Large eddy simulation of acoustic waves generated from a hot supersonic jet

Temperature Effects on Convection Speed and Steepened Waves of Temporally Developing Supersonic Jets

“…For M j = 2, in Fig. 9(a,b,d), the inclination angle of the acoustic waves significantly increases with temperature, as noticed in the numerical studies of Nonomura et al [28] and Liu et al [6], for instance. This increase is mainly explained by the higher velocities of jetT2Mj2 and jetT4Mj2 in comparison with jetT1Mj2.…”

“…Any parametric investigation of temperature effects in high-speed jets requires a meticulous control over the flow conditions at the nozzle exit. Indeed, the shape of the velocity profile, the turbulence rates, as well as the state of the nozzle boundary layer can affect noise generation [25][26][27][28]. In supersonic jets, an additional complexity comes from the formation of shock cells in and downstream of the nozzle.…”

“…These shock cells can alter the state of the nozzle boundary layer, modify the location of the mixing layers, and cause variations of the convection speed. To prevent their formation, one possibility is to consider jets exhausting at pressure matched conditions from nozzles that are designed using the method of characteristics as in the study of Nonomura et al [28] for jets at M j = 2. This approach is however costly when different Mach numbers are considered, since it requires the design and the modelling of one nozzle for each Mach number.…”

Links Between Steepened Mach Waves and Coherent Structures for a Supersonic Jet

“…In order to favor the transition of the shear layers from a laminar to a turbulent state, weak random vortical disturbances are added inside the boundary layer. They are Gaussian vortex rings of random phases and amplitudes, as in previous studies of subsonic [37] and supersonic [38,39] jets. Their amplitude is tuned in order to yield maximum turbulence intensities of 3% at the nozzle exit so that the shear layers are initially in a weakly disturbed state.…”

Large eddy simulation of pseudo shock structure in a convergent–long divergent duct

“…Over the past decade, large-eddy simulation (LES) has emerged as a promising alternative for prediction of turbulent flows behavior. This methodology is currently being applied to a wide variety of engineering applications, including combustion [20][21][22][23][24][25][26][27], simulations of the wind turbine [28], acoustics [29][30][31][32], combustion noise [33,34] and several studies of SBLI [35,36]. To illustrate, Koo and Raman [37] applied the dynamic Smagorinsky subgrid model for supersonic inlet of an isolator and they found that this model is suitable for capturing the large-scale features of the unstart process.…”