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Showing papers on "Dynamic pressure published in 1983"


Journal ArticleDOI
TL;DR: In this paper, an air-motion sensing technique for measurement of attack and sideslip angles and dynamic pressure was described, which consists of an array of five pressure holes in the standard radome of a twin-jet research aircraft.
Abstract: An air-motion sensing technique is described for measurement of attack and sideslip angles and dynamicpressure. The sensing probe consists of an array of five pressure holes in the standard radome of a twin-jetresearch aircraft. Comparisons are made with air motion measurements (angle of attack and dynamic pressure) obtained from a conventional differential pressure flow angle sensor at the tip of a nose boom 1.5fuselage diameters ahead of the aircraft body. The results indicate that the radome system works well downto scale sizes slightly larger than the fuselage diameter. (Finer scale measurements were limited by pressuretransducer response.) An insitu calibration technique is described for the determination of the empiricalradome angle-pressure difference sensitivity factor k, as a function of aircraft Mach number. The value ofk, so determined at low Mach numbers, is in approximate agreement with that calculated for potential flowfor a spherical radome. The in-situ technique applied to the con...

148 citations


Journal ArticleDOI
TL;DR: In this paper, a correlation for an aeroacoustic environment associated with attached compressible flow conditions was derived by using a transformation function to transform compressible data to the incompressible plane where direct use of more tractable prediction techniques are available for engineering design analyses.
Abstract: An examination has been made to derive a correlation for an aeroacoustic environment associated with attached compressible flow conditions. It was determined that fluctuating pressure characteristics described by incompressible theory as well as empirical correlations could be modified to a compressible state through a transformation function. In this manner, compressible data were transformed to the incompressible plane where direct use of more tractable prediction techniques are available for engineering design analyses. The investigation centered on algorithms associated with pressure magnitude and power spectral density. The method and subsequent prediction techniques are shown to be in excellent agreement with both incompressible and compressible flow data.

89 citations



Journal ArticleDOI
TL;DR: In this article, the vertical tail surfaces of a 13% F-15 model were measured in a low-speed wind tunnel with a pressure transducers mounted on rigid and flexible tails, and steady and unsteady pressures were obtained from the transducers at levels as low as 0.1% full scale.
Abstract: Buffeting pressures were measured on the vertical tail surfaces of a 13% F-15 model in a low-speed wind tunnel. Test variables included dynamic pressure, aircraft angle of attack, vertical tail incidence, and rudder deflection. Pressure transducers were flush mounted on rigid and flexible tails. Steady and unsteady pressures were obtained from the transducers at levels as low as 0.1% full scale. The steady pressures were integrated for aerodynamic coefficients and the unsteady pressures were reduced to spectral densities. The pressures are maximum at approximately 22 deg angle of attack and are significantly affected by tail flexibility.

60 citations


Journal ArticleDOI
TL;DR: In this article, a nonlinear theory is developed to determine accurately the hydrodynamic pressure on an accelerating vertical plate, where the plate is assumed to move horizontally towards the fluid with an acceleration which may be expressed in a power series in time.
Abstract: A nonlinear theory is developed to determine accurately the hydrodynamic pressure on an accelerating vertical plate. The plate is assumed to move horizontally towards the fluid with an acceleration which may be expressed in a power series in time. The fluid is initially at rest and the plate motion is impulsive. When the horizontal plate displacement is small in comparison with the undisturbed fluid depth, the method of small‐time expansions is adopted to obtain analytical solutions up to and including the third‐order velocity potential. The free surface profile of the fluid is also determined. An example for the constant acceleration case is presented to illustrate the method.

50 citations


Journal ArticleDOI
TL;DR: In this article, the static and dynamic characteristics of a negative pressure slider for magnetic recording disks were investigated using a modified Reynolds equation, which considers slip flow effects, calculated by divergence formulation and a finite difference method.
Abstract: This paper reports on investigations of static and dynamic characteristics of a negative pressure slider for magnetic recording disks. The negative pressure slider is composed of two narrow pressure pads, as on a cylindrical slider, separated by a rather large reverse step region. Through a modified Reynolds equation, which considers slip flow effects, the static and dynamic pressure distributions are calculated by divergence formulation and a finite difference method. Using the calculated results, the optimum reverse step depth is clarified in terms of both dynamic characteristics and wear caused by starting and stopping in contact with the disk. With a 4.6 mm length, 3.2 mm total pad width and 4 μm reverse step depth, the negative pressure slider has six times the air film stiffness of a conventional light load slider. Experimental data concerning spacing versus reverse step depth and take-off characteristics for the negative pressure slider in submicron spacing region are in good agreement with the calculated results.

26 citations


Patent
23 Jun 1983
TL;DR: In this article, an improved mass transfer or gas-liquid contact device having a specially contoured grid member (s) (26 to 36) interposed in the gas flow of the device was described.
Abstract: There is disclosed an improved mass transfer or gas-liquid contact device (10) having a specially contoured grid member (s) (26 to 36) interposed in the gas flow of the device (10) Ideally the grid member(s) have a cross-sectional profile which equals the sum of the theoretical velocity pressure profile of the gas flowing in an open vessel and the static and dynamic heads of the contacting liquid An additional depth is added to the grid approximately 5 to 40% more, to create an energy imbalance in favor of the introduced liquid, thereby allowing it to drain In existing vessels where it is desirable to replace prior art devices with an apparatus embodying the present invention, a plurality of grid modules may be employed, each module including a shaped grid or grid pair approximating the velocity profile of the gas stream in each

22 citations


Patent
13 Oct 1983
TL;DR: A flow-sensing pitot tube is disclosed for mounting in a conduit for indicating the rate of fluid flowing in the conduit as mentioned in this paper, which has forward openings facing up-stream for sensing dynamic pressure, and multiple static pressure sensing openings, including a pair disposed at an angle of 110 degrees rearwardly of the forward openings, for sensing static pressure.
Abstract: A flow-sensing pitot tube is disclosed for mounting in a conduit for indicating the rate of fluid flowing in the conduit. The tube has forward openings facing up-stream for sensing dynamic pressure, and multiple static pressure sensing openings, including a pair disposed at an angle of 110 degrees rearwardly of the forward openings, for sensing static pressure. Pressures sensed by the forward and rear openings are used to indicate volumetric flow by using a flow coefficient that is substantially independent of the Reynolds Number of the fluid.

20 citations


Journal ArticleDOI
TL;DR: A standard form for presenting the velocity-pressure gradient data is suggested and only one of the nine different types of presentations places the data in a form that is useable when solving for the air pressure distribution within a grain storage.
Abstract: THE presentation of pressure gradient vs. velocity data for air flow through grain is reviewed. Only one of the nine different types of presentations places the data in a form that is useable when solving for the air pressure distribution within a grain storage. A standard form for presenting the velocity-pressure gradient data is suggested.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of a series of vortices moving in the same idealized potential flow are also studied and the frequency of appearance of the vortice are determined from measurements.
Abstract: Noise generation at the edge of a wing flap is analyzed. The phenomenon as a single vortex moving around a corner in an incompressible, potential flow is modelled. Vortex image retarding effects are proposed as an explanation for small Strouhal numbers. The model surface pressures, sound pressures (using Curle's theory), and Mach number dependencies agree with wind tunnel experiments. A double pressure peak is found in the model (credited to image action) which is qualitatively similar to measured sound correlations. Incompressible flow aerosound calculations are discussed. The effects of a series of vortices moving in the same idealized potential flow are also studied. The vortices are assumed to be statistically independent so their intensities can be added. The frequency of appearance of the vortices are determined from measurements. Diffraction effects caused by the presence of the wing near the dipole sound radiators on the flap surfaces are included.

13 citations


Patent
28 Mar 1983
TL;DR: In this paper, the annular gap was used to enrich the fuel-air mixture at higher loads by adjusting the opening of the pressure chamber such that the dynamic pressure is smaller than the leak pressure to numbers corresponding turns of the higher rotor for the rotor.
Abstract: The annular gap (20) for sealing the rotor (14) of the device and extends around a pin (8) for feeding fuel is connected through a ball bearing (7) to a pressure chamber (40) for the intake air. When the rotor (14) is driven by the impeller (31, 38), the dynamic pressure acting in the annular gap is opposite to the leak pressure. By adapting the opening of the pressure chamber (40) adjusting the dynamic pressure to a value equal or slightly higher than that in the manner that the fuel leakage pressure can escape through the annular gap (20). Order to enrich the fuel-air mixture at higher loads is chosen an opening of the pressure chamber (40) such that the dynamic pressure is smaller than the leak pressure to numbers corresponding turns of the higher rotor for the rotor (14) delivers additional fuel. A vent conduit (42) connects the pressure chamber (40) with the annular chamber (33) which causes the fuel from its inlet (16) to a spray ring (35) disposed below the blades ( 38). This ventilation provides uninterrupted fuel flow in the annular chamber (33). This injection device provides a fuel-air mixture in which the harmful substances of the exhaust gases are below the limit values, without the appearance of peaks of the upper limit values.

Journal ArticleDOI
TL;DR: In this paper, the second peak pressure is studied experimentally with beaches having four different slopes and the authors found that the magnitude of second peak pressures is much lower than those of the first peak pressures.
Abstract: Secondary pressures resulting from the waves breaking on a vertical wall are studied experimentally with beaches having four different slopes. Pressure history of the wave impact consists of two distinct parts: The first peak and the second peak. The magnitudes of the second peak pressure are found to be much lower than those of the first peak pressures. The duration of the second peak pressure is considerably longer than the first peak pressure. The vertical distribution of simultaneous second peak pressure is almost linear vertically and this pressure is somewhat similar to a hydrostatic pressure. The major parameter affecting the second peak is the initial wave steepness. The effective pressure head is about the wave crest for low waves and moves below it for steep waves.

Patent
Richard O. Hessler1
14 Jan 1983
TL;DR: In this paper, a dynamic pressure comparator for calibrating high frequency pressure transducers used for the measurement of rocket motor combustion instability and other transient phenomena includes an acoustic cylindrical cavity through which a jet stream of nitrogen is passed and at each of the opposite ends of which a transducers carrier is provided.
Abstract: A dynamic pressure comparator for calibrating high frequency pressure transducers used for the measurement of rocket motor combustion instability and other transient phenomena includes an acoustic cylindrical cavity through which a jet stream of nitrogen is passed and at each of the opposite ends of which a transducer carrier is provided. Vortex systems and turbulence created as the jet enters and exits the cavity stimulate pressure transducers that are mounted in the carriers. The outputs of the transducers are monitored and compared as by the use of a spectrum analyzer. The comparator includes adjustments to vary the high frequency stimulus and the cavity pressure, and facilitates simulation of transducer installation in a given pressure measurement application, for example, on a rocket motor.

Patent
01 Apr 1983
TL;DR: In this paper, a pressure generator for testing and calibrating pressure transducers has a body with an internal chamber, which is filled with a liquid, statically pressurized, and a piston is mounted in the chamber on a suspension member.
Abstract: A pressure generator for testing and calibrating pressure transducers has a body with an internal chamber. The chamber is filled with a liquid, statically pressurized. A piston is mounted in the chamber on a suspension member. A coil, mounted to move with the piston, is arranged in a magnetic field. The coil is supplied with varying current to cause the piston to oscillate or dither in the chamber. Such oscillation creates a dynamic pressure which is superimposed on the static pressure. Openings are provided in the body to receive the sensing end of one or more pressure transducers.

01 Oct 1983
TL;DR: In this article, the process used in the application of aerodynamic uncertainties for the design and verification of the Space Shuttle Orbiter Entry Flight Control System is presented, where uncertainties were used to help set center of gravity, angle of attack and dynamic pressure lateral control divergence parameter as well as C sub n sub beta dynamic were instrumental in setting these placards.
Abstract: The process used in the application of aerodynamic uncertainties for the design and verification of the Space Shuttle Orbiter Entry Flight Control System is presented. The uncertainties were used to help set center of gravity, angle of attack and dynamic pressure lateral control divergence parameter as well as C sub n sub beta dynamic were instrumental in setting these placards.

Patent
05 Dec 1983
TL;DR: In this paper, a dynamic pressure removing device is formed by a duct having a static pressure measuring port 13 in the central part and a plurality of dynamic pressure attenuating bodies arranged in zigzag on both sides of the port.
Abstract: PURPOSE:To enable the measurement of a change in static pressure in a sure and stable manner, by arranging dynamic pressure attenuating bodies in zigzag in a duct so as to suppress the generation of dynamic pressure due to the wind or the like and to enable the measurement of the change in the static pressure alone CONSTITUTION:A dynamic pressure removing device 1 is formed by a duct 11 having a static pressure measuring port 13 in the central part and a plurality of dynamic pressure attenuating bodies 12 arranged in zigzag on both sides of the port The dynamic pressure removing device 1 thus formed is installed on the outside OB of a building and communicated with the inside IB of the building by a pressure conduction piping 2A It is further connected to the high pressure side H of a differential pressure detector 4 via a main detection valve 3, while a pressure conduction piping 2B is connected to the low pressure side L of the detector When a strong wind blows, an air current changes sharply However, the wind 6A and 6B entering the dynamic pressure removing device 1 is attenuated by the dynamic pressure attenuating bodies 12, and thus only a change in pressure at static pressure is applied on the differential pressure detector 4 By this constitution, the measurement of the static pressure can be performed in a stable and accurate manner

01 Oct 1983
TL;DR: In this paper, a wind tunnel test program of some complexity was used to define the aerodynamic forces exerted on the space shuttle solid rocket boosters and orbiter/external tank during staging.
Abstract: A wind tunnel test program of some complexity was used to define the aerodynamic forces exerted on the space shuttle solid rocket boosters and orbiter/external tank during staging. In these tests, problems associated with the use of up to three models in close proximity and with the need to simulate high pressure separation motor plumes were handled in a unique and effective manner. A new method was developed for efficiently organizing data which is a function of a large number of independent variables. Data derived from the test program drastically reduced previous estimates of aerodynamic uncertainties and allowed certification of the separation system at the design maximum staging dynamic pressure. Reduction of flight data has implicitly verified the staging aerodynamics data base and its associated uncertainties.

Journal ArticleDOI
TL;DR: A technique has been developed to evaluate the dynamic pressures on cylindrical structures due to irregular waves based on McCamy and Fuchs linear diffraction theory and principle of superposition as discussed by the authors.

01 Aug 1983
TL;DR: In this article, a portable dynamic pressure generator was developed to meet the requirements of determining the dynamic sensitivities of in situ pressure transducers at low frequencies, and tested up to 30 Hz and up to 13.8 kPa (2 psi).
Abstract: A portable dynamic pressure generator was developed to meet the requirements of determining the dynamic sensitivities of in situ pressure transducers at low frequencies. The device is designed to operate in a frequency range of 0 to 100 Hz, although it was only tested up to 30 Hz, and to generate dynamic pressures up to 13.8 kPa (2 psi). A description of the operating characteristics and instrumentation used for pressure, frequency, and displacement measurements is given. The pressure generator was used to statically and dynamically calibrate transducers. Test results demonstrated that a difference an exist between the static and dynamic sensitivity of a transducer, confirming the need for dynamic calibrations of in situ pressure transducers.

Patent
07 Nov 1983
TL;DR: In this paper, the authors propose to multiply energy by furnishing the pipeling with a bend and by allowing the dynamic pressure generated at this bend to return after passing through another line.
Abstract: PURPOSE:To multiply energy by furnishing the pipeling with a bend and by allowing the dynamic pressure generated at this bend to return after passing through another line. CONSTITUTION:If the liquid flows in a line 2 to get a bent 4 provided in the middle of this line and, there, presses the curvatures with a dynamic pressure of b kg/cm , so a pressure of (a+b)kg/cm is produced by the pressure energy of a kg/cm and the velocity energy to generate b kg/cm dynamic pressure. When this flows in the line 2 again to get the bend 4, only dynamic pressure thereamong passes through a line 5 to be transmitted to a point 6 to which the pressure shall be transmitted, so that the pressure energy will increase however much.

Patent
25 Jul 1983
TL;DR: In this paper, the authors proposed a method to test a dynamic characteristic by simulating a sudden rise of internal pressure in the event of a flashover fault of the inside of a test tank, by connecting the tank into which a liquid has been charged and a vessel into which high pressure gas had been charged by a connecting pipe through a pressure radiating film and an orifice.
Abstract: PURPOSE:To test a dynamic characteristic by simulating a sudden rise of internal pressure in the event of a flashover fault of the inside of a test tank, by connecting the tank into which a liquid has been charged and a vessel into which high pressure gas has been charged, by a connecting pipe through a pressure radiating film and an orifice. CONSTITUTION:A feed tank 1 into which insulating oil or water, etc. have been charged and a pressurized vessel 2 into which a high pressure gas body has been charged are connected by connecting pipes 5A, 5B through a pressure radiating film 3 and an orfice 4, and the end part of the connecting pipe 5B is tightly sealed by a partition film 8. Between the pressure radiating film 3 and the partition film 8, gas being about the atmospheric pressure is filled. When high pressure gas is led in through a gas charging valve 7, the pressure radiating film 3 is broken down by prescribed pressure, the partition film 8 is also broken down, and pressure in the test tank 1 rises suddenly. When the charging pressure of the gas body, the breakdown pressure of the pressure radiating film 3, and the diameter of the orifice are varied, and the position of the partition film 8 is adjusted, it becomes possible to execute a dynamic pressure test which has freely simulated a flashover fault in the tank.

Patent
03 Jun 1983
TL;DR: In this paper, an opening end is arranged toward the reverse direction to an intake flow in a reducing route 9 of blow-bye gas, so that the resultant pressure (dynamic pressure+static pressure) is controlled to an almost fixed level in no relation to engine speed.
Abstract: PURPOSE:To hold pressure or the like in an engine space part to a fixed level without causing the necessity for using a particular control valve, by arranging an opening end, which appears in an intake manifold of a reducing route of blow-bye gas, in the reverse direction to an intake air flow. CONSTITUTION:At high speed operation of an engine 1, negative pressure in an intake manifold 8, that is, static pressure increases to a minus direction, on the contrary, dynamic pressure generated by a flow of blow-bye gas increases to a plus direction. Accordingly, resultant pressure (dynamic pressure+static pressure) in an opening end 9a arranged toward the reverse direction to an intake flow in a reducing route 9 of blow-bye gas is controlled to an almost fixed level in no relation to an engine speed. In this way, pressure and flow of blow-bye gas in an engine space part 5 in a pipe P, crank case and cylinder head cover constituting the route 9 can be always held to a fixed level.


01 Jan 1983
TL;DR: In this article, a high aspect ratio supercritical wing with oscillating control surfaces is described and a semispan wing model was instrumented with 252 static pressure orifices and 164 in situ dynamic pressure gages for studying the effects of position and sinusoidal motion on steady and unsteady pressures.
Abstract: A high aspect ratio supercritical wing with oscillating control surfaces is described. The semispan wing model was instrumented with 252 static pressure orifices and 164 in situ dynamic pressure gages for studying the effects of control surface position and sinusoidal motion on steady and unsteady pressures. Results from the present test (the third in a series of tests on this model) were obtained in the Langley Transonic Dynamics Tunnel at Mach numbers of 0.60, 0.78, and 0.86 and are presented in tabular form.

Proceedings ArticleDOI
01 Jan 1983
TL;DR: Aerodynamic performance data from the first four Shuttle reentry flights are compared with pre-flight predictions covering hypersonic longitudinal mode down to Mach 2.5 as discussed by the authors, and the accuracy limits of the derived atmospheric densities are considered, together with potential data base updates in the light of limitations imposed on the corrections by available flight data.
Abstract: Aerodynamic performance data from the first four Shuttle reentry flights are compared with preflight predictions covering hypersonic longitudinal mode down to Mach 2. The extraction of the flight coefficients, as measured by the spacecraft angular rates and the linear accelerations, derived from the inertial measurement unit, the best estimate trajectory, and the remotely measured atmosphere are discussed. The ground predictions were developed from 30,000 hr of wind tunnel testing. Actual flight data are presented for 80-260 kft, from Mach 2-26, comprising the dynamic pressure, the vehicle air relative attitude angles, control surface deflections, reaction jet activity, and body axis rates and accelerations. The second and fourth flights gave results which deviated from predictions between 230-260 kft. The accuracy limits of the derived atmospheric densities are considered, together with potential data base updates in the light of limitations imposed on the corrections by available flight data.


Patent
02 May 1983
TL;DR: In this article, the authors proposed to block the invasion of dust to a closed chamber by introducing air dynamic pressure caused at the surrounding section of a magnetic disc to the center of the disc positively, and keeping the pressure of a bearing section to atmospheric pressure or over.
Abstract: PURPOSE:To block the invasion of dust to a closed chamber, by introducing air dynamic pressure caused at the surrounding section of a magnetic disc to the center of the disc positively, and keeping the pressure of a bearing section to atmospheric pressure or over. CONSTITUTION:A magnetic disc device main body 6 forms a closed chamber so as to shield a magnetic disc 1 from atmospheric pressures. The chamber is fitted with a duct 7, which has an air suction 7a around the magnetic disc 1 and an air delivery 7b around a bearing section. An air flow A is circulated through the duct 7. In rotating the magnetic disc 1, the part of air near the magnetic disc plane receives a centrifugal force to produce the air dynamic pressure around the disc. The part of the air flow enters the suction 7a, flows to the rotating center having a negative pressure, and brings the pressure to the atmospheric pressure.


Patent
15 Nov 1983
TL;DR: In this article, the authors proposed a method to automatically settle the dynamic pressure efficiently within a short time by generating a desired dynamic pressure in a shell correcting revolutions based on a difference from the desired value.
Abstract: PURPOSE:To automatically settle the dynamic pressure efficiently within a short time by generating a desired dynamic pressure in a shell correcting revolutions based on a difference from the desired value CONSTITUTION:The relationship q=KeN is determined between the revolutions (n) and the dynamic pressure (p) of a blower without a sample placed in a shell as shown by the straight line (m) and inputted into an electronic computer in the control system A dynamic pressure qset to be set is inputted to calculate revolutions n1 of the blower from the formula 1 When the difference between q1 and the set dynamic pressure qset is larger than the allowable errors of the dynamic pressure with the revolutions set at n1 (point a1), the revolutions n2 is calculated by the formula 2 and set to measure the dynamic pressure q (point a2) When the value q2 gives a large difference from the set dynamic pressure qset, the revolutions n3 of the blower are calculated by the formula 3 and set to measure the dynamic pressure q3 (point a3) The dynamic pressure q3 reaches the set dynamic pressure qset

01 Jun 1983
TL;DR: A study of electrical pressure transducers used to measure large caliber weapon chamber pressure was conducted at Aberdeen Proving Ground from January 1979 to March 1982 as discussed by the authors, at pressure levels from 34 to 785 MPa (5,000 to 110,000 PSI).
Abstract: : Measurements of pressure inside large caliber weapons are critical for establishing the balance between crew safety and combat effectiveness. A 2% error in chamber pressure measurement can result in a 3% change in weight, a 4% change in effective range, and a 6% change in fatigue life. A study of electrical pressure transducers used to measure large caliber weapon chamber pressure was conducted at Aberdeen Proving Ground from January 1979 to March 1982. Extensive testing, at pressure levels from 34 to 785 MPa (5,000 to 110,000 PSI) was done to evaluate 15 different types of pressure transducers. Tests to evaluate bias between readings from different types of transducers as well as the variability of readings produced by a single type of transducer were conducted. In the laboratory, both dynamic and static pressure readings were made. In the field, a 175mm gun was used to evaluate differences in transducer performance.