Recursos de colección

Caltech Authors (142.336 recursos)

Repository of works by Caltech published authors.

Group = Hypersonic Research Project

Mostrando recursos 1 - 20 de 40

  1. The Effect of a Simple Throat Distortion on the Downstream Flow in a Hypersonic Wind Tunnel Nozzle

    Oliver, R. E.; Cummings, B. E.
    An experimental investigation was conducted in the GALCIT 2 1/2" Supersonic Wind Tunnel to determine the effect of a known distortion of the throat section of a hyper sonic nozzle on the flow in the region downstream from the throat. The flow in the nozzle with a rectangular throat section was compared with the flow in the same nozzle with the throat region distorted to produce a throat height which varied linearly across the throat section. The flow was investigated by means of Pitot pressure surveys in the horizontal plane of symmetry of the undistorted nozzle. The magnitude of the effect produced...

  2. Resistance Thermometer for Heat Transfer Measurements in a Shock Tube

    Rabinowicz, J.; Jessey, M. E.; Bartsch, C. A.
    This report describes a method for the application of the well-known principle of the resistance thermometer to the problem of measuring surface temperatures and heat transfer rates under highly transient conditions, such as are experienced in a shock tube. By using a thin platinum film sputtered on glass, a resistance thermometer gage is obtained which has a response lag of less than 1 µ sec, a linear output of 2-3 mv/°c, repeatability and durability. The gage preparation, including the sputtering technique, calibration method, and response characteristics are discussed, and some measurements of surface temperatures and heat transfer rates on models in...

  3. Propagation of an Initial Density Discontinuity

    Bienkowski, George
    The propagation of an initial one-dimensional density discontinuity is studied. The solution for times much shorter than the mean free time between collisions (i.e. collisionless), and the solution for times much longer than the mean free time (i.e. Euler) are functions of the same similarity variable x/t. They differ only in the details f the profiles. A method for evaluating the first effect of collisions is developed as an expansion in time with coefficients as functions of the similarity variable. The solutions are obtained in detail for both the Krook collision model and the exact collision integral for inverse fifth-power repulsion. The Krook model is...

  4. Nitrogen Injection into the Base Region of a Hypersonic Wake

    Herzog, Robert T.
    An experimental investigation was made of the changes occurring in the near wake of a cylinder at M = 6.0 when nitrogen was injected into the base region. The free stream Reynolds number based on cylinder diameter was 30,000 and the rate of injection was varied from zero to 3 percent of the frontal area free stream mass flow. Pitot pressure profiles across the wake, Schlieren photographs and measurement of the boundary layer separation point on the cylinder were used to define the changes in wake geometry. Static pressure and temperature surveys were made along the wake centerline starting at the base...

  5. Inviscid Hypersonic Flow Over Blunt-Nosed Slender Bodies

    Lees, Lester
    At hypersonic speeds the drag/area of a blunt nose is much larger than the drag/area of a slender afterbody, and the energy contained in the flow field in a plane at right angles to the flight direction is nearly constant over a downstream distance many times greater than the characteristic nose dimension. The transverse flow field exhibits certain similarity properties directly analogous to the flow similarity behind an intense blast wave found by G. I. Taylor and S. C. Lin. Conditions for constant energy show that the shape of the bow shock wave R(x) not too close to the nose is...

  6. An Experimental Investigation of the Flow over Blunt-Nosed Cones at a Mach Number of 5.8

    Machell, Reginald M.; O'Bryant, William T.
    Shock shapes were observed and static pressures were measured on spherically-blunted cones at a nominal Mach number of 5.8 over a range of Reynolds numbers per inch from 97,000 to 238,000, for angles of yaw from 0° to 8°. Six combinations of the bluntness ratios 0.4, 0.8, and l.064 with the cone half angles 10°, 20°, and 40° were used in determining the significant parameters governing pressure distribution. The pressure distribution on the spherical nose for both yawed and unyawed bodies is predicted quite accurately by the modified Newtonian theory given by C_p = C_(P_(max)) cos ^2 η, where η is the...

  7. Finite Disturbance Effect on the Stability of a Laminar Incompressible Wake Behind a Flat Plate

    Ko, Denny R. S.; Kubota, Toshi; Lees, Lester
    An integral method is used to investigate the interaction between the stability of a single frequency finite amplitude disturbance with the non-parallel mean flow in a laminar, incompressible wake behind a flat plate. The mean flow is assumed to be characterized by a few shape parameters. The integrals involving the fluctuating components are determined as functions of those shape parameters by solving the inviscid Rayleigh equation of the linear stability theory using the local mean flow. The variations of the amplitude of the fluctuation and the mean flow in the streamwise direction are then determined from solving the set of ordinary differential...

  8. A Preliminary Experimental Investigation of the Flow over Simple Bodies of Revolution at M=18.4 in Helium

    Munson, Albert G.
    An experimental investigation was conducted in the GALCIT hypersonic blow-down tunnel to determine surface pressure distributions and shock wave shapes for a series of "sharp"-nosed and slightly-blunted bodies of revolution at a nominal Mach number of 18.4 and a free stream Reynolds number of 6.20 x 10^5 per inch. The four bodies investigated were as follows: (1) 15° half-angle "sharp" cone; (2) 15° half-angle spherically-blunt cone (bluntness ratio= .24); (3) 20° half-angle "sharp" cone; (4) 2/3-power body. The pressure distributions on the "sharp" cones agreed well with the Taylor-Maccoll theory. As expected, the pressure near the nose of the blunt cone was much higher...

  9. Hypersonic Flow over a Yawed Circular Cone

    Tracy, Richard R.
    A 10° semi-apex, circular cone is tested in air at Mach 8 and at 0 yaw angles to 24°; surface pressure, heat transfer, and pitot-pressure throughout the flow field are presented. The nominal surface temperature is 40" of the free stream stagnation temperature, and the Reynolds nunber, based on cone generator length, is varied from 0.5 x 10^5 to 4.2 x 10^5 . Heat transfer is measured at higher surface temperature ratios (up to 56%) and Reynolds nunbers (up to 7.3 x 10^5) by reducing the free stream stagnation temperature. All raw data consist of continuous circumferential distributions of each quantity and are...

  10. Flow Generated by a Suddenly Heated Flat Plate

    Wu, Ying-chu Lin
    By employing the two-sided Maxwellian in Maxwell's moment method a kinetic theory description is obtained of the flow generated by a step-function increase in the temperature of an infinite flat plate. Four moments are employed in order to satisfy the three conservation equations, plus one additional equation involving the heat flux in the direction normal to the plate. For a small temperature rise the equations are linearized, and closed-form solutions are obtained for small and large time in terms of the average collision time. Initially the disturbances propagate along two distinct characteristics, but the discontinuities across these waves damp out as time increases. At...

  11. Hypersonic Wakes

    McCarthy, John F., Jr.
    An experimental investigation was made of the flow field behind a two-dimensional circular cylinder at a nominal Mach number of 5.7. The free-stream Reynolds number based on the cylinder diameter was varied over a range from 4300 to 66, 500 by changing both the diameter of the cylinder and the stagnation pressure of the wind tunnel. Pitot-pressure, static-pressure, and total-temperature measurements were made at various distances behind the cylindrical rod in order to determine the state properties in the wake. Base-pressure measurements were also taken at various Reynolds numbers. From these measurements, the transition from laminar to turbulent flow in the wake was determined...

  12. An Experimental Investigation of the Effect of a Transverse Hypersonic Flow Velocity upon a Low-Density D. C. Electrical Discharge in Air

    Marlotte, Gary L.
    The low-density D. C. electrical discharge in a uniform gas stationary with respect to the electrodes has been studied extensively. However. when the gas moves at a hypersonic speed transverse to the electrodes, several completely new effects are introduced. Experiments were carried out with air in the GALCIT 5-inch by 5-inch hypersonic wind tunnel with a nominal Mach number of 5.8. D. C. breakdown voltages and steady-state sub-normal glow voltages were measured across a channel formed by two sharp-edged insulating flat plates in which flat-plate "Rogowski" electrodes were embedded. Segmented electrodes were then used in the normal glow regime to measure current...

  13. Kinetic Theory Description of Conductive Heat Transfer from a Fine Wire

    Lees, Lester; Liu, Chung-Yen
    The Maxwell moment method utilizing the two-sided Maxwellian distribution function is applied to the problem of conductive heat transfer between two concentric cylinders at rest. Analytical solutions are obtained for small temperature differences between the cylinders. The predicted heat transfer agrees very well with experiments performed by Bomelburg, Schäfer-Rating and Eucken. Comparison with results given by Grad's thirteen moment equations, and with those given by Fourier's "law" plus the Maxwell-Smoluchowski temperature-jump boundary condition shows that the two-sided character in the distribution function is a crucial factor in problems involving surface curvature.

  14. Experimental Investigation of an Arc Heater

    Renard, Marc L.
    An electric arc heater, intended to provide a steady flow of high stagnation temperature gas (up to 10,000°K) into a convergent-divergent nozzle, was designed at the GALCIT Hypersonic Laboratory. Section 2 first gives a few preliminary calculations which have been made for the arc heater-nozzle combination, using argon, at stagnation pressures of 1 and 2 atm., and assuming equilibrium flow. In particular, the Mach number in the test section of a fixed nozzle will depend on the thermodynamic properties at the reservoir. In the heater, the direct-current arc is axially constricted by a channel parallel to the gas flow. A description of...

  15. Hot-wire Measurements in Low Reynolds Number Hypersonic Flows

    Dewey, C. Forbes, Jr.
    Measurements were made of the heat loss and recovery temperature of a fine hot-wire at a nominal Mach number of 5.8. Data were obtained over an eight-fold range of Reynolds numbers in the transitional regime between continuum and free-molecule flow. At high Reynolds numbers, the heat transfer data agree well with the results of Laufer and McClellan, which were obtained at lower Mach numbers. At lower Reynolds numbers, the results indicate a monotonic transition between continuum and free molecule heat transfer laws. The slope of the heat transfer correlation also appears to vary monotonically, with Nu=√Re at high Reynolds numbers and Nu...

  16. Development and Calibration of a Cold Wire Probe for Use in Shock Tubes

    Christiansen, Walter H.
    Th e use of a fine unheated wire for making s hock tube flow measurements is investigated. The operation of the instrument depends on the transient nature of the shock tube flow. The wire is referred to here as a cold wire; it operates in a non-steady manner which is completely different from the usual hot wire operation. This report describe s the construction and calibration of the cold wire. The experimental law for the rate of gain of heat to the wire 1n air is determine d over a range of Mach numbers from 0.4 to 1.9 and a range of Reynolds...

  17. Energy Transfer Processes in a Partially Ionized Gas

    Cann, Gordon L.
    The following paper is divided into three more or less separate sections. The first section (Chapters II- VI) deals with an analysis of the transport properties of a partially ionized gas subject to the constraint that the average random energy of all constituent particles is exactly equal (equipartition of energy). This constraint is necessary so that the formal Chapman-Enskog solution of Boltzman's equation can be used to evaluate the various transport coefficients. Subject to this constraint, a set of tractable equations describing the mass and energy diffusion in a partially ionized gas is obtained that includes all terms correct to the order of...

  18. Experimental Study of Helium and Argon Diffusion in the Wake of a circular Cylinder at M=5.8

    Kingsland, Louis, Jr.
    Experimental measurements of the diffusion of helium and argon in the wake of a porous cylinder were made in the GALCIT hypersonic wind tunnel at Mach number 5. 8. The cylinder was mounted perpendicular to the flow and small quantities of tracer gas were pumped through the model walls into the flow. The thermal conductivity method of gas analysis was used to determine the concentration of sample gases extracted from points in the wake. The transverse and axial distribution of concentration appeared to follow theoretical estimates of "similarity behavior". Injection of tracer gas was found to have a measurable effect on stagnation...

  19. Small Perturbations in the Unsteady Flow of a Rarefied Gas Based on Grad's Thirteen Moment Approximation

    Ai, Daniel Kwoh-i
    In this paper, the unsteady one-dimensional flow of a compressible, viscous and heat conducting fluid is treated, based on linearized Grad's thirteen moment equations. The fluid, initially at rest, is set into motion by some small external disturbances. Our interest is to examine the nature of all the responses. The fluid field extends to infinity in both directions; thus no length is involved, and also there is no solid wall boundary existing in the problem. The nature of the external disturbances is restricted to having a unit impulse in the momentum equation and a unit heat addition in the energy equation. The disturbances...

  20. Kinetic Theory Description of Plane, Compressible Couette Flow

    Lees, Lester; Liu, Chung-Yen
    By utilizing the two-stream Maxwellian in Maxwell's integral equations of transfer we are able to find a closed-form solution of the problem of compressible plane Couette flow over the whole range of gas density from free molecule flow to atmospheric. The ratio of shear stress to the product of ordinary viscosity and velocity gradient, which is unity for a Newtonian fluid, here depends also on the gas density, the plate temperatures and the plate spacing. For example, this ratio decreases rapidly with increasing plate Mach number when the plate temperatures are fixed. On the other hand, at a fixed Mach number based on...

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