Large Eddy Simulation of Fluidic Injection into a Supersonic Convergent-Divergent Duct

Semlitsch, Bernhard; Mihăescu, Mihai; Fuchs, László

doi:10.1007/978-3-319-14448-1_37

Cited by 3 publications

(2 citation statements)

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“…The compressible flow solver 16 has already been used in previous studies by Semlitsch et al 17,18 to perform Large Eddy Simulations of round non-ideally expanded supersonic jets. The simulations are carried out by using a finite volume method and by solving unsteady compressible Navier-Stokes equations on structured meshes.…”

Section: Iia Numerical Methodsmentioning

confidence: 99%

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Gojon

Baier

Gutmark

et al. 2017

55th AIAA Aerospace Sciences Meeting

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In the first part of the paper, a modified artificial dissipation mechanism permitting to perform Large-Eddy Simulations of highly compressible flows is proposed. This dissipation mechanism is evaluated using one linear 2-D test case and two non-linear 2-D test cases. In the second part, the flow and acoustic near-field of rectangular supersonic jets are explored using compressible LES based on this modified artificial dissipation mechanism. At the exit of a converging diverging rectangular nozzle of aspect ratio 2 and of design Mach number 1.5, the jets are overexpanded. Four simulations with four different temperature ratios ranging from 1 to 3 are performed in order to characterize the effect of the temperature on the aerodynamic and aeroacoustic fields of the jets. The geometry of the nozzle and the exit conditions are chosen in order to match those in the experimental study conducted at the University of Cincinnati. It is shown that the total number of cells in the shock cell structure decreases with the increase of the temperature ratio. However, the temperature does not influence the size of the first shock cell and the linear decrease of the shock cell size in the downstream direction. The Overall Sound Pressure Levels are then plotted along the minor and major axis. It is seen that the intensity of the screech feedback mechanism increases with the Temperature Ratio. Moreover, for JetTR25 and JetTR3, the strong flapping motion of the jet along the minor axis due to the screech feedback mechanism seems to yield to an asymmetric organization of the Mach wave radiation. The convection velocity of the turbulent structures in the jet shear layers along the minor axis is then studied. Once normalized by the jet exit velocity, the convection velocity is shown to decrease with the jet temperature ratio. In the last part of the paper, the near-and farfield acoustic are studied. In the near-field, screech tones which frequencies are consistent with both experimental data and a theoretical model are observed. In the far-field, four acoustic components typical of non-ideally supersonic jets are observed, namely the screech noise, the broadband shock-associated noise, the mixing noise and the Mach wave noise. Their directivities and frequencies are in agreement with experimental results and models.

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Section: Iia Numerical Methodsmentioning

confidence: 99%

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Gojon

Baier

Gutmark

et al. 2017

55th AIAA Aerospace Sciences Meeting

View full text Add to dashboard Cite

show abstract

“…The compressible flow solver [21] has already been used in previous studies by Semlitsch et al [22,23] to perform Large Eddy Simulations of round non-ideally expanded supersonic jets. The simulations are carried out by using a finite volume method and by solving the unsteady compressible Navier-Stokes equations on structured meshes.…”

Section: The Flow Solvermentioning

confidence: 99%

Antisymmetric Oscillation Modes in Rectangular Screeching Jets

2019

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In this paper, the origin and the properties of the oscillation modes in screeching nonideally expanded rectangular jets are investigated using compressible implicit LES of rectangular supersonic jets. At the exit of a converging diverging rectangular nozzle of aspect ratio 2 and of design Mach number 1.5, the jets are under-and over-expanded. Seven simulations with four different temperature ratios ranging from 1 to 3 and two different nozzle pressure ratios are performed. The geometry of the nozzle and the exit conditions are chosen such that to match the experimental study conducted at the University of Cincinnati. First, the over-expanded jets are studied. It is shown that the total number of shock cells decreases with increased temperature ratio. However, the temperature does not influence the size of the first shock cell and the linear decrease of the shock cell size in the downstream direction. The spreading of the jet is observed to be higher along the minor axis plane than along the major axis plane. The intensity of the screech noise increases with the temperature ratio in the present study although the opposite is observed in the experiments. Moreover, for jet temperature ratios of 2.5 and 3, the strong flapping motion of the jet along the minor axis plane due to the screech feedback mechanism yields to an antisymmetric organization of the Mach wave radiation. Thereafter, the near-and far-field acoustic are studied. In the near-field, screech tones are captured, whose frequencies are consistent with both experimental data and theoretical models. In the far-field, four acoustic components typical of non-ideally expanded supersonic jets are observed, namely the screech noise, the broadband shock-associated noise, the mixing noise and the Mach wave noise. Their directivities and frequencies are in agreement with experimental results and models. The mechanism of the screech noise generation is studied by using a Fourier decomposition of the pressure field. For the four over-expanded jets, a flapping motion along the diagonal or along the minor axis plane of the jet is noted. Finally, the hypothesis that the acoustic waves completing the feedback loop in these jets are linked to the upstreampropagating acoustic wave modes of the equivalent ideally expanded jets is tested. Using a jet vortex sheet model to describe the dispersion relations of these modes, it is found that this hypothesis allows us to explain the antisymmetric jet oscillation observed at the screech frequencies. Based on frequency-wavenumber decomposition of the pressure fluctuations in the jets, it is shown that at the screech frequencies, acoustic waves propagating in the upstream direction at the ambient speed of sound exist also in the jet flow, additionally

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Thrust Augmentation of Micro-Resistojets by Steady Micro-Jet Blowing into Planar Micro-Nozzle

2021

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The present work investigates the impact of steady micro-jet blowing on the performance of a planar micro-nozzle designed for both liquid micro-thrusters and nitrogen cold-gas micro-resistojets. Two micro-injectors have been placed into the divergent region along the sidewalls, injecting a secondary flow of propellant perpendicularly to the wall where they have been located. The micro-jet actuator configuration is characterized by the dimensionless momentum coefficient cμ. The best performance improvement is retrieved at the maximum cμ for both water vapor (Δ%T,jet = +22.6% and Δ%Isp,Tjet = +2.9% at cμ = 0.168) and nitrogen gaseous flows (Δ%T,jet = +36.1% and Δ%Isp,Tjet = +9.1% at cμ = 0.297). The fields of the Mach number and the Schlieren computations, in combination with the streamline visualization, reveal the formation of two vortical structures in the proximity of secondary jets, which energize the core flow and enhance the expansion process downstream secondary jets. The compressible momentum thickness along the width-wise direction θxy in presence of secondary injection reduces as a function of cμ. In particular, it becomes smaller than the one computed for the baseline configuration at cμ > 0.1, decreasing up to about and -57% for the water vapor flow at cμ = 0.168, and -64% for the nitrogen gaseous flow at cμ = 0.297.

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Large Eddy Simulation of Fluidic Injection into a Supersonic Convergent-Divergent Duct

Abstract:
QC 20140825

Cited by 3 publications

References 1 publication

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Antisymmetric Oscillation Modes in Rectangular Screeching Jets

Thrust Augmentation of Micro-Resistojets by Steady Micro-Jet Blowing into Planar Micro-Nozzle

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Large Eddy Simulation of Fluidic Injection into a Supersonic Convergent-Divergent Duct

Abstract: QC 20140825

Cited by 3 publications

References 1 publication

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet

Antisymmetric Oscillation Modes in Rectangular Screeching Jets

Thrust Augmentation of Micro-Resistojets by Steady Micro-Jet Blowing into Planar Micro-Nozzle

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Abstract:
QC 20140825