter Freymuth,et al.  On transition in a separated laminar boundary layer , 1966, Journal of Fluid Mechanics.