Dual-Pump CARS Measurements in the University of Virginia's Dual-Mode Scramjet: Configuration "C"

Cutler, Andrew D.; Magnotti, Gaetano; Cantu, Luca; Gallo, Emanuela; Danehy, Paul M.; Rockwell, Robert D.; Goyne, Christopher P.; McDaniel, James C.

doi:10.2514/6.2013-335

Cited by 24 publications

(31 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There exists an asymmetry to the shape of the measured velocity contours which is not unexpected as no experimental facility is free from physical asymmetries. Physical asymmetries have been verified by previous SPIV measurements, which showed asymmetric vortices, and CARS measurements that showed an asymmetric in-flow temperature distribution [39,84].…”

Section: Spiv Experimental Results X/h=6 12 82supporting

confidence: 50%

“…further away from the point of fuel injection has been observed by independent CARS measurements of temperature and species (H 2 , N 2 , and O 2 ) concentration on Config. C [37,39]. This could be a factor of the Burke reaction mechanism utilized by the CFD where the combustion efficiency may differ from reality.…”

Section: Discussionmentioning

confidence: 99%

“…Both the nozzle exit flow and fuel injector exit flow were solved previously and used as the inflow to the isolator and fuel injector exit. It should be noted that the CFD simulations included an asymmetric temperature distribution at the entrance to the combustor section which was measured by CARS [37,39]. The mesh in the combustor section of the flowpath contains approximately 33 million cells.…”

Section: Discussionmentioning

confidence: 99%

“…As discussed in Chapter 2, Configuration C has been studied extensively within the NCHCCP through both experiments and computation modeling [37,38,39,40]. The full The combustor section and ramp fuel injector were the same 10° unswept ramp fuel injector that is 12.7 mm wide and 6.35 mm high.…”

Section: Facility and Flow Conditions (Config C Mod )mentioning

confidence: 99%

See 3 more Smart Citations

Characterization of a Dual-Mode Scramjet via Stereoscopic Particle Image Velocimetry

Rice

View full text Add to dashboard Cite

Scramjet propulsion devices have the potential for revolutionizing high-speed atmospheric flight in the future. This includes aerospace planes for space access and high-speed long distance strike vehicles for national defense. Despite over 60 years of research, the high-speed, turbulent, combusting flow field of the engine is not fully understood. In particular, the dual-mode scramjet (DMSJ) is complicated by the ability to operate in different modes of combustion. These modes of combustion are referred to as the ramjet mode of operation, characterized by subsonic combustor inflow, and the scramjet mode of operation, characterized by supersonic combustor inflow. The gap in iii

show abstract

Section: Spiv Experimental Results X/h=6 12 82supporting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Facility and Flow Conditions (Config C Mod )mentioning

confidence: 99%

See 2 more Smart Citations

Characterization of a Dual-Mode Scramjet via Stereoscopic Particle Image Velocimetry

Rice

View full text Add to dashboard Cite

show abstract

“…Measurements of H 2 mole fraction at a plane at x/H = 56.1 show distributions of nearly 0% H 2 for the scram-mode, but approximately 8-10% H 2 for the ram-mode. [58] This indicates that a portion of the H 2 fuel has still not combusted at a plane which is located in the extender section of the UVaSCF. This presence of un-combusted fuel would decrease the combustion efficiency, as is measured by the TDLAT & SPIV combustion efficiency calculation.…”

Section: Combustion Efficiencymentioning

confidence: 99%

Development of Tunable Diode Laser Absorption Tomography and Application to Scramjet Engines

Busa

View full text Add to dashboard Cite

Scramjets are an appealing alternative to traditional rocket engines for many applications such as access to space, long-range strike missile capabilities, and civilian transport. Their advantages over rockets and traditional jet engines include a stationary flow path with no moving parts and higher payload capacity due to their airbreathing operation. A major hindrance to the maturation of scramjet technology is the high-cost and high-risk associated with flight testing. Computational fluid dynamics (CFD) simulations are a promising alternative to flight testing, but much of the complex flow physics present in scramjet engines are not well understood, making the modeling of these high-enthalpy, supersonic, combusting, and three-dimensional flows extremely challenging. Ground testing of scramjet model flow paths allows for experimental measurements of key variables, such as temperature and species number density, in controlled experimental environments. These measurements are guided by preliminary CFD results while also serving to validate the advanced state-of-the-art computational models. This symbiotic relationship between ground test experiments and computational models brings us closer to the realization of operational scramjet technology.Harsh flowfields, such as those found within a scramjet, can present great difficulties for conventional in-stream diagnostics. The high speed, high enthalpy, combusting flowfields make probing the flow very challenging. Optical diagnostics, such as tunable diode laser (TDL) techniques, have an advantage in these harsh flowfields over their mechanical counterparts due to their non-intrusive nature. No hardware comes in contact with the flow itself, and therefore the integrity of the diagnostic is preserved and the flow is undisturbed. Traditional implementations of TDL, such as Tunable Diode Laser Absorption Spectroscopy (TDLAS), are indeed non-intrusive, but are limited by their path-integrated line-of-sight (LOS) nature. The harsh flowfields of a scramjet are highly three-dimensional and thus an optical diagnostic technique capable of producing spatially resolved measurements is required. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive optical technique which combines TDLAS and computed tomography (CT) to produce a 2-D spatially resolved measurement of two key combustion diagnostic properties: temperature and species number density. Several hundred LOS TDLAS measurements are collected for each experiment and are subsequently reconstructed utilizing a tomographic post-processing algorithm. The TDLAT measurement results in highly resolved 2-D temperature and species number density distributions of the flowfield at the probed measurement plane.The work presented herein describes the development of the TDLAT technique, building upon earlier proof-of-concept demonstrations. Application of the TDLAT diagnostic to two scramjet-relevant ground test facilities is presented and the insight gained from the resulting 2-D distributions is discussed. Of gr...

show abstract

Laser‐Based Combustion Diagnostics

Wolfrum

Dreier

Ebert

et al. 2016

Encyclopedia of Analytical Chemistry

View full text Add to dashboard Cite

In laser spectroscopy, the interaction of light emitted from various types of laser sources – tunable or nontunable in their output frequency – with the atomic or molecular species of interest is used to probe the sample through a variety of spectral responses. In order to perform laser spectroscopy, suitable laser sources must be selected, which meet the requirements of the chosen spectroscopic method. This means that the laser has to provide radiation in the wavelength range of interest, has the appropriate emission characteristics (lineshape), and has a suitable energy to perform the measurements. Further requirements are pulse length (milliseconds to femtoseconds or continuous wave), repetition rate, and beam profile. Nowadays, laser radiation can be generated with most of the required parameters necessary for the respective spectroscopic application, either directly or by generating new radiation frequencies by frequency mixing of one or several laser beams in a nonlinear medium (gas, liquid, or solid). As an example, the most direct interrogation technique is absorption of laser radiation (LAS, laser absorption spectroscopy) by suitable spectroscopically allowed transitions in atoms or molecules, which are known from conventional spectroscopic methods. The increase or decrease in the laser radiation transmitted through the sample is then a measure of the amount of substance probed in the sample, which characteristically absorbs at the required wavelength. Laser light‐scattering methods, elastic (Rayleigh scattering (RS)), and inelastic (spontaneous Raman scattering (SRS)) are other techniques to probe the medium. In the first method, which is not species specific, the density of the medium can be interrogated, whereas the second is able to probe all species with Raman‐active vibration–rotation transitions. There are several advantages in using laser spectroscopy instead of conventional spectroscopic techniques using conventional thermal light sources. The spectral brightness of laser beams is many orders of magnitude higher than that of thermal radiation sources, which correspondingly increase the detection sensitivity of laser spectroscopic techniques. In addition, the small linewidth of the emitted radiation dramatically increases the spectral resolution such that minor details of the spectroscopic branch investigated can be resolved. This enables more quantitative interpretations of all parameters influencing the lineshape and line intensity of the probed transition, and as such the physical and chemical environments of the probed species: temperature, pressure, velocity, chemical species, and so on. It makes laser spectroscopic techniques much more selective than conventional methods, which often are not able to separate closely spaced spectral features from different species. A third advantage of laser spectroscopic techniques is connected with the variable pulse duration and repetition frequency of lasers: the very short pulse lengths can be used successfully to probe the sample within time periods that are short compared to any other physical or chemical time development – flow, chemical reaction, pressure changes, and so on. Finally, the small spatial regions that can be probed by focusing diffraction‐limited laser beams makes laser spectroscopic techniques ideally suited for applications where high spatial resolution is required. All these advantages of laser spectroscopy are beneficial when the various techniques are applied as a diagnostic tool in combustion processes: flames constitute a complex interaction of fast chemistry with flow fields and surfaces, and therefore, a detailed understanding of combustion events often needs in situ, species‐specific optical diagnostics with high spatial and temporal resolution. In many recent applications, laser spectroscopy has become a developed technique that can even be performed by nonlaser specialists. However, numerous laser spectroscopic techniques require detailed theoretical knowledge of the spectroscopy underlying the respective technique and the use of sophisticated equipment in order to obtain meaningful results. Future development is aimed toward simplifying experimental set‐ups, data evaluation, and maintenance. This development runs parallel to the breathtaking development in laser technology that continuously increases available wavelength ranges, simplicity of use, pulse power, and repetition rates.

show abstract

Dual-Pump CARS Measurements in the University of Virginia's Dual-Mode Scramjet: Configuration "C"

Cited by 24 publications

References 18 publications

Characterization of a Dual-Mode Scramjet via Stereoscopic Particle Image Velocimetry

Characterization of a Dual-Mode Scramjet via Stereoscopic Particle Image Velocimetry

Development of Tunable Diode Laser Absorption Tomography and Application to Scramjet Engines

Laser‐Based Combustion Diagnostics

Contact Info

Product

Resources

About