Browsing by Author "Page, Gary J."

Now showing 1 - 6 of 6
  • No Thumbnail Available
    ItemMetadata only
    Adaptive Wall-Modelled Large Eddy Simulation of Jet Noise in Isolated and Installed Configurations
    (American Institute of Aeronautics and Astronautics (AIAA), 2018-06-24) Angelino, Matteo; Xia, Hao; Page, Gary J.
    The study of jet acoustics is crucial for future aeroengine designs. Although the highbypass ratio of modern turbofans can have a shielding effect on the core jet noise, there is an increased potential of interaction of the jet flow with wing and flap, and its effects on noise need to be thoroughly investigated. Wall-Modelled Large-Eddy Simulation (WMLES) is a powerful method to study the installation effects on jet noise, as it does not have strict near-wall requirements, allowing for a more uniform mesh for better noise propagation and a saving in computational cost. An adaptive wall model is here introduced and validated on channel flow, on the MD-30P/30N high-lift multi-element airfoil, and on the NASA High-Lift Common Research Model (HL-CRM). WMLES simulations, combined with the Ffowcs Williams and Hawkings (FW-H) sound extrapolation method, are performed on turbulent coaxial jets in isolated and installed configurations. Computed flow field and sound spectra present favourable agreement with experimental results, confirming key features of the installation effects on jet noise.
  • Thumbnail Image
    ItemEmbargo
    Far-field Noise Prediction of Round and Serrated Jets with Increasingly Refined Grids
    (22nd AIAA/CEAS Aeroacoustics Conference, 2016-05-27) Angelino, Matteo; Xia, Hao; Moratilla-Vega, Miguel A.; Page, Gary J.
    Turbulent jet large-eddy simulations (LES) are performed at Mach 0.9 and Reynolds number of 106. For subgrid scale stress modeling the sigma-model is used. Solutions are obtained for a baseline axisymmetric (round) nozzle and a serrated (or chevron) nozzle with high bending and penetration, on grids ranging from 5 to 80 million grid points in order to assess the correlation between coarser and finer grid solutions. Computed mean and second-order fluctuating quantities of the turbulent near field compare favorably with measurements. The radiated far-field sound is predicted using the Ffowcs Williams and Hawkings (FW-H) surface integral method. Remarkable agreement of the predicted farfield sound directivity and spectra with measurements is obtained. A preliminary discussion is presented on the correlation and possible combination of multiple spectra from different grids.
  • No Thumbnail Available
    ItemMetadata only
    Inflow Turbulence Impact on Sound Sources of Subsonic Turbulent Jets
    (2019-07-30) Moratilla-Vega, Miguel A.; Xia, Hao; Angelino, Matteo; Chen, Shaun; Page, Gary J.
    The impact of numerically imposed inflow turbulence on the sound sources of turbulent jets is investigated. The sources are defined by the acoustic perturbation equations (APE) with data extracted from compressible large-eddy simulations (LES) of the turbulent jets. Inflow turbulence generated by two commonly used methods is studied. A uniform inlet case without any imposed turbulent fluctuations is also simulated as a reference. The distribution of the noise sources under different inlet conditions is then analysed in the space-frequency domain. The near- and far-field noise are investigated in the last two subsections.
  • No Thumbnail Available
    ItemMetadata only
    Influence of grid resolution on the spectral characteristics of noise radiated from turbulent jets: Sound pressure fields and their decomposition
    (Elsevier, 2019-10-21) Angelino, Matteo; Xia, Hao; Page, Gary J.
    Jet noise remains a key target for aircraft noise reduction in the foreseeable future. While being extremely challenging, the requirement of predicting both low and high frequency noise spectra is increasingly important for design purposes. Novel approaches are needed to overcome the current numerical limitations in capturing the required broad noise spectra. Once sufficiently resolved, the energy contents of the numerically simulated near- and far-field sound pressure have intrinsic correlations among different levels of grid resolution. The present work explores the novel potential of such correlations to broaden the spectral prediction. The noise radiated from high subsonic turbulent jets is investigated using large- eddy simulation. The 3-D filtered compressible Navier-Stokes solutions are obtained for an axisymmetric and a serrated nozzle on successively refined multi-resolution grids, ranging from 5 to 80 million grid points. The radiated far-field sound is computed using the Ffowcs Williams –Hawkings (FW-H) surface integral method. Fourier decomposition for pressure near-field is applied to help identify the location of the sound source regions and the dominant directions of propagation, which provides a more thorough understanding of the effect of the grid resolution on the numerical cut-off frequencies of the far-field spectra. Further analysis of the far-field spectra and of their azimuthal modes confirms that a novel strategy to obtain a broadened overall sound spectrum is possible, at reduced computational cost, from a combination of multiple spectra from successively refined grids.
  • Thumbnail Image
    ItemOpen Access
    Large-eddy simulations of high Reynolds number jets with a suitable subgrid-scale model for solver dependency study
    (11th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements, 2016-09) Angelino, Matteo; Moratilla-Vega, Miguel A.; Xia, Hao; Page, Gary J.
    Large-eddy simulations are performed of a turbulent round jet at Ma = 0.5 and 0.9. The solver dependency is explored on computationally affordable grids of 5 and 20 million grid points, by taking advantage of the consistency of the subgrid-scale sigma-model. Three different solvers are tested. With all three, the computed mean and second-order fluctuating quantities of the turbulent near field compare favorably with measurements, for both Mach numbers and both grids, showing the strength of the sigma-model in adapting to different flow conditions and grid refinements.
  • Thumbnail Image
    ItemOpen Access
    Numerical Investigation of Installed Jet Noise Sensitivity to Lift and Wing/Engine Positioning
    (American Institute of Aeronautics and Astronautics (AIAA), 2019-05-20) Angelino, Matteo; Moratilla-Vega, Miguel A.; Howlett, Alex; Xia, Hao; Page, Gary J.
    As the turbofan engines of modern transport aircraft have increasingly larger bypass ratios, by necessity to avoid longer undercarriage, the engine must be installed closer to the wing. This then has the potential of interaction between the jet flow and a deployed flap. This interaction can be an important noise source when the high-lift systems are deployed, as at approach and take-off. Investigating the parameters that have a strong influence on the installation noise penalty can help in identifying noise reduction measures. In this paper Wall-Modelled Large Eddy Simulations (WMLES), combined with the FfowcsWilliams and Hawkings (FW-H) sound extrapolation method, are performed to reproduce three experimental cases, with the aim of isolating the different contributions of flap angle and trailing-edge/jet-axis distance h. The first case (DOAK), consisting of a single jet installed near a horizontal flat plate, confirms the fundamental mechanisms of jet-surface interaction and jet-surface reflection in the absence of lift. The second case (DLR-F16), with a coaxial jet installed under a high-lift wing, reveals the trailing-edge/jet-axis distance h as the dominant parameter, with a possible influence of the flap angle at low frequencies. The third case (SYMPHONY) is used to study the interaction of a coaxial jet with a full aircraft geometry using Fourier decomposition of the pressure near-field to analyse the effects on sound sources and radiation.