Self-excited compressible flow in a pipe–collar nozzle

Selerowicz, W. C.; Szumowski, A. P.; Meier, G. E. A.

doi:10.1017/s0022112091002781

Cited by 9 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the closely related Whistler nozzle configuration a similar behaviour was found by Hirschberg et al (1988), who explained the sound production in terms of vortex sound. Like in the 'Whistler nozzle' studied by Selerowicz, Szumowski & Meier (1991) and Hirschberg et al (1988), the horn presents significant acoustical energy production when the travel time of vortices across the horn matches a number of acoustic oscillation periods. The acoustical energy production at Sr, x na/r corresponds to the first hydrodynamic mode.…”

mentioning

confidence: 98%

Damping and reflection coefficient measurements for an open pipe at low Mach and low Helmholtz numbers

et al. 1993

View full text Add to dashboard Cite

The propagation of plane acoustic waves in smooth pipes and their reflection at open pipe terminations have been studied experimentally. The accuracy of the measurements is determined by comparison of experimental data with results of linear theory for the propagation of acoustic waves in a pipe with a quiescent fluid. The damping and the reflection at an unflanged pipe termination are compared.In the presence of a fully developed turbulent mean flow the measurements of the damping confirm the results of Ronneberger & Ahrens (1977). In the high-frequency limit the quasi-laminar theory of Ronneberger (1975) predicts accurately the convective effects on the damping of acoustic waves. For low frequencies a simple theory combining the rigid-plate model of Ronneberger & Ahrens (1977) with the theoretical approach of Howe (1984) yields a fair prediction of the influence of turbulence on the shear stress. The finite response time of the turbulence near the wall to the acoustic perturbations has to be taken into account in order to explain the experimental data. The model yields a quasi-stationary limit of the damping which does not take into account the fundamental difference between the viscous and thermal dissipation observed for low frequencies.Measurements of the nonlinear behaviour of the reflection properties for unflanged pipe terminations with thin and thick walls in the absence of a mean flow confirm the theory of Disselhorst & van Wijngaarden (1980), for the low-frequency limit. It appears however that a two-dimensional theory such as proposed by Disselhorst & van Wijngaarden (1980) for the high-frequency limit underestimates the acoustical energy absorption by vortex shedding by a factor 2.5.The measured influence of wall thickness on the reflection properties of an open pipe end confirms the linear theory of Ando (1969). In the presence of a mean flow the end correction δ of an unflanged pipe end varies from the value at the high-Strouhal-number limit of δ/a = 0.61, with a the pipe radius, which is close to the value in the absence of a mean flow given by Levine & Schwinger (1948) of δ/a = 0.6133, to a value of δ/a = 0.19 in the low-Strouhal-number limit which is close to the value predicted by Rienstra (1983) of δ/a = 0.26.The pressure reflection coefficient is found to agree with the theoretical predictions by Munt (1977, 1990) and Cargill (1982b) in which a full Kutta condition is included. The accuracy of the theory is fascinating in view of the dramatic simplifications introduced in the theory. For a thick-walled pipe end and a pipe terminated by a horn the end correction behaviour is similar. It is surprising that the nonlinear behaviour at low frequencies and high acoustic amplitudes in the absence of mean flow does not influence the end correction significantly.The aero-acoustic behaviour of the pipe end is dramatially influenced by the presence of a horn. In the presence of a mean flow the horn is a source of sound for a critical range of the Strouhal number.The high accuracy of the experimental data suggests that acoustic measurements can be used for a systematic study of turbulence in unsteady flow and of unsteady flow separation.

show abstract

mentioning

confidence: 98%

Damping and reflection coefficient measurements for an open pipe at low Mach and low Helmholtz numbers

et al. 1993

View full text Add to dashboard Cite

show abstract

“…The excited modes depend on the jet velocity and the dimensions of the collar (Selerowicz et al 1991). The excited modes depend on the jet velocity and the dimensions of the collar (Selerowicz et al 1991).…”

Section: Mixing Enhancementmentioning

confidence: 98%

Mixing Enhancement in Supersonic Free Shear Flows

Gutmark¹,

Schadow²,

Yu³

1995

Annu. Rev. Fluid Mech.

285

View full text Add to dashboard Cite

“…4 Hasan and Hussain5 found this type of flow could be very useful for their studies of large-scale coherent structures in circular jets, because of the ease with which controlled perturbation may be induced in the flow. The pipe-collar flow is generated by a simple geometry consisting of a pipe with a collar at its exit so that the diameter of the duct is suddenly increased.…”

Section: Self-excited Jet Flowmentioning

confidence: 99%

<title>Tomographic holographic interferometric study of self-excited compressible jet flows</title>

Timmerman

Watt

1997

SPIE Proceedings

View full text Add to dashboard Cite

The study of a self-excited compressiblejet using single and double-pulsed, phase-shifted interferometry in conjunction with a 9 beam tomographic illumination system is described. A plane wave holographic interferometer using a pulsed ruby laser has been adapted to provide multiple illumination directions of a volume that is approximately 4 centimeters on a side. This set-up is being used to study the transient behaviour of compressible jets and may be operated using double-exposure holographic interferometry to study the instantaneous behaviour of the flow; alternatively, the system may be operated in a double-pulse mode to study the fluctuations in the flow. The tomographic reconstructions are made using a Fourier-Bessel expansion. To illustrate the performance of the system, an oscillating pipe-collar nozzle flow producing a wavy flow pattern was studied. The instantaneous measurements show the flow to be oscillating in one plane, whereas from the differential results it is found that this plane is rotating during the oscillation period.

show abstract

Self-excited compressible flow in a pipe–collar nozzle

Cited by 9 publications

References 8 publications

Damping and reflection coefficient measurements for an open pipe at low Mach and low Helmholtz numbers

Damping and reflection coefficient measurements for an open pipe at low Mach and low Helmholtz numbers

Mixing Enhancement in Supersonic Free Shear Flows

<title>Tomographic holographic interferometric study of self-excited compressible jet flows</title>

Contact Info

Product

Resources

About