Mach Number Influence on Vortex Breakdown in Compressible, Subsonic Swirling Nozzle-Jet Flows

A global analysis of steady states of inviscid compressible subsonic swirling flows in a finite-length straight circular pipe is developed. A nonlinear partial differential equation for the solution of the flow stream function is derived in terms of the inlet flow specific total enthalpy, specific entropy and circulation functions. The equation reflects the complicated thermo–physical interactions in the flows. Several types of solutions of the resulting nonlinear ordinary differential equation for the columnar case together with a flow force condition describe the outlet state of the flow in the pipe. These solutions are used to form the bifurcation diagram of steady compressible flows with swirl as the inlet swirl level is increased at a fixed inlet Mach number. The approach is applied to two profiles of inlet flows, solid-body rotation and the Lamb–Oseen vortex, both with a uniform axial velocity and temperature. The computed results provide for each inlet flow profile theoretical predictions of the critical swirl levels for the appearance of vortex breakdown states as a function of the inlet Mach number, suggesting that the results are robust for a variety of inlet swirling flows. The analysis sheds light on the dynamics of compressible flows with swirl and vortex breakdown, and shows the delay in the appearance of breakdown with increase of the inlet axial flow Mach number in the subsonic range of operation. The present theory is limited to axisymmetric dynamics of swirling flows in pipes where the wall boundary layer is thin and attached and does not interact with the flow in the bulk.

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Investigation of Vortex Breakdown and Scalar Mixing in Swirling Turbulent Jet Flows using Unified LES-RANS Models

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition ◽

10.2514/6.2011-768 ◽

2011 ◽

Cited By ~ 2

Author(s):

Harish Gopalan ◽

Celestin Zemtsop ◽

Stefan Heinz ◽

Michael Stoellinger

Keyword(s):

Vortex Breakdown ◽

Turbulent Jet ◽

Jet Flows ◽

Scalar Mixing ◽

Rans Models

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Toward a Vortex Breakdown Condition for Swirling Annular Jets

Journal of Fluids Engineering ◽

10.1115/1.2821988 ◽

1999 ◽

Vol 121 (1) ◽

pp. 102-105 ◽

Cited By ~ 2

Author(s):

C. F. Stein

Keyword(s):

Channel Flow ◽

Vortex Breakdown ◽

Jet Flows ◽

Theoretical Discussion ◽

Cfd Simulations ◽

Definite Answer ◽

Significant Phenomenon ◽

The Common ◽

Underlying Mechanisms ◽

Annular Jets

Vortex breakdown is a significant phenomenon in science and technology. In spite of extensive research, the question of the underlying mechanisms for vortex breakdown still lacks a definite answer. The uncertainty of the governing principles for vortex breakdown is revealed by the common use of a variety of different parameters to describe the degree of swirl. In this paper, a theoretical discussion on the suitability of three kinds parameters was conducted, and it was found that one appears to be the natural one if the flow is primarily a swirling channel flow, but if the jet character of the flow is dominant, another one appears to be the most suitable. CFD simulations were performed for a channel with an annular inlet considerably smaller than the channel width. For this case the jet character of the flow should predominate and it was found that the parameter, which theoretically appeared to be best suited for jet flows, indeed was less dependent of the detailed inflow geometry than the others.

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Stochastic-Based RANS-LES Simulations of Swirling Turbulent Jet Flows

International Journal of Nonlinear Sciences and Numerical Simulation ◽

10.1515/ijnsns-2016-0069 ◽

2017 ◽

Vol 18 (5) ◽

pp. 351-369 ◽

Cited By ~ 2

Author(s):

Michael K. Stoellinger ◽

Stefan Heinz ◽

Celestin P. Zemtsop ◽

Harish Gopalan ◽

Reza Mokhtarpoor

Keyword(s):

Vortex Breakdown ◽

Hybrid Methods ◽

Turbulent Jet ◽

Jet Flows ◽

Flow Simulations ◽

Swirling Jet ◽

Les Model ◽

Sound Theoretical Basis ◽

Better Than ◽

Good Agreement

AbstractMany turbulent flow simulations require the use of hybrid methods because LES methods are computationally too expensive and RANS methods are not sufficiently accurate. We consider a recently suggested hybrid RANS-LES model that has a sound theoretical basis: it is systematically derived from a realizable stochastic turbulence model. The model is applied to turbulent swirling and nonswirling jet flow simulations. The results are shown to be in a very good agreement with available experimental data of nonswirling and mildly swirling jet flows. Compared to commonly applied other hybrid RANS-LES methods, our RANS-LES model does not seem to suffer from the ’modeled-stress depletion’ problem that is observed in DES and IDDES simulations of nonswirling jet flows, and it performs better than segregated RANS-LES models. The results presented contribute to a better physical understanding of swirling jet flows through an explanation of conditions for the onset and the mechanism of vortex breakdown.

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Mach Number Effects on Vortex Breakdown in Subsonic Flow over a Delta Wing

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition ◽

10.2514/6.2011-677 ◽

2011 ◽

Author(s):

Hiroaki Fukumoto ◽

Yoshihiro Ishikawa ◽

Taku Nonomura ◽

Kozo Fujii

Keyword(s):

Mach Number ◽

Subsonic Flow ◽

Vortex Breakdown ◽

Delta Wing

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Impact of rotating and fixed nozzles on vortex breakdown in compressible swirling jet flows

European Journal of Mechanics - B/Fluids ◽

10.1016/j.euromechflu.2016.01.006 ◽

2016 ◽

Vol 57 ◽

pp. 214-230 ◽

Cited By ~ 3

Author(s):

T. Luginsland ◽

F. Gallaire ◽

L. Kleiser

Keyword(s):

Vortex Breakdown ◽

Jet Flows ◽

Swirling Jet

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On the Mach Number Invariance of Gas Jets Expanding Into Hot or Cold Environments

Journal of Heat Transfer ◽

10.1115/1.3222735 ◽

2009 ◽

Vol 132 (3) ◽

Cited By ~ 2

Author(s):

R. Sambasivam ◽

F. Durst

Keyword(s):

Mach Number ◽

Practical Importance ◽

Experimental Studies ◽

Basic Oxygen Furnace ◽

Jet Flows ◽

Basic Oxygen ◽

Ambient Temperatures ◽

Cold Environments ◽

Gas Jets ◽

Significant Temperature

Gas jet flows expanding into a space containing the same medium but at a significant temperature difference are of concern in many fields of engineering. One such example is the expansion of supersonic oxygen jets in the basic oxygen furnace (BOF) steelmaking process. While studying the characteristics of such gas jets, an interesting invariance of the local Mach number with the change in the surrounding temperature was found. The velocity and temperature of the jet at any given location increased with the increasing ambient temperature. However, the local Mach number remained the same for all ambient temperatures. This interesting result was further studied since there is no mention of it in any published literature. The reasons for these characteristics of the jet are analyzed in this paper. It is stressed that this finding is of practical importance and can be used in experimental studies of submerged gas jets expanding into environments with different ambient temperatures.

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