High Reynolds number compressible free shear layers were studied experimentally to explore the effects of compressibility on turbulence field. Previous preliminary results reported by authors showed that level and lateral extent fluctuations are reduced as compressibility, which is characterized a convective Mach number, increased. The two numbers used in previous study relatively close, Mc=0.51 0.64, result conclusions not concrete. present with Mc=0.86 strongly support earlier results,...

A high Reynolds number two-dimensional constant pressure compressible shear layer was formed at the trailing edge of an 0.5 mm-thick splitter plate. Convective Mach numbers 0.51 and 0.64 were investigated using a two-component coincident LDV for measurements. For lower convective case, nondimensionalized shear-layer vorticity thickness growth rates over 20 percent higher momentum rate 30 than those case. The results seen to indicate that both small scale large mixing are reduced with...

An experimental investigation was conducted to examine the effect of a pulsed Nd:YAG laser energy addition on shock structures and surface pressure in Mach 3.45 flow past sphere. Two configurations were considered: 1) sphere uniform freestream 2) an Edney IV interaction generated by impingement oblique bow

Experiments were conducted to quantify the temperature and electron number density of a laser spark formed in air. The was created by focusing 180-mJ beam from second harmonic (wavelength 532 nm) pulsed Nd:YAG with 100-mm focal length lens. For early times, between 50 ns 1 μs, images emission have been obtained characterize geometry. Also measured spectra 490 520 nm where 46 N II lines are observed. methodology fitting experimental data modeled deduce is described. initial temporal range,...

While PIV is an established experimental technique for determining a velocity field, quantifying the uncertainty related with this method remains challenging task. The purpose of current work to provide procedure estimating associated time-averaged two-dimensional flow field measurements obtained by means PIV. Four sources are assessed: equipment, particle lag, sampling size, and processing algorithm. An example analysis conducted transverse sonic jet injected into supersonic crossflow. This...

No AccessTechnical NoteExperimental Characterization of a Pulsed Plasma JetTodd M. Reedy, Nachiket V. Kale, J. Craig Dutton and Gregory S. ElliottTodd ReedyMechanical Science Engineering, University Illinois at Urbana–Champaign, Urbana, 61801, KaleMechanical DuttonMechanical 61801 ElliottMechanical 61801Published Online:23 Jul 2013https://doi.org/10.2514/1.J052022SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations About References [1] Knight D., "Survey Aerodynamic Flow...

Abstract Increasingly mechanical engineering departments are beginning to incorporate remotely operated laboratories into their laboratory curriculums. Yet very few studies exist detailing the extent which this new medium for delivery fulfills educational goals of traditional in‐person laboratories. This paper describes a comparison outcomes between and in curriculum. The study carried out 2001 Fall semester was performed using an jet thrust laboratory. illustrate fundamentals compressible...

Molecular filtered Rayleigh scattering (FRS), employing an iodine vapour filter and injection-seeded Nd:YAG laser, was utilized to measure instantaneous average temperature fields in combustion environments. With FRS thermometry, the within cell strongly absorbs background from surfaces particles, while much of Doppler-broadened is not absorbed by transition; gas can then be deduced measured transmission molecular scattering. For demonstration purposes evaluate accuracy technique, we...

Laser energy deposition in quiescent air has been studied experimentally and numerically. The study is focused on the gasdynamic effects of laser spot e ow structure. A Gaussian proe le for initial temperature distribution proposed to model assuming density initially uniform. ltered Rayleigh scattering technique used obtaining experimental results. These consisted visualization blast wave, simultaneous pressure, temperature, velocity measurements. Good agreement achieved between numerical...

Space-time correlations were used to study compressibility effects on large structures in mixing layers. Two high Reynolds number layers with Mc=0.51 (case 1) and 0.86 2) studied. The results indicate that the case 1 are similar those subsonic case, but less organized. 2 highly three dimensional, a good spatial poor temporal organization. streamwise showed decay rate 4 5 times greater for relative 1. While spanwise trends incompressible layers, behavior of was very different. pressure...

Single- and double-pulsed visualizations were employed to study the characteristics evolution of large-scale structures in compressible mixing layers with convective Mach numbers (Mc) 0.51 0.86. Instantaneous images spatial correlations based on large ensembles show that which span entire layer thickness are a more dominant feature at Mc=0.51 than Mc=0.86. Double-pulsed developing region structures’ formation proceed as roll-up wavy region, agreement Kelvin–Helmholtz picture structure...

One of the principal challenges in prediction and design low-noise nozzles is accounting for near-nozzle turbulent mixing layers at high Reynolds numbers engineering conditions. Even large-eddy simulation a challenge because locally largest scales are so small relative to nozzle diameter. Model-scale experiments likewise typically have relatively thick shear layers, which potentially hampers their applicability high-Reynolds-number design. To quantify sensitivity far-field sound...

Filtered Rayleigh scattering-based flow visualizations of compressible mixing layers are reported. The lower compressibility case (Mc = 0.51) displays well-defined roller-type spanwise structures and streamwise streaks. the high 0.86) more 3D oblique.

The compressible shear layer over a 3:1 rectangular cavity was investigated using schlieren photography and planer laser imaging at freestream Mach numbers of 1.8, 2.1, 2.8, 3.5. purpose this investigation to study the characteristics structures their convective velocity number range. Schlieren images show leading- trailing-edge shock waves, as well waves emanating from layer, which became less prevalent increased. Streamwise planar sheet lighting indicate existence organized roller-type...

An experimental study was conducted to investigate the pressure fluctuations on entire sidewall of a rectangular cavity with an 5.67 using fast-response pressure-sensitive paint. Additionally, performance four different passive flow-control devices quantified. Experiments were in Trisonic Gasdynamics Facility at Air Force Research Laboratory Mach 0.7 and 1.5. The frequency spectrum (including Rossiter tones) sound levels obtained from paint measurements are validated against data taken...

Characterization of the inductively coupled plasma (ICP) torch at Plasmatron X facility developed by Center for Hypersonics & Entry Systems Studies (CHESS) was performed means optical emission spectroscopy (OES). OES provides a noninvasive method identifying both atomic and molecular species within jet without physically perturbing flow. Additionally, experimental spectra can be compared to simulated provide estimates gas temperature. In this work, we present preliminary results...

View Video Presentation: https://doi.org/10.2514/6.2023-1338.vid Inductively coupled plasma wind tunnels accurately replicate the harsh conditions that hypersonic vehicles experience during atmospheric reentry phase. With ability to reproduce aerothermal heating and chemistry of flight, phenomena such as gas-surface interactions, heat shield ablation response, aero-optics, non-equilibrium can be investigated in a pristine flexible test environment. This paper describes new Plasmatron X...