Showing papers on "Shock tube published in 1969"

Rarefied Gas Dynamics

Abstract: Collisional Processes.- Analytical Formulae for Cross Sections and Rate Constants of Elementary Processes in Gases.- Relaxation of Velocity Distribution of Electrons Cooled (Heated) By Rotational Excitation (De-Excitation) Of N2.- Effects of the Initial Molecular States in a High-Energy Scattering of Molecular Beams.- Differential Cross Sections for Ion-Pair Formation with Selection of the Exit Channel.- Low-temperature Viscosity Cross Sections Measured in a Supersonic Argon Beam II.- Excited Oxygen Iodine Kinetic Studies.- Determination of Antisymmetric Mode Energy of CO2 Injected into a Supersonic Nitrogen Flow.- Molecular Beams.- Where are we going with molecular beams?.- Cesium Vapor Jettarget Produced With a Supersonic Nozzle.- Basic Features of the Generation and Diagnostics of Atomic Hydrogen Beams in the Ground and Metastable 22S1/2-States to Determine the Fundamental Physical Constants.- Optical Pumping Of Metastable Neon Atoms in A Weak Magnetic Field.- CO2-Laser Excitation of a Molecular Beam Monitored By Spontaneous Raman Effect.- Time-of-Flight and Electron Beam Fluorescence Diagnostics: Optimal Experimental Designs.- Molecular Beam Time-of-Flight Measurements in A Nearly Freejet Expansion of High Temperature Gas Produced By a Shock Tube.- Electron Beam Diagnostics.- Electron-Beam Diagnostics of High Temperature Rarefied Gas Flows.- Excitation Models Used in the Electron Beam Fluorescence Technique.- Electron - Beam Diagnostics in Nitrogen Multiquantum Rotational Transitions.- Free Jets, Nonequilibrium Expansions.- Free Jet as an Object of Nonequilibrium Processes Investigation.- State Dependent Angular Distributions of Na2 Molecules in a Na/Na2 Free Jet Expansion.- Molecular Beam Time-of-Flight Measurements and Moment Method Calculations of Translational Relaxation in Highly Heated Free Jets of Monatomic Gas Mixtures.- Rovibrational State Population Distributions of CO (v ? 4, J ? 10) In Highly Heated Supersonic Free Jets of CO-N2 Mixtures.- Free Jet Expansion with A Strong Condensation Effect.- Measured Densities in UF6 Free Jets.- Rotational Relaxation of NO in Seeded, Pulsed Nozzle Beams.- The Free-Jet Expansion from a Capillary Source.- Rotational Relaxation in High Temperature Jets of Nitrogen.- Translational Nonequilibrium in a Free Jet Expansion of a Binary Gas Mixture.- Laser Induced Fluorescence Study of Free Jet Expansions.- Jet-Surface Interactions.- Experimental Study of Plume Impingement and Heating Effect on Ariane's Payload.- The Interaction of a Jet Exhausting from a Body with a Supersonic Free Flow of a Rarefied Gas.- Modelling Control Thruster Plume Flow and Impingement.- Impingement of a Supersonic, Underexpanded Rarefied Jet upon a Flat Plate.- Some Peculiarities of Power and Heat Interaction of a Low Density Highly Underexpanded Jet with a Flat Plate.- Condensation in Flows.- Nonequilibrium Condensation in Free Jets.- Condensation and Vapour-Liquid Interaction in a Reflected Shock Region.- Homogeneous and Heterogeneous Condensation of Nitrogen in Transonic Flow.- Investigation of Nonequilibrium Homogeneous Gas Condensation.- The Peculiarities of Condensation Process in Conical Nozzle and in Free Jet Behind it.- Investigation of Nonequilibrium Argon Condensation In Supersonic Jet By Mass-Spectrometry, Electron Diffraction and VUV Emission Spectroscopy.- Clusters and Nucleation Kinetics.- The Microscopic Theory of Clustering and Nucleation.- Kinetics of Cluster Formation and Growth in the Process of Isothermal Condensation.- Relaxation Processes in a Molecular Dynamic Model of Cluster from the Lennard-Jones Particles.- Quantum-Chemical Study Of Processes With Cluster Isomerism.- The Homogeneous Nucleation at the Continuously Changing Temperature and Vapour Concentration.- Molecular Clusters as Heterogeneous Condensation Nuclei.- Experiments with Clusters.- The Photochemistry of Small van der Waals Molecules as Studied by Laser Spectroscopy in Supersonic Free Jets.- Diagnostics of Clusters in Molecular Beams.- Experimental Studies of Water-Aerosol Explosive Vaporization.- Laser Probing of Cluster Formation and Dissociation in Molecular Beams.- Free Molecule Drag on Helium Clusters.- Vibrational Relaxation Kinetics in a Two-Phase Gas-Cluster System.- Gas-Particle Flows.- Long-Range Attraction in the Collisions of Free-Molecular and Transition Regime Aerosol Particles.- Nonequilibrium Statistical Theory of Dispersed Systems.- The Mechanism of Strong Electric Field Effect on the Dispersed Media in the Rarefied Gas.- Generation of High-Speed Aerosol Beams By Laval Nozzles.- Kinetic Model of a Gas Suspension.- Gas Mixtures.- Kinetic Phenomena in the Rarefied Gas Mixtures Flowing Through Channels.- On the Discrete Boltzmann Equation for Binary Gas Mixtures.- Peculiarities and Applicability Conditions of Macroscopic Description of Disparate Molecular Masses Mixture Motion.- Numerical Solution of the Boltzmann Kinetic Equation for the Binary Gas Mixture.- Species Isotope Separation.- Gas or Isotope Separation by Injection into Light Gas Flow.- Molecular Diffusion Through a Fine-Pored Filter Versus Resonante IR-Radiation Intensity.- On Limiting Situations of Gas Dynamic Separation.- A Study of Reverse Leaks.- Investigation of Nonequilibrium Effects in Separation Nozzles by Monte-Carlo Simulation.- Separation of Binary Gas Mixtures at their Effusion through a Capillary and a Nuclear Filler into Vacuum.- Ionized Gases.- Effects of Nonideality in Quantum Kinetic Theory.- Molecular Mass and Heat Transfer of Chemical Equilibrium Multicomponent Partially Ionized Gases in Electromagnetic Field.- Spectroscopic Study of a Plasma Flow along the Stagnation Streamline of a Blunt Body.- On Model Kinetic Operators and Corresponding Langevin Sources for a Non-Equilibrium Plasma.- Related Fields.- Rarefied Gas Dynamics as Related to Controlled Thermonuclear Fusion.- Vacuum Ejectors with Appreciably Uneven Flows in Channels at Low Reynolds Numbers.- Simulation of the Process of the Cosmic Body Formation.

Influence of Reflected Shock and Boundary‐Layer Interaction on Shock‐Tube Flows

Abstract: During the last decade the study of the interaction between normal shocks and boundary layers in the shock tube has been carried out by many research workers. This interest has been fostered by the requirement to understand the effects that this phenomenon may have on the flow properties in the region between the reflected shock and the end of the tube. This so‐called reflected shock region is important in chemical kinetics studies and as a reservoir of gas for hypersonic shock tunnels. In this paper a review is given of the various analyses of the problem together with the results of experimental studies. Reflected and transmitted shock bifurcation, the rate of growth of the bifurcated foot, and the effects of transition to turbulence are discussed. The influence of bifurcation on the flow in the shock tube is assessed, especially as a mechanism for transporting cold driver gas to the end plate, causing early cooling of the gas on the reflected shock region.

Location of action of burning-rate catalysts in composite propellantcombustion.

Abstract: H + 62 + M -> HO2 + M Reaction in Lean Hydrogen-Oxygen Mixtures," Journal of Chemical Physics, Vol 43, No 9, Nov 1965, pp 3237-3247 7 Getzinger, R W, "A Shock Wave Study of Recombination in Near Stoichiometric Hydrogen-Oxygen Mixtures," Eleventh Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa, 1967, pp 117-124 s Stull, D R, JANAF Thermochemical Tables, Dow Chemical Co, Midland, Mich; may be purchased as Rept PB-168370 ($1000) and addenda PB-168370-1 and PB-168370-2 ($300 each), National Bureau of Standards, CFSTI, US Dept of Commerce, Springfield, Va 9 Bird, P F, Duff, R E, and Schott, G L, "HUG, a Fortran-Fap Code for Computing Normal Shock and Detonation Parameters in Gases," Rept LA-2980, Feb 1964, Los Alamos Scientific Lab, The Univ of California, Los Alamos, N Mex 10 White, D R and Millikan, R C, "Oxygen Vibrational Relaxation in O2-H2 Mixtures," Journal of Chemical Physics, Vol 39, No 8, Oct 1963, pp 2107-2108 11 White, D R and Millikan, R C, "Vibrational Relaxation of Oxygen," Journal of Chemical Physics, Vol 39, No 7 Oct 1963, pp1803-1806 12 White, D R and Millikan, R C, "Oxygen Vibrational Relaxation in O2-He and O2-Ar Mixtures," Journal of Chemical Physics, Vol 39, No 7, Oct 1963, pp 1807-1808 13 Gilbert, R B and Strehlow, R A, "Theory of Detonation Initiation Behind Reflected Shock Waves," AIAA Journal, Vol 4, No 10, Oct 1966, pp 1777-1783 14 Getzinger, R W and Blair, L S, "A Shock Tube Study of the Effects of Nitrogen and Water Vapor on Recombination in the Hydrogen-Oxygen System," 6th International Shock Tube Symposium, Freiberg, Germany, April 12-14, 1967; also The Physics of Fluids, to be published 15 Shchelkin, K I and Troshin, Ya K, Gas Dynamics of Combustion, Mono Book Corp, Baltimore, Md, 1965, pp 1-53 16 Voitsekhovskii, B V, Mitrofanov, V V, and Topchian, M E, Struktura Fronta Detonatsii v Gaza, Akademiya Nauk SSSR Novosibirsk, 1963, pp 81-96; transl as The Structure of a Detonation Front in Gases, Rept FTD-MT-64-527 (AD 633821), Feb 1966, Foreign Technology Div, Wright-Patterson Air Force Base, Ohio, pp 81-97 17 Strehlow, R A and Engels, C D, "Transverse Waves in Detonations II Structure and Spacing in H2—O-2, C2H2—O2, C2H4—O2 and CEU—O2 Systems," AIAA Journal, to be published

Shock waves from spark discharges

Abstract: Measurements of the expansion rates of the cylindrical shock waves produced in the early stages of spark-channel formation are given. Comparison with predicted rates, based on an improved analytical treatment, are satisfactory.

Erratum: Vibrational Relaxation in CO2 and CO2–Ar Mixtures Studied Using a Shock Tube and a Laser–Schlieren Technique

Abstract: Vibrational relaxation has been studied in CO2 and CO2–Ar mixtures over the temperature range 360°–3000°K using a laser–schlieren method. The purpose of this investigation was to compare the results obtained by this technique with those deduced using a Mach–Zehnder interferometer and to provide further evidence as to whether relaxation times depend upon how far the system is from equilibrium as well as on the translational temperature. Relaxation times measured by these two methods agree well. The laser–schlieren method is the more satisfactory for measuring the rate of relaxation and the Mach–Zehnder for finding the total density change during the process. These new results support the view that relaxation times do not depend upon how far the system is from equilibrium. The measurements using CO2 and CO2–Ar mixtures show that CO2 is about five times as effective as Ar in causing relaxation at 360°K and two times as effective at 2000°K.

Investigations of the Aerodynamic Characteristics of the Shock Tubes : (Part 1, The Effects of Tube Diameter on the Tube Performance)

Abstract: The effects of tube diameter on the propagation behavior of a shock front were investigated by using two shock tubes with different sizes and by comparing with the other data. The process of the formation of a shock front when the diaphragm was ruptured was observed by schlieren method. From this experiment, it was found that the observed shock Mach numbers were larger than the values obtained by the simple theory. Such result depends on the opening time of the diaphragm and the diameter of the tube. Therefore, the various factors influencing the opening time of the diaphragm and the shock formation distance were discussed and the functional relations between these factors were clarified using the dimensional analysis. The expression for the shock formation distance derived by the dimensional analysis was in satisfactory agreement with the experimental results.

Emission and absorption measurements on a strongly self-absorbed argon atom line

Abstract: Spectroscopic measurements of the 7635·10 ArI line were made on an argon plasma generated in a free burning arc. The emission profile, corrected for self-absorption, was measured over a temperature range of 10 000°K to 22 000°K at 1 atm pressure. Self-absorption had a strong effect on the measured transition probability but little effect on the temperature profile that was obtained using the Fowler-Milne technique. Kirchhoff's law was used to demonstrate local thermodynamic equilibrium. An iterative technique that corrected line profiles using Kirchhoff's law yielded results that agreed with the measured line profiles. The transition probability measured in this study is 2 1 2 times greater than that reported in a shock tube experiment. Using the measured absorption coefficients, corrections were applied to the shock tube measurement giving a transtition probability that agrees with the one reported in this study.

Two-phase detonation of a liquid layer.

Abstract: Two phase detonations of fuel in liquid layer on shock tube wall with gaseous oxidizer, presenting one dimensional approximation for film detonation propagation

Experimental study of high-enthalpy shock- tunnel flow. I - Shock-tube flow and nozzle starting time.

Abstract: The results of an experimental study of shock-tube and nozzle (reflected-shock-tunnel) flows for incident-shock Mach numbers ranging from 85 to 165 are reported The test gas used in these experiments was either air or nitrogen and the driver gas was either hydrogen or helium Incident-shock test times were measured using several diagnostic techniques for laminar boundary layers and for conditions at which boundary-layer transition occurred within the test-gas slug The laminar boundary-layer data were found to be in excellent agreement with the theory The data obtained for the transitional boundary-layer case are compared with the theory for fully turbulent boundary-layer flow because of the absence of an appropriate theory The reflected-shock pressure dip frequently observed to follow the pressure plateau that occurs immediately after shock reflection was also studied The results suggest that the dip is caused by an expansion wave generated upon initial interaction of the reflected shock with the driver-driven gas interface The pressure dip was present to some degree for all combinations of driver and test gases studied However, the dip was most pronounced for the case of hydrogen driving air possibly due to interface combustion The starting time was studied in a 13° half-angle conical nozzle for two shock-tube Mach numbers, 165 and 115, using air as the test gas and hydrogen as the driver gas Several diagnostic methods were used in the nozzle including microwave interferometers, photomultipiier tubes, and piezoelectric pressure transducers The starting-time measurements made with these various techniques are shown to be generally in agreement A result of these studies is that the measured time after shock reflection required to establish uniform flow at a given axial location in the nozzle can be reasonably predicted by integration of the quantity dx/(u — a)

Interpretation of pressure measurements behind the reflected shock in a rectangular shock tube.

Abstract: value of L/H = 10 to 12 as the value at which the type of cavity flow changes. Figure 5 indicates that much higher heating rates exist on the cavity floor for closed cavity flow, due to the reattachment region and increased heating in the downstream compression corner. (Note the similarity of heating distribution for L/H = 15 and 30 downstream corners with Fig. 1 for forward-facing steps.) The open cavity flow condition is seen to have relatively low heating rates (h/hQ < 0.5) over two-thirds of the floor, increasing to the order of attached flow heating near the downstream end. Similar heating distributions were obtained by Charwat et al. and Emery et al. for open cavity flow at Me = 2,9.

Investigations of the Aerodynamic Characteristics of the Shock Tubes : (Part 2,On the Formation of Shock Waves)

Abstract: To explain the mechanism of the shock formation in a simple shock tube, the multi-stage model was presented, which improved White's theory, and some numerical calculations were carried out. Simple and White's theories correspond respectively to the case of zero or one stage of the present multi-stage model. The shock Mach number calculated by the multi-stage model is always larger than that obtained by the White's model. The difference between them becomes large as the diaphragm pressure ratio increases. Further in order to express the variation of the shock Mach number along the tube a function II (x) was proposed. By using this function, the phenomenon that shocks stronger than that predicted by the simple theory would possibly happen was discussed.

Isotopic exchange between oxygen and carbon monoxide in shock waves.

Abstract: The isotopic exchange reaction between 18O2 and CO has been studied in a shock tube coupled to a time‐of‐flight mass spectrometer, over the temperature range 1700°–2600°K, using very dilute CO+O2 mixtures in neon. The rate is found to increase with time. Auxiliary studies of the 16O2–18O2 exchange reaction and of the 18O2–C16O exchange reaction induced by nitrous oxide pyrolysis have demonstrated that this exchange occurs via an atomic mechanism. The rates of O‐atom attack on O2 and CO are found to be almost equal over the temperature range studied. Using the known rate of N2O decomposition, at 1820°K the calculated rate constants for these two reactions are 11. × 10−12 and 6.6 × 10−12 cm3/molecule·sec, respectively, in excellent agreement with the extrapolations of the low‐temperature values in the literature. The reaction producing O atoms in the absence of N2O is equal order in both O2 and CO but the over‐all order is uncertain. The observed activation energy of the initiation process is less than that...

A critique of high-performance shock tube driving techniques.

Abstract: : The various high-performance shock tube driving techniques considered have been grouped as high pressure/high speed of sound conventional drivers, electric and magnetic field interaction drivers, detonation drivers, and those that derive their flow characteristics from the coupling of energy addition and wave processes in an unconventional manner. 'High performance' can be taken to refer to any property of a shock tube flow that is important to a particular study: for example, shock velocity, driven gas temperature, pressure, and density levels, driven gas kinetic to static energy ratio, and uniformity and duration of the driven gas flow. Data from recent references are compared to determine the relative effectiveness of different driving techniques and the predictability of flow properties. Several fluid dynamic problem areas are outlined; requirements for their study in shock driven facilities are discussed and compared with capabilities resulting from the use of various driving techniques. (Author)

Experimental and analytical study of H sub 2-air reaction kinetics using a standing-wave normal shock.

Abstract: : An experimental method was devised whereby the macroscopic chemical reaction history can be traced from wall pressure measurements in a high speed reacting gas in a tube. The experiments were conducted with H2 and vitiated air, and the data were compared with calculated pressure profiles using recent reaction kinetic information obtained from shock tubes. Good agreement between experiment and calculation was found when the flow was steady and no oscillations were present, indicating that the kinetics which govern the chemical reactions in shock tube experiments can be reproduced with the standing-wave experiment. Wall effects are evaluated. In addition, a semi- empirical analysis was made of the ignition delay and recombination, with the assumption that the two-body reactions are essentially in equilibrium during the slower recombination period. The mathematics of this approach is simple and is potentially useful with machine computations involving chemistry and mixing, or chemistry and aerodynamics. Finally, a short experiment with methane combustion in the tube produced similar phenomena, indicating that the method may be useful for determining rates of heat release for gases where little is known of the kinetics.

Shock‐Tube Study of OH (2Σ — 2Π) Luminescence

Abstract: OH (2Σ — 2Π) emission was studied in 1500‐2800°K incident shock waves through low‐pressure H2‐O2‐Ar mixtures with 100‐fold variation in H2/O2 ratio. The transition from chemiluminescent to thermal excitation was found to occur near 2000‐2200°K for these conditions. Intensities measured during the exponential growth period and in the partial equilibrium state following combustion were correlated with possible elementary reactions producing OH(2Σ).

Dependence of Shock‐Tube Boundary Layers on Shock Strength

Abstract: Using familiar considerations of vorticity transport, the essential behavior of shock‐tube boundary layers is explicitly exhibited; the nearly constant functions that cannot be calculated analytically are evaluated numerically and compared with Mirels' correlations.

Shock-Tube Study of the Dissociation Rate of CN

Abstract: The rate of the reaction CN+Ar→C+N+Ar is estimated to be 2.5 ± 1 × 10−10exp[(− 71 000 ± 6000) / T] cm3sec−1 over the temperature range 7000°–15 000°K from a study of the decay of CN radiation excited by the passage of a shock wave through a mixture of BrCN and Ar. The formation of C2 and N2 introduces a major uncertainty in the interpretation of the results.

The interaction region in the boundary layer of a shock tube

Abstract: Velocity and temperature boundary layers developed on a plane wall by ideal shock-tube flow are considered for weak shock and expansion waves. Analytically, the boundary layer consists of three regions, bounded by (1) expansion-wave head, (2) diaphragm location, (3) contact discontinuity, (4) shock. The flow fields (1, 2) and (3, 4) are, essentially, known. In the interaction region (2, 3), these flow fields merge, the governing equations are ‘singular parabolic’ and admit boundary conditions usually associated with elliptic equations. It is convenient to replace the weak expansion wave in the main flow by a line discontinuity. A consistent linearization scheme can now be devised to obtain the solution in the three regions. In (2, 3), the resulting linear singular parabolic equations for the first-order solutions are solved successfully by an iterative finite difference method, normally applied to elliptic equations.

Shock tube techniques and instrumentation

Abstract: : A survey of shock tube techniques and instrumentation is presented. Ideal shock tube theory is outlined as are various phenomena which influence actual performance. Shock tubes designed for specific purposes are described. Shock tube instrumentation is discussed in terms of the variable to be measured.

High‐Temperature‐Air Microwave Breakdown

Abstract: The test section of an electric‐arc shock tube was used to explore the dependence of microwave breakdown behavior on elevated gas temperature. Special diagnostic techniques included microwave interferometry and a flat‐plate ion density probe. Results for air, nitrogen, and argon are in agreement with the proposed theory, and the importance of the nitrogen molecule in explaining the air data is established in the context of the theoretical model.

Electron density measurements ahead of shock waves in air

Abstract: Precursor electron densities measured in nitrogen and air ahead of shock waves, noting shock tube wall reflectivity