Taitech Inc.

Beavercreek, OH, United States

Taitech Inc.

Beavercreek, OH, United States
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Peltier S.J.,Air Force Research Lab | Lin K.-C.,Taitech Inc. | Carter C.D.,Air Force Research Lab | Kastengren A.L.,Argonne National Laboratory
Experiments in Fluids | Year: 2017

In the present study, the internal flowfield of aerated-liquid fuel injectors is examined through X-ray radiography and X-ray fluorescence. An inside–out injector, consisting of a perforated aerating tube within an annular liquid stream, sprays into a quiescent environment at a fixed mass flow rate of water and nitrogen gas. The liquid is doped with bromine (in the form of NaBr) to create an X-ray fluorescence signal. This allows for reasonable absorption and fluorescence signals, and one or both diagnostics can be used to track the liquid distribution. The injector housing is fabricated from beryllium (Be), which allows the internal flowfield to be examined (as Be has relatively low X-ray attenuation coefficient). Two injector geometries are compared, illustrating the effects of aerating orifice size and location on the flow evolution. Time-averaged equivalent pathlength and line-of-sight averaged density ρ(y) reveal the formation of the two-phase mixture, showing that the liquid film thickness along the injector walls is a function of the aerating tube geometry, though only upstream of the nozzle. These differences in gas and liquid distribution (between injectors with different aerating tube designs) are suppressed as the mixture traverses the nozzle contraction. The averaged liquid velocity (computed from the density and liquid mass flow rate) reveals a similar trend. This suggests that at least for the current configurations, the plume width, liquid mass distribution, and averaged liquid velocity for the time-averaged external spray are insensitive to the aerating tube geometry. © 2017, Springer-Verlag Berlin Heidelberg (outside the USA).

Lin K.-C.,Taitech Inc. | Kastengren A.,Argonne National Laboratory | Carter C.,Air Force Research Lab | Donbar J.,Air Force Research Lab
AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting | Year: 2017

Structures of the two-phase flows within the nozzle of an aerated-liquid injector were experimentally explored with synchrotron x-ray diagnostics, including pathlength-integrated and confocal x-ray fluorescence and x-ray high-speed imaging. Three beryllium nozzles with variations in passage contours and length were fabricated to mate with an aerated-liquid injector featuring the outside-in aerating scheme. Water and nitrogen were doped with x-ray fluorescent elements at low concentrations to facilitate the x-ray diagnostics. The present study shows that the two-phase flows inside the nozzle section exhibit an annular-like flow pattern, while the aerating gas is distributed in a Gaussian-like pattern. Axial distributions of the average liquid density, gas density, and liquid velocity were also explored by integrating the line-of-sight properties over several cross-sectional areas and axial locations within the nozzle section. For the present nozzle design with a convergent-divergent contour and a short passage length, the two-phase flow can be over-expanded, resulting in a low liquid density and a reversion in liquid momentum flux distribution within the divergent section of the nozzle. For the first time on these sprays, a confocal x-ray fluorescence measurement was carried out with a polycapillary x-ray optic to spatially resolve the cross-sectional mass distributions within the near field of various discharged plumes. Plume separation phenomena were readily observed in both liquid and gas plumes. High-speed imaging shows that large-scale structures are mainly present in the plenum section and can be aerodynamically stretched into fine structures near the nozzle exit. © 2017 by the American Institute of Aeronautics and Astronautics, Inc.

Sallam K.A.,Oklahoma State University | Lin K.-C.,Taitech Inc. | Hammack S.D.,Air Force Research Lab | Carter C.D.,Air Force Research Lab
AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting | Year: 2017

Inline digital holographic microscopy is used to study the spray structure in the nearinjector region of three different injectors in supersonic crossflow. Aerated liquid jets at different gas-to-liquid ratio (by mass) are compared to pure liquid jets for a crossflow Mach number of 2. Three-dimensional representations of the present test cases of aerated injection in supersonic crossflow are produced for the first time for the rapidly developing, near-injector region, owing to the capability of holographic diagnostics in probing nonspherical droplets (typical of this region). The results are also presented for the stable, farfield region of the injector (at 50 and 100 injector diameters downstream). The results include distributions of droplet equivalent-diameter and Sauter mean diameter, droplet velocities, spray penetration height, and plume width. © 2017 by Khaled A. Sallam.

Luo Z.,University of Connecticut | Lu T.,University of Connecticut | Liu J.,Taitech Inc.
Combustion and Flame | Year: 2011

A detailed mechanism for methane-ethylene mixtures enriched with excessive amount of NO was systematically reduced for efficient numerical simulations of flames in arc-heated co-flowing air. Methane and ethylene were selected as the surrogate fuel in the present study due to their drastically different features of ignition and extinction properties and flame propagation speeds, such that the mixtures of them may be utilized to mimic practical hydrocarbon fuels with various kinetic properties in experiments. The recently released USC Mech-II for C1-C4 was grafted with the NOx sub-mechanism in GRI-Mech 3.0 with updated reaction parameters for prompt NO formation. The resulting detailed mechanism with 129 species and 900 reactions was first validated against experiments involving NOx enrichment and reasonably good agreements were observed. The detailed mechanism was then employed as the starting mechanism for the reduction. A skeletal mechanism with 44 species and 269 reactions was derived using the methods of directed relation graph (DRG) and DRG-aided sensitivity analysis (DRGASA); a 39-species reduced mechanism with 35 semi-global reaction steps was further obtained using the linearized quasi steady state approximations (LQSSA). Five species related to prompt NO were retained in the reduced mechanism because of their significant impacts on the fuel oxidation. The reduced mechanism closely agrees with the detailed mechanism for ignition and extinction of homogenous mixtures, as well as selected 1-D flames over a wide range of parameters with NO concentrations between 0% and 3%. The observed worst-case relative error of the reduction is approximately 20%. The reduced mechanism was further validated with experiments involving excessive NOx enrichment. © 2010 The Combustion Institute.

Hassan E.,University of Michigan | Hassan E.,Air Force Research Lab | Boles J.,Taitech Inc. | Aono H.,Japan Aerospace Exploration Agency | And 3 more authors.
Progress in Aerospace Sciences | Year: 2013

The supersonic jet-in-crossflow problem which involves shocks, turbulent mixing, and large-scale vortical structures, requires special treatment for turbulence to obtain accurate solutions. Different turbulence modeling techniques are reviewed and compared in terms of their performance in predicting results consistent with the experimental data. Reynolds-averaged Navier-Stokes (RANS) models are limited in prediction of fuel structure due to their inability to accurately capture unsteadiness in the flow. Large eddy simulation (LES) is not yet practical due to prohibitively large grid requirement near the wall. Hybrid RANS/LES can offer reasonable compromise between accuracy and efficiency. The hybrid models are based on various approaches such as explicit blending of RANS and LES, detached eddy simulation (DES), and filter-based multi-scale models. In particular, they can be used to evaluate the turbulent Schmidt number modeling techniques used in jet-in-crossflow simulations. Specifically, an adaptive approach can be devised by utilizing the information obtained from the resolved field to help assign the value of turbulent Schmidt number in the sub-filter field. The adaptive approach combined with the multi-scale model improves the results especially when highly refined grids are needed to resolve small structures involved in the mixing process. © 2012 Elsevier Ltd.

Storch A.M.,Alliant Techsystems | Bynum M.,Alliant Techsystems | Liu J.,Taitech Inc | Gruber M.,Air Force Research Lab
17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference 2011 | Year: 2011

As part of the Hypersonic International Flight Research Experimentation (HIFiRE) Direct-Connect Rig (HDCR) test and analysis activity, three-dimensional computational fluid dynamics (CFD) simulations were performed using two Reynolds-Averaged Navier Stokes solvers. Measurements obtained from ground testing in the NASA Langley Arc-Heated Scramjet Test Facility (AHSTF) were used to specify inflow conditions for the simulations and combustor data from four representative tests were used as benchmarks. Test cases at simulated flight enthalpies of Mach 5.84, 6.5, 7.5, and 8.0 were analyzed. Modeling parameters (e.g., turbulent Schmidt number and compressibility treatment) were tuned such that the CFD results closely matched the experimental results. The tuned modeling parameters were used to establish a standard practice in HIFiRE combustor analysis. Combustor performance and operating mode were examined and were found to meet or exceed the objectives of the HIFiRE Flight 2 experiment. In addition, the calibrated CFD tools were then applied to make predictions of combustor operation and performance for the flight configuration and to aid in understanding the impacts of ground and flight uncertainties on combustor operation. © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

Lin K.-C.,Taitech Inc. | Rajnicek C.,Air Force Research Lab | McCall J.,Air Force Research Lab | Carter C.,Air Force Research Lab | Fezzaa K.,Argonne National Laboratory
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

Pure- and aerated-liquid jets were observed using the ultra-fast X-ray phase contrast imaging technique. Highly convoluted wrinkle structures were seen on the column surface of a turbulent pure-liquid jet, gas bubbles were discovered inside droplets and ligaments of aerated-liquid sprays, and apparently homogenous two-phase mixtures were observed inside the aerated-liquid injector. The major limitation of this X-ray technique lies in its line-of-sight nature, which can create overlapped objects/interfaces on the X-ray images. © 2011 Elsevier B.V. All rights reserved.

Liu J.,Taitech Inc | Gruber M.,Air Force Research Lab
17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference 2011 | Year: 2011

The HIFiRE Flight 2 experiment was designed to study mode transition and supersonic combustion performance using a surrogate hydrocarbon fuel over a Mach number range from 5.5 to 8. This paper describes a CFD effort to evaluate the operability and combustion performance of the HF2 flowpath configuration at different flight Mach numbers. The simulation results suggest that the present combustor operates in dual mode at Mach 6 with the primary injection equivalence ratio equal to or less than 0.7, and it transitions to scramjet mode between Mach 7 and 8. At Mach 8, the combustion performance exceeds the project goal with substantial margin. To increase confidence in the CFD predictions, two baseline cases were chosen for a sensitivity study on the total equivalence ratio, simulation geometry, near-wall turbulence treatment, and turbulence model. These parameters were found to have significant impact on combustion operability and heat transfer at some conditions. The results from the present sensitivity study may improve the understanding of some uncertainties in combustor operation during the ground and flight tests.

Edwards J.R.,North Carolina State University | Boles J.A.,Taitech Inc. | Baurle R.A.,NASA
Combustion and Flame | Year: 2012

This work presents results from large-eddy/Reynolds-averaged Navier-Stokes (LES/RANS) simulations of the well-known Burrows-Kurkov supersonic reacting wall-jet experiment. Generally good agreement with experimental mole fraction, stagnation temperature, and Pitot pressure profiles is obtained for non-reactive mixing of the hydrogen jet with a non-vitiated air stream. A lifted flame, stabilized between 15 and 20. cm downstream of the hydrogen jet, is formed for hydrogen injected into a vitiated air stream. Flame stabilization occurs closer to the hydrogen injection location when a three-dimensional combustor geometry (with boundary layer development resolved on all walls) is considered. Volumetric expansion of the reactive shear layer is accompanied by the formation of large eddies which interact strongly with the reaction zone. Time averaged predictions of the reaction zone structure show an under-prediction of the peak water concentration and stagnation temperature, relative to experimental data, but display generally good agreement with the extent of the reaction zone. Reactive scalar scatter plots indicate that the flame exhibits a transition from a partially-premixed flame structure, characterized by intermittent heat release, to a diffusion-flame structure that could probably be described by a strained laminar flamelet model. © 2011 The Combustion Institute.

Tam C.-J.,Taitech Inc. | Hsu K.-Y.,Innovative Scientific Solutions, Inc. | Hagenmaier M.,U.S. Air force | Raffoul C.,U.S. Air force
Journal of Propulsion and Power | Year: 2013

Direct-connect wind-tunnel facilities that produce uniform flow entering the test section are generally used for scramjet-component (isolator/combustor) studies. In freejet experiments and flight tests, however, air enters the engine through an inlet, and flow entering the isolator and combustor is typically distorted. The distortion effects can include nonuniform boundary-layer thicknesses on the walls and relatively strong oblique shock waves. This research focuses on the effects of inlet distortion on a round scramjet isolator. A numerical study was performed using various distortion devices, including ramps, injector ports, and injector slots, that were placed downstream of the directconnect facility nozzle to simulate a distorted flowfield from a prescribed inlet. The computational results provided a methodology for simulating flow distortion in direct-connect testing. Based on the numerical findings, experimental testing was conducted in the supersonic wind-tunnel facility to validate the numerical results and determine the impact of flow distortion. In addition, this paper focuses on design, fabrication, and execution of flow-distortion experiments. Air injection in the distortion section was used to create the flow distortion, and shock angle increases with the injection flow. Comparisons of wall pressure, exit flow profiles, and shock-holding capability are made from the experimental and numerical results. Good agreement between these data on wall pressures and flow profiles was found. Copyright © 2013 by the von Karman Institute for Fluid.

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