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The knowledge of transverse sonic injection flow field is very important for the design of scramjet combustor. Three dimensional Reynolds-Averaged Navier Stokes equations alongwith turbulence models are solved to find the effect of transverse sonic slot injection into a supersonic flow. Grid sensitivity of the results is studied for various structured grids. Simulations with different turbulence models (i.e., k-ε, k-ω, SST-kω, and RNG-kε) reveals that RNG-kε turbulence model better predicts the flow features. Computational fluid dynamics predicted wall pressure distribution for various injection pressures matches well with experimental data. The extent of upstream separated region increases with the increase of the injection pressure. The increase of slot width makes the interaction between transverse jet and free stream more intense and causes more spreading and penetration of injectant in the downstream region.

Introduction/purpose: In this paper, the aerodynamic characteristics of a special bullet were investigated at supersonic conditions. A model of a handgun saboted bullet was selected for the study. Methods: The method used in the research was computational fluid dynamic (CFD) simulation. The turbulence model k-e was used for numerical calculation. The air model was selected as an ideal gas. For air viscosity, the Sutherland model was applied. Results: The numerical simulation results show the behavior of the supersonic flow over the saboted bullet. By varying the petals opening angle and bullet velocity, their influences on the drags of the sabot and the penetrator were obtained to be used for later sabot separation study. Conclusion: The study shows that the CFD simulation approach can be implemented to analyze the aerodynamic drags on the sabot and the penetrator after the saboted bullet leaving the gun barrel. The simulation results obtained in this work are important in designing saboted light armorpiercing bullets fired from handguns.

Optical techniques for measuring the temperature in three-dimensional supersonic reactive flows have typically depended on lineshape measurements using single-beam laser absorption spectroscopy. However, absorption over extended path lengths in flows with symmetric, turbulent eddies can lead to systematically high extracted temperatures due to Doppler shifts resulting from flow along the absorption path. To eliminate these problems, Cross-Beam Saturation Absorption Spectroscopy (CBSAS) and Cross-Beam Inter-Modulated Fluorescence (CBIMF) have been developed which utilize two crossed and nearly copropogating laser beams.to record the spectral signal of an I2 ro-vibrational line in a small three-dimensional volume using a tunable CW dye laser. Temperature is extracted by fitting the recorded signal with a theoretical signal constructed from the Doppler-broadened hyperfine components of the ro-vibrational line. The CBIMF technique proved successful for extracting the temperature of an I2-seeded, Ar gas flow within a small, Mach 2, Laval nozzle where the overlap volume of the two 1 mm diameter laser beams was 2.4 mm3. At a test point downstream of the nozzle throat, the average temperature of 146 K ± 1.5 K extracted from measurements of the I2 P(46) 17-1 spectral line compared favorably with the 138 K temperature calculated from isentropic, one-dimensional flow theory.

Federal employment law designed to assure equal employment opportunity for faculty has only been applicable to higher education since 1972. Prior to 1972, the higher education world, moreover, was immune from the most comprehensive federal employment law, Title VII of the Civil Rights Act of 1964. However, Title VII was amended in 1972 to include education institutions. Ever since the protection of the civil rights law was extended to higher education, faculty employment discrimination litigation has increased. The reality of this phenomenal growth in litigation is clear, the potential for judicial intervention in academic decision making is undeniable, and reliance on the judicial process is increasingly becoming common. Thus, no institution of higher education may consider itself immune from the possibilities of litigation, nor immune from the decisions handed down by the courts. The main focus of this study was a legal one, which necessitated a heavy concentration upon the historical and current state of employment discrimination law, specifically, Title VII of the Civil Rights Act of 1964. The study was conducted by using a combination of legislative analysis and legal research methods. The legal research methods used in this study included the same problem-solving processes as other traditional research methods: (1) collecting data; (2) analysis; and (3) interpretation. The main purpose of this study was to examine, analyze, and summarize legislative history and case law relevant to Title VII, and sex discrimination in higher education. In summary, although Title VII prohibits discrimination on the basis of race, color, religion, sex and national origin, the issues surrounding women faculty and sex discrimination is probably the fastest growing area of litigation for administrators on the university campus. Therefore, this study was an attempt to examine the employment discrimination issues and developments pertaining to sex discrimination only. College and university administrators may find this study useful for: (1) examining Title VII, and its amendments; (2) examining sex discrimination case law; and (3) utilizing the research for developing procedures, policies and guidelines to minimize potential lawsuits. ; Ph. D.

Rocket nozzles are often cooled by passing liquid propellants through channels in the nozzle walls. Estimating heat transfer to the wall from the hot gases in the nozzle is essential in deciding on the coolant flow requirements. The present work examines the computational estimation of convection heat transfer to the nozzle walls for compressible turbulent flows. Computations were performed using the rhoPimpleFoam solver in OpenFOAM® with two different turbulence models. We simulate the supersonic flow over a flat plate and validate the heat flux calculation method and turbulence model characteristics. We compare two methods of calculating convection heat transfer in the context of the nozzle flow case presented by Back & Massier. We find that the realizablek-ε turbulence model works well in estimating the heat transfer coefficient.

Prepared at Langley Research Center. ; Bibliography: p. 13. ; Mode of access: Internet.

[EN] In the current paper, an investigation of the supersonic flow effect on shockwave generation and diesel spray penetration scaling has been performed. For this purpose, spray visualization tests have been carried out in a constant-pressure chamber at room temperature using shadowgraphy technique. Two working gases have been used: nitrogen, with similar thermodynamic characteristics to the engine environment, and sulfur hexafluoride, aimed at producing supersonic conditions at moderate injection pressure values. A total of 60 operating points, including different nozzle geometries, injection pressures and chamber densities have been studied. From the visualization study, two different kinds of shockwaves have been detected: normal or frontal, for moderate spray tip Mach (between 1 and 1.5); and oblique, when the Mach is higher than 1.5. The penetration results show that, for the same injection conditions in terms of injection pressure and chamber density, the spray propagation is equal for SF6 and N-2 when the spray is on subsonic conditions, while penetration is higher for SF6 when supersonic velocity is reached. This behavior has been related to the density gradient appearing across the shockwave. A new methodology to extrapolate supersonic penetration from the well-known subsonic penetration law has been proposed, showing good agreement with the experimental results. ; This work was partly sponsored by "Ministerio de Ciencia, Innovacion y Universidades", of the Spanish Government, in the frame of the Project "Estudio de la atomizacion primaria mediante simulaciones DNS y tecnicas opticas de muy alta resolucion", Reference RTI2018-099706-B-I00. ; Salvador, FJ.; De La Morena, J.; Taghavifar, H.; Nemati, A. (2020). Scaling spray penetration at supersonic conditions through shockwave analysis. Fuel. 260:1-7. https://doi.org/10.1016/j.fuel.2019.116308 ; S ; 1 ; 7 ; 260 ; Sazhin, S. S., Feng, G., & Heikal, M. R. (2001). A model for fuel spray penetration. Fuel, 80(15), 2171-2180. ...

Summary: The deceleration of air from supersonic velocities in channels has been studied. It has become apparent that a normal shock in the diverging part of the diffuser is probably necessary for stable flow, and ways of minimizing the intensity of this shock have been developed. The effect of various geometrical parameters, especially contraction ratio in the entrance region, on the performance of supersonic diffusers has been investigated. By the use of these results, diffusers were designed which, starting without initial boundary layer, recovered 90 percent of the kinetic energy in supersonic air streams up to a Mach number of 1.85. ; "CLASSIFIED DOCUMENT This document contains classified information affecting the National Defense of the United States within the meaning of the Espionage Act, USC 50:31 and 32. Its transmission or the revelation of its contents in any manner to an unauthorized person is prohibited by law. Information so classified may be imparted only to persons in the military and naval Services of the United States, appropriate civilian officers and employees of the Federal Government who have a legitimate interest therein, and to United States citizens of known loyalty and discretion who of necessity must be informed thereof." ; "Report date May 1945." ; "Advance Confidential Report L5D20." ; Summary: The deceleration of air from supersonic velocities in channels has been studied. It has become apparent that a normal shock in the diverging part of the diffuser is probably necessary for stable flow, and ways of minimizing the intensity of this shock have been developed. The effect of various geometrical parameters, especially contraction ratio in the entrance region, on the performance of supersonic diffusers has been investigated. By the use of these results, diffusers were designed which, starting without initial boundary layer, recovered 90 percent of the kinetic energy in supersonic air streams up to a Mach number of 1.85. ; Mode of access: Internet.

This is the final version. Available on open access from Elsevier via the DOI in this record ; The formation and evaporation of nanodroplets in steam ejectors is neglected in many numerical simulations. We analyse the influence of a primary nozzle on steam ejector performances considering phase change processes. The numerical model is validated in detail against experimental data of supersonic nozzles and steam ejectors available in the literature. The results show that the first nonequilibrium condensation is observed within the primary nozzle, while under-expanded supersonic flow causes a second nucleation-condensation process to achieve a large liquid fraction of 0.26 in the steam ejector. The compression process of the supersonic flow results in a steep decrease of the degree of subcooling leading to droplet evaporations. The condensation and evaporation processes repeat alternatively depending on the flow behaviour in the mixing section. The increasing area ratio leads to the transition of the flow structure from under-expanded flows to over-expanded flows in the mixing section. The droplet diameter is about 7 nm in the constant section and the entrainment ratio can reach approximately 0.75 for an area ratio of 8, which achieves a good performance of the steam ejector. ; European Union Horizon 2020 ; Independent Research Fund Denmark ; Innovation Fund of Denmark ; MAN Energy Solutions ; National Natural Science Foundation of China