Showing papers on "Dynamic pressure published in 1968"

Mean drop size resulting from the injection of a liquid jet into a high-speed gas stream.

Abstract: The mean drop size generated by a liquid jet penetrating a gaseous environment is estimated. There are at least four regimes of interest which may be separated according to the relative dynamic pressure. The two regimes having the higher dynamic pressure are treated here. Primary drop generation is treated for the case when the unstable waves grow and are dominated by capillary action (region 3) as well as acceleration forces (region 4). The theoretical results are found to be reasonably consistent with experimental data found in the literature.

Experiments on the snapping of a shallow dome under a step pressure load.

Abstract: : The dynamic step pressure loads required to produce snapping are determined experimentally for two shallow spherical shell models. The resulting critical step pressures are compared with static buckling pressures that were obtained from the results of a nondestructive buckling test. The comparison reveals that the critical step pressures were between 55 and 58% of the static buckling pressure for one model and between 63 and 64% of the static buckling pressure for the other model. The measured supercritical response of the shells was similar to the predictions of theory. (Author)

A Numerical Experiment in Dry and Moist Convection Including the Rain Stage

Abstract: Dry and moist convective slab-symmetric cells, initiated by means of a buoyant bubble, have been studied by solving numerically the appropriate physical equations. In the case of moist convection, by including the bulk effects of the microphysics of cloud and precipitation, a precipitating roll cloud was simulated. The pressure distribution accompanying the convection was obtained by solving a partial differential equation (the balance equation). The dynamic pressure is much different from the hydrostatic pressure. Forces governing the vertical motion have been studied in some detail. The pressure force is shown to initiate and maintain inflow and outflow in the convective cell and to create forced descent outside the rising bubble as required by mass continuity. It also opposes the upward motion of the bubble and gives rise to a drag similar to the form drag of a body moving through a viscous fluid. A “hot tower” develops near the top of the cloud while negative buoyancy develops in its lower ha...

High-speed monorail rocket sleds for aerodynamic testing at high Reynolds numbers.

Abstract: The use of a monorail rocket-sled system is detailed and recommended as a method of obtaining aerodynamic data in a regime of high Mach and Reynolds numbers. Sled designs and the data collection system are discussed in detail. The system has been used successfully to acquire pressure data on cone-cylinders. These data are compared with data from free-flight rockets, wind-tunnel tests, and computer calculations. The sled-testing technique appears to be the most promising method of simulating flight conditions at low altitudes at Mach numbers up to M = 8. A principal advantage is the high degree of accuracy possible in determining actual test conditions, which include Mach number, static pressure, and static temperature. Exploratory tests indicate that sleds may be used to collect other types of experimental data such as heat-transfer and boundary-layer transition. To date, excellent data have been obtained at 7430 fps (M = 6.53), which to our knowledge is the highest velocity ever attained by a rocket sled. At this speed, and the Holloman Air Force Base track altitude, the Reynolds number was 42 X 106/ft, and the dynamic pressure was 55,000 psf. Nomenclature CD, CL = drag and lift coefficients, respectively, based on sled cross-sectional area M = Mach number Pm = measured model surface pressure POO = freestream ambient pressure Re = freestream Reynolds number To, Tw, Tm = total, wall, and freestream temperatures, respectively U = freestream velocity, fps

Apparatus for measuring the density of liquids

Abstract: A closed space filled with a reference liquid is arranged within a container for the process liquid of which the density is to be measured, the confining walls of the closed space consisting at least partly of a flexible material adapted to transmit pressure between the two liquids; and means are provided for sensing at the same level the pressure of the process liquid and the pressure of the reference liquid, and for comparing the sensed pressures. The process liquid may be passed continuously through the container by way of inlet and outlet openings so arranged that any dynamic pressure variation has counteracting effects on the two sensed pressures, due to the flexible wall.

Nonlinear flutter of loaded plates.

Abstract: Nonlinear flutter of flat plates under transverse /static pressure/ and in-plane loads, emphasizing low supersonic flow regime

A compressor stator vane control system

Abstract: 1,124,693. Compressors; gas turbine plant. UNITED AIRCRAFT CORP. Sept. 15, 1966, No.41211/66. Headings F1C and F1G. [Also in Division G3] A compressor stator vane control system comprises an actuator for varying the angular position of the vanes and means responsive to a function of the Mach number of the fluid passing through the compressor for controlling the actuator. In a gas turbine engine, Fig. 1 (not shown), the control system comprises probes (18, 22) subjected respectively to the static and total air pressures at the inlet to the compressor guide vanes (12) and connected to lines 20, 24. Line 20 is connected to sensor 66 to position a valve 60 according to the static pressure and both lines 20, 24 are connected to sensor 78 to position a valve 62 according to the dynamic pressure. Valves 60, 62 control the position of the spool 56 of a scheduling valve 28 in the hydraulic circuit of the vane actuator 14, port 90 in the valve being contoured to represent the schedule of the vane angle for a given value of the ratio of dynamic to static pressure, i.e. of Mach number. The fluid from port 90 acts to position the spool 106 of a servo valve 30 controlling the flow to either side of the piston 32 of the vane actuator 14, a feedback 100 from the piston rod 34 adjusting a valve 98 according to the actual vane position. In a modification, the pressure measuring probes (18, 22) are positioned downstream of the stator guide vanes. The control system may be used with axial or radial flow compressors.