Numerical Investigation of Indirect Noise Generation by Accelerated Vorticity

Ullrich, Wolfram C.; Bake, Friedrich; Kings, Nancy; Sattelmayer, Thomas

doi:10.2514/6.2015-2382

Cited by 8 publications

(6 citation statements)

References 23 publications

(18 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the effects of turbulent mixing or flow separation on indirect combustion noise as described by Howe 19 can also be studied further within this specific numerical context. All of these effects have not been studied in previous EWG works, which are based on the coupling of RANS simulations with computational aeroacoustic (CAA) methodologies, 20,21 unsteady RANS simulations, 12,13 Euler simulations, and even analytical modeling. 9,11,22 To reach the need for higher-fidelity flow predictions, Large Eddy Simulation (LES) seems to be a first good candidate to simulate the high Reynolds number EWG subsonic test case, and provide further insight into the physical phenomena of indirect combustion noise generation and transmission.…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy-simulation prediction of indirect combustion noise in the entropy wave generator experiment

Moreau

Becerril

Gicquel

2017

International Journal of Spray and Combustion Dynamics

View full text Add to dashboard Cite

Compact and non-compact analytical solutions of the subsonic operating point of the entropy wave generator experiment are compared with detailed numerical results obtained by large Eddy simulations. Two energy deposition methods are presented to account for the experimental ignition sequence and geometry: a single-block deposition as previously used and a delayed deposition that reproduces the experimental protocle closely. The unknown inlet acoustic reflection coefficient is assumed to be fully reflective to be more physically consistent with the actual experimental setup. The time delay between the activation of the heating modules must be considered to retrieve the temperature signal measured at the vibrometer and pressure signals at the microphones. Moreover, pressure signals extracted from the large Eddy simulations in the outlet duct using the delayed ignition model clearly reproduce the experimental signals better than the analytical models. An additional simulation with actual temperature fluctuations directly injected at the inlet of the computational domain clearly shows that the pressure fluctuations produced by the acceleration of the hot slug yields indirect noise almost entirely. Finally, the entropy spot is shown to be distorted when convecting through the turbulent flow in the entropy wave generator nozzle. Its amplitude decreases and its shape is dispersed, but hardly any dissipation occurs. The distortion appears to be negligible through the nozzle and become important only when convected over a long distance in the downstream duct. As the dominant frequencies of the entropy wave generator entropy forcing are very low, the effects of dispersion by the mean flow are however weak.

show abstract

Section: Introductionmentioning

confidence: 99%

Large-Eddy-simulation prediction of indirect combustion noise in the entropy wave generator experiment

Moreau

Becerril

Gicquel

2017

International Journal of Spray and Combustion Dynamics

View full text Add to dashboard Cite

show abstract

“…numerical simulations [17][18][19][20], and experiments [21][22][23][24] aiming to evaluate and release the restrictive assumptions made by Marble and Candle [12]. While these studies advanced the theory considerably, most of them neglected the evolution of entropy waves during their convection by the mean flow.…”

Section: Nomenclaturementioning

confidence: 99%

A comparative analysis of the evolution of compositional and entropy waves in turbulent channel flows

et al. 2022

View full text Add to dashboard Cite

Indirect combustion noise, as an important source of noise in gas turbines, was traditionally attributed solely to entropy waves. In recent years, compositional waves were introduced as another contributor to indirect combustion noise. Nonetheless, unlike that of entropy waves, the annihilation of compositional waves by the mean flow has remained largely unexplored. Hence, the current numerical study analyses the spatiotemporal evolution of different components of compositional waves and compares them with the decay of entropy waves. A convecting wave, including a mixture of combustion products at elevated temperature, is introduced at the inlet of a simple channel. This allows simultaneous analysis of entropy and compositional waves. The passage of these along the channel is modeled using a large eddy simulation and the annihilation of the waves' components is examined in the frequency domain. It is shown that the turbulence level of the mean flow and convective heat transfer on the walls can both result in a considerable wave deterioration.However, the effects of heat losses from the channel walls are found to be stronger than that of turbulence intensity. Importantly, as the wave is convected, the chemical potential function remains coherent for most of the channel length and deterioration of the compositional wave majorly ensues from the mixture fraction gradient. The results indicate that, overall, the compositional sources feature 10% to 20% more dissipation in comparison with the entropic sources. Therefore, compositional waves are less likely to survive the flow and generate noise.

show abstract

“…Vortex-driven indirect-combustion noise is known to play a major role in the establishment of self-sustained pressure pulsations in large Solid Rocket Motors [1][2][3][4], and is believed to be an indirect-combustion noise source in aircraft engines [5,6]. Vortex-driven indirect-combustion noise will partly be radiated outward, thus contributing to environmental noise.…”

Section: Introductionmentioning

confidence: 99%

“…To the best of the authors' knowledge, in the literature there is only one attempt at model-based analysis of the above mentioned experiments, that by Ullrich et al [6] who reported simulations which used a hybrid CFD/CAA model. Echoing Kings' and Bake's hypothesis, Ullrich's et al [6] modeling approach fundamentally supposed that sound production in the experiments was due to acceleration of vorticity waves through the nozzle.…”

Section: Introductionmentioning

confidence: 99%

Sound Production due to Swirl-Nozzle Interaction: Model-Based Analysis of Experiments

Hirschberg

Hulshoff

Bake

2020

Aiaa Aviation 2020 Forum

Self Cite

View full text Add to dashboard Cite

Indirect noise due to the interaction of flow inhomogeneities with a choked nozzle is as an important cause of combustion instability in solid rocket motors and is believed to be important in aircraft engines. A previously published experiment demonstrated that interaction of the nozzle with time-dependent axial swirl can also be a source of sound. This axial swirl was generated by intermittent circumferential mass injection upstream from a choked nozzle in a so-called Vortex Wave Generator. The present work discusses the impact of swirl-nozzle interaction in this experiment on the acoustic waves detected downstream of the nozzle. The main source of sound appears to be the reduction in mass flux through the choked nozzle, which depends quadratically on the swirl number. This effect is quantitatively predicted by a quasi-steady and quasi-cylindrical analytical model. The model, combined with empirical data for the decay of axial swirl in pipe flows, predicts the observed influence of the distance between the Vortex Wave Generator and the nozzle. The findings presented here contradict the hypothesis found in the literature, which presumes that sound production in the abovementioned experiment is due to the acceleration of vorticity waves through the nozzle.

show abstract

Numerical Investigation of Indirect Noise Generation by Accelerated Vorticity

Cited by 8 publications

References 23 publications

Large-Eddy-simulation prediction of indirect combustion noise in the entropy wave generator experiment

Large-Eddy-simulation prediction of indirect combustion noise in the entropy wave generator experiment

A comparative analysis of the evolution of compositional and entropy waves in turbulent channel flows

Sound Production due to Swirl-Nozzle Interaction: Model-Based Analysis of Experiments

Contact Info

Product

Resources

About