Browsing by Author "Beckmann, Herbert K."
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Item A calculation of pressure recovery behind a normal shock in hypersonic flow(1960) Murray, Robert H; Beckmann, Herbert K.An analytical model is devised for investigating the flow immediately behind the normal shock which stands in the throat of the conical shock diffuser of a hypersonic wind tunnel. A method is developed for calculating the flow properties, specifically the static and total pressures, for the case of large heat losses to the wall. An example is worked out to illustrate the method and some typical results.Item A method to measure the mass specific impulse of partially ionized helium(1960) Patterson, Maurice M; Beckmann, Herbert K.An apparatus to measure the mass specific impulse, Isp, of partially ionized helium flowing in a converging-diverging nozzle, was designed and fabricated. The mass specific impulse increased as the stagnation enthalpy, 110, increased. The effect on the mass specific impulse and the exit enthalpy, h2, of varying nozzle length (and area ratio) was observed. The maximum mass specific impulse measured in this investigation was approximately four times the mass specific impulse of a high performance chemical rocket fuel.Item An experimental analysis of the transport of drilled particles in an annulus(1970) Zeidler, Hermann Udo; Beckmann, Herbert K.Laboratory tests were carried out to study the removal of drilled particles in a well borehole simulated annulus. The main objectives of these tests were to determine the effect of varying: (1) the particle size and particle size distribution; (2) the annular flow rate; (3) the fluid type viscosity and density; (4) the rate of rotation of the inner pipe. Dropping tests with individual particles of various sizes were also performed to study the behavior of, and to determine the settling velocity of these particles in a quiescent Newtonian fluid medium of varying viscosity. From these experiments a general settling velocity equation applicable to all particle sizes and an expression for the cumulative mass fraction of particles removed from the annulus are formulated. It was concluded that: (1) Under a given constant state, the total mass fraction of particles removed may be less than one. (2) At low annular flow rates, the first arrival time, (tmin)ap, for any one particle size may be greater than the minimum time based on the relative average fluid and single particle settling velocities. (3) The initial number of particles of any one particular particle size affects fcmax and (tmin)ap. (4) Rotating the inner pipe does increase the rate at which particles are removed and the total number of particles removed. (5) Introducing a drilling mud into the annulus may or may not increase the rate at which particles are removed, compared to the same annular flow rates using water. The exact behavior of the particles under these conditions was not determined, and the reduction of Reynolds number from turbulent to laminar flow by use of the drilling muds does not permit a true comparison between water and drilling muds. (6) In the laminar flow of drilling muds, it appears that one must consider both the relative flatness of velocity profiles and the particle Reynolds number in evaluating the carrying capacity capabilities of these fluids. A flatter velocity profile (low power law exponent) alone does not necessarily insure better carrying capacity.Item An experimental investigation of the variation with water depth of lift or drag coefficients of a body on or near the bottom of a flowing stream(1969) Smith, Conrad Michael; Beckmann, Herbert K.An experimental investigation was carried out for the purpose of determining the influence of the depth of water upon the coefficients of lift and drag of a submerged body on or near the bottom of a flowing stream. This investigation made use of the facilities of the Rice University wave tank. Two types of models were employed in this study, an upright flat plate attached to the bottom and a cylinder with a clearance of ,12 diameters above the bottom. The results of the tests indicate that the drag coefficient increases as the size of the body increases in relation to the depth of water, while the lift coefficient does not exhibit such an increase, A method is developed which predicts the shallow-water drag coefficient with an accuracy of +/- 1% if the value of the deep-water coefficient and the upstream conditions are known. The same method can be used to obtain a deep-water coefficient from tests conducted in shallow water.Item Applications of a mathematical model of the human body for determining thermal comfort(1984) Hill, Gregory Wade; Chapman, Alan J.; Wierum, Frederic A.; Beckmann, Herbert K.A conceptual description of a current mathematical model of the human body, analyzed in terms of heat transfer, is presented. This model is designed to predict thermal comfort responses of a person exposed to a particular indoor environment. Methods of heat exchange between the body core, the skin, and the surroundings are described. Formulations are also included for two parameters describing the environment-the mean radiant temperature and the convective heat transfer coefficient. Heat transfer equations and computer programs for this model are used to generate data for the study. Three applications for this model are discussed in terms of their effectiveness in achieving thermal comfort: the effect of radiant cooling panels, the effect of ceiling fans, and the effect a change in the person's metabolic rate. In each example, the temperature of the surroundings is displaced from a reference temperature where thermal comfort exists. Efforts to restore the sensation of comfort are examined and the results are illustrated in graphical and tabular form. Conclusions are drawn from the procedure and recommendations for future research are suggested.Item Boundary layer growth in a converging nozzle(1961) Glasscock, Melbern Gilbert; Beckmann, Herbert K.A solution to the boundary layer equations for en incompressible fluid flow through a converging nozzle is presented. Calculations are based on a nozzle whose walls have a constant radius of curvature and a 2:1 entrance area to throat area ratio. An equation for the free stream velocity es a function of the arc length of the nozzle is derived, and the Blasius series for flow around a circular cylinder is applied to as much of the nozzle as the approximation will permit. Graphs of the velocity profiles, variation of shear stress and displacement thickness era presented.Item Characteristics of supersonic thrust nozzles for low density plasmas(1962) Bertin, John J., 1938-; Beckmann, Herbert K.The thrust characteristics of a conical nozzle were experimentally determined using helium, partially ionized by a high energy electric arc, as the working fluid. The thrust produced in the supersonic section of the nozzle is presented in dimensionless form as the total thrust less the thrust produced in the convergent section. Data for divergence half angles of 20°, 25°, and 30° are presented as a function of the Reynolds number and the ratio of the exit area to the throat area for area ratios varying from unity to 250. The experimental thrust data were compared with values predicted by one dimensional nozzle theory corrected for boundary layer effects.Item Determination of the flow field in a confined vortex chamber(1963) Schulz-Jander, Burkhard; Beckmann, Herbert K.The flow field in a cylindrical vortex chamber was investigated experimentally. The tangential velocity distribution was found to resemble a solid body rotation in the outer region, and a vortex flow in the center. A theory derived for the pressure and velocity distributions agreed very well with experiments. Close to the flat walls a secondary flow towards the center of the vortex was detected, which contributed to most of the mass flow through the chamber.Item Electrical properties of argon gas emerging from a plasma jet(1959) Martinez, Eugene Paul; Beckmann, Herbert K.Argon gas, which had been partly ionized by an electric arc with an enthalpy input in the order of 104 BTU/lbm was expanded through a supersonic wind tunnel nozzle. It was found to contain residual positive ions in excess of electrons. These residual ions amounted to 10 to the -4 times the total number of flowing atoms; a slight increase occurred with decreasing enthalpy input. This quantity also represented the only residual ions of the gas jet leaving the expansion nozzle at ambient temperature and a pressure of 0.25 mm Hg. Normalization of these ions was achieved by means of diffusion to the surface of the pipe recapturing the free jet.Item Fluctuations of an electric arc in a plasma generator(1962) Kahn, Michael Edwin; Beckmann, Herbert K.Argon gas was expanded in a supersonic nozzle after being partially ionized by a high-energy electric arc. The frequency of arc voltage oscillation was found to be inversely proportional to the power input to the arc. This was probably due to the motion of the arc with the vortex flow in the arc chamber. When a parallel resonant circuit was inserted in series with the arc, significant oscillation occurred over a range of frequencies from 15 KC to 30 KC. The energy exchanged between the coil and capacitor of the parallel resonant circuit was calculated. Due to the small magnitudes of the oscillation energy and the relatively low frequencies, it was concluded that the magnetic induction of the coils used could not produce any detectable excitation of the gas.Item Hydraulic evaluation of filter screens for power plant water intake(1979) Kamata, Masahiro; Walker, William F.; Beckmann, Herbert K.; Picologlou, Basil F.An investigation has been performed of hydrodynamic losses through filter screens used in power plant water intakes. For the experimental phase of the investigation, screens with aspect ratio up to 3.8 were tested. The Reynolds number range for the test was from 15-1 and the ratio of traveling screen velocity to water approach velocity varied from -1.. It was found that the characteristics of flow through slot mesh screens are similar to those for flow through square mesh screens. The losses through round wire screens can be estimated from the approach water velocity, wire diameter, and a function of the ratio of opening area to frontal area of the screen. If a finer screen mesh is desired for filtering purposes, slot mesh screens sustain smaller hydrodynamic losses than square mesh screens because the ratio of openings is larger. It was also found that the screen motion in the water could be easily simulated. It was determined that the losses for a traveling screen are the same as those for a stationary screen of the same design so long as the normal component of the approach velocity remains unchanged.Item Measurement of pressure recovery and the degree of ionization downstream of a strong normal shock(1961) Willis, Noel Charles; Beckmann, Herbert K.Helium was expended through a supersonic nozzle in a wind tunnel after being partially ionized by an electric arc. Calculations based on the stagnation proportion of the gas end the area ratio of the nozzle indicated that the static pressure in the wind tunnel was too high to allow isentropic expansion of the gas. A previous investigation noted an extreme reduction of thrust output at this area ratio, as compared to the thrust obtained at smaller area ratios, indicating the possibility of a chock in the nozzle. Probes wore developed to measure the degree of ionization and pressure downstream of a normal shock. From these two properties, the free stream properties of the gas were calculated. The Mach number was far below that predicted for isentropic expansion, indicating that a shock did occur in the nozzle.Item Melting within a spherical enclosure(1981) Moore, Frank Evins; Bayazitoglu, Yildiz; Beckmann, Herbert K.; Chapman, Alan J.The problem considered is that of the melting of a phase change material, initially at its saturation temperature, which is enclosed within a spherical shell whose surface temperature is suddenly raised to some fixed value. The density of the solid is assumed to exceed the density of the liquid, the implication being that the solid will continually drop toward the bottom of the shell as melting progresses. This bulk motion of the solid generates a flow field within the liquid, which gives rise to shear and pressure forces that must balance the weight of the solid. The energy equation written for the liquid region is solved in conjunction with an interface heat balance equation, while the velocity field is calculated approximately by assuming a parabolic profile for the polar component of velocity and neglecting the radial component. After making a suitable variable' transformation, the energy equation and the interface equation are expressed in finite difference form. The energy equation is solved by the alternating direction method, while the interface equation is solved using a modified Newton-Raphson procedure. Experimental evidence confirms the dropping solid hypothesis, and has permitted a limited quantitative verification of the mathematical model.Item Performance characteristics of Lorentz accelerators(1964) Lazar, Janos Jozsef; Beckmann, Herbert K.An experimental study was made of the performance of Lorentz accelerators. Such accelerators involve the application of electric and magnetic fields to accelerate flows of partially ionized gases. Propulsion efficiencies of the accelerator of up to 28% were obtained indicating the possibility of achieving even higher efficiencies with accelerators of more advanced design. Thrust efficiencies in the vicinity of 90% were achieved; and overall efficiencies of 50% were obtained for the combined performance of the plasma generator and the Lorentz accelerator. Currents up to 1000 amperes and magnetic fields up to 0.205 webers/m2 were used. The optimum magnetic field was found to be approximately 0.180 weber/m2.Item Performance of an arc chamber(1962) Hendrickson, Bruce Irwin; Beckmann, Herbert K.The performance of a plasma generator which used arc heating was studied with helium and hydrogen as the working gases. An optimum electrode gap and chamber diameter were determined for a stagnation pressure between 1 and 1.5 atmospheres by computing the efficiency of the unit for various values of these parameters. Two methods of increasing the specific impulse of the test gas at sonic velocity were studied using optimum chamber conditions. First, the energy input to the gas was increased to approximately 1.5 X 105 cal/gram for hydrogen; and a maximum specific impulse of 2300 grams force over grams mass/sec was obtained. Further increases in the specific impulse resulted from removal of boundary layer gas at the throat. A theory, assuming separate regimes of flow at the throat, was developed to explain this increase.Item Performance of plasma jets at sonic velocity(1961) Knight, James Roger; Beckmann, Herbert K.An experimental program was carried out to investigate the flow properties of partly ionized monatomic gases in the converging section of a nozzle. Choked flow was maintained at the throat, and the stagnation pressure, mass flow rate, and thrust at the throat were measured. The thrust at the throat is essentially a function of the stagnation pressure. Deviations from the predicted values were interpreted as representing losses due to heat transfer, friction, and turbulence. The thrust data was compared with the values predicted by a one-dimensional isentropic flow theory for partly ionized gases expanding in thermal equilibrium. The theory, presented in terms of dimensionless flow parameters, was valid for any monatomic gas. Data obtained, when plotted in dimensionless form, showed the same deviation from the idealized relationships for both helium and argon.Item Reflection of ionizing oblique shockwaves(1961) Harrison, Lyndon H; Beckmann, Herbert K.The difficulties encountered in obtaining a solution for the regular reflection of an oblique ionizing shock wave at a wall are discussed. In general it was not possible to obtain the entire solution for the shock pattern from one dimensional flow considerations. However, in the flow region relatively far removed from the wall, a free stream region, a solution may be obtained which will give both the equilibrium and nonequilibrium fluid properties behind the incident and reflected shocks as well as the reflected wave angle. It is also shown that for the case where reaction thicknesses may be considered negligible this will be the complete solution. In order to obtain a solution for the flow across a shock wave, the conservation equations of mass, energy, and momentum are solved simultaneously with the equation of state and an expression for the ionization reaction rate. Due to the nature of the equations only a numerical solution was possible, therefore, the method is demonstrated for a particular set of initial conditions.Item Relaxation phenomena in ionized gases(1960) Cloud, Wayne B; Beckmann, Herbert K.An analytical solution of one dimensional equilibrium and frozen flow is presented. The "Idealized Recombination Relation" for volume electron-ion recombination is applied to frozen flow to obtain a stepwise solution. Calculations are made on partially ionized helium to illustrate the deviation between a frozen type flow and an equilibrium type flow.Item The dispersion and generation of sea states(1967) Turner, Edward Hugh; Beckmann, Herbert K.This paper deals with a method of generating a desired sea state in a wave tank. The time duration in which all wave groups are present at the test section and before reflected waves reach the test section is maximized for a given length of wave tank. The duration is found to be dependent on the number of frequency bands chosen to represent the spectrum. The more frequency bands chosen and consequently, the better the spectrum is approximated, the shorter the duration. Each frequency band is approximated by two sine waves of equal amplitude. The frequency bands must be chosen so that they can be adequately represented by two waves.Item Thermal comfort study of one window-walled room(1979) Smith, Jan Preston; Chapman, Alan J.; Beckmann, Herbert K.; Wierum, Frederic A.Human comfort as a function of location in a room with one window wall at a temperature different from the other walls is studied. Computer models of the radiant field in a room and of the thermal response of the human body are used to obtain the experimental data. The factors affecting human comfort in a typical office room with one wall exposed to common northern United States winter temperatures are discussed in detail. The computer programs utilized in this research are described and their appropriateness as models is justified with current thermal environmental information. The parameters of the research are outlined, and a description of the goals and assumptions is given. The conclusions reached from the research are documented in graphs and text.