Showing papers on "Dynamic pressure published in 1982"

Fluid pressure sensing apparatus

Abstract: A fluid pressure sensor apparatus includes one or a plurality of fluid pressure sensor elements. Each fluid pressure sensor element comprises a flat hollow structure which extends transverse to the direction of flow of a fluid. An upstream chamber is open through dynamic pressure measuring holes which extend in the direction of the flow, and a downstream chamber is open through static pressure measuring holes which extend transverse to the flow direction. The upstream chamber acts to average the dynamic pressure and the downstream chamber measures static pressure. An auxiliary ridge-like member is located downstream of the static pressure measuring holes.

Internal Pressure and Building Safety

Abstract: The wind-induced pressure inside buildings has a profound effect on building safety. Yet, little attention has been given to it in the past. The effect is either ignored or improperly considered in contemporary building codes or standards. This paper seeks to clarify the matter and improve the way internal pressure is considered in the design of buildings. Both static and dynamic effects of internal pressure are considered herein. The dynamic effects include the overshooting of internal pressure following the breakage of a windward window during high wind, and the Helmholtz resonance created by any disturbance. Combined effects of internal and external pressure variations are also reviewed.

The cryogenic wind tunnel for high Reynolds number testing

Abstract: An improved way to increase the Reynolds numbers capability of wind tunnels has been developed at the Langley Research Center. Cooling the test gas to cryogenic temperatures by spraying liquid nitrogen into the tunnel circuit increases Reynolds number with no increase in dynamic pressure and a reduction in drive power. In addition, the ability to vary the temperature of the test gas independently of pressure and Mach number allows for the first time the independent determination of Reynolds number, Mach number, and aeroelastic effects. A new fan-driven transonic cryogenic tunnel being built at the Langley Research Center will provide an order of magnitude increase in Reynolds number capability over existing transonic tunnels in the United States when it is completed later this year.

Pressure measurements on twin vertical tails in buffeting flow

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.

Gas-dynamic pressure wave machine with exhaust gas bypass

Abstract: A gas-dynamic pressure wave machine with an exhaust gas bypass (11) which includes a flap (12) provided in the bypass (11) which opens with higher engine speeds in order to limit the peak pressure in the internal combustion engine (9). A flap control is provided via a pressure box (14) with a process pressure, for example, exhaust gas pressure, as the controlling dimension. The process pressure is coupled with a constant pressure such as a vacuum or excess pressure for altitude compensation and temperature compensation in such a manner that the process pressure is to be raised by the same amount with a decreasing atmospheric pressure. For this purpose, the pressure box (14) is divided into first and second separate chambers (16, 17) by means of a diaphragm (15) and the process pressure acts on the first chamber while the second chamber is maintained under a constant pressure. The diaphragm (15) acts on the flap (12) through a plurality of rods (19-23).

Compound guide system of machine tool

Abstract: PURPOSE:To prevent uneven pressure on guide faces as well as partial contact between a moving body and guide faces by providing a slide-guiding face for a dynamic pressure as one of a pair of opposite slide guiding faces of a machine tool and for a static pressure as the other. CONSTITUTION:A grinder axis housing 101 is guided by columns 102, 103 and makes a vertical motion by a feed screw 104. A static pressure guide board 105 is connected with the grinder axis housing 101 by a bolt. As regards the C direction, a pair of static pressure guide faces 207, 208 is provided in opposition to a pair of dynamic pressure sliding guide faces 205, 206. Thus, a pair of dynamic pressure sliding guide faces 205, 206 is the only standard of movement, while the static pressure guide faces 207, 208 perform equalized pressure distribution in guide faces 205, 206.

Apparatus for measuring flowing gas or air stream parameters

Abstract: not available for EP0057069Abstract of corresponding document: US4388691A device which can determine either the velocity pressure or the velocity of a flowing gas or air stream and averages same over a predetermined period of time is disclosed. The device utilizes a three-hole yaw probe or similar sensing means which is immersed in the stream to provide measurements of both static pressure differential and velocity pressure. The device includes a null threshold detector (14) which permits the processing of velocity pressure measurements only when the static pressure differential is within a pre-set range thus insuring the proper alignment of the probe or other sensing means in the stream. A square root extractor (20) and switching means (22) are also provided permitting the measurement and averaging of the square root of the velocity pressure measurement, i.e., velocity of the stream, by the device. The velocity pressure measurements or the square root thereof are exhibited on a first digital display (28) permitting the operator to monitor the measurements as they are taken. The measurements are subsequently averaged over a predetermined period of time by an arithmetic processor (18) and the resulting average is exhibited on a second digital display (30).

Preventive device for leakage of working fluid for axial-flow turbine and compressor

Abstract: PURPOSE:To inhibit the leakage current of a jet injected from one part of the nose of a movable vane by means of the pressure barrier of a casing wall by forming a taper in the axial direction to the casing wall so that the jet flows in the direction reverse to a component in the axial direction of the leakage current. CONSTITUTION:A fluid introduced into an internal flow path 2 of the movable vane 1 through a rotor is injected by pressure or centrifugal force from a nozzle 5 inclined in the direction opposing the leakage current 3, and flows along a tapered wall 4. The leakage current flowing along the casing wall to the low pressure side L from the high pressure side H or a stepped section of a turbine is prevented by the dynamic pressure of the current of the fluid.

Two methods for absolute calibration of dynamic pressure transducers

Abstract: Two techniques are described for absolute calibration of a dynamic pressure transducer from 0 to 400 Hz in 1‐MPa helium gas. One technique is based on a comparison to a mercury manometer; the other is based on the principle of reciprocity. The two techniques agree within the instrumental uncertainties of 1%.

Boundary layer controller in circular stream water tank

Abstract: PURPOSE:To improve distribution of flow speed in a boundary layer to desired distribution of flow speed, by detecting dynamic pressures in a boundary layer stream and general stream, accelerating the boundary layer stream and adjusting the both dynamic pressure values so as to be approximate. CONSTITUTION:Pitot tubes 9, 10 are provided in a general stream and boundary layer stream of a water line 2, then dynamic pressure P1 in the general stream, detected by the pitot tube 9, and dynamic pressure P2 in the boundary layer stream, detected by the piot tube 10, are compared by a pressure difference converter 11, and the boundary layer stream is accelerated by an accelerating means A so that a dynamic pressure value in the boundary layer stream may be approximated to a dynamic pressure value of the general stream. In this way, even if flow speed of the general stream is variously changed, distribution of flow speed in the boundary layer can be controlled to an otimum state promptly in accordance with that change.

Application of modal control to wing-flutter suppression

Abstract: A discrete modal control design approach that is applied to a single control surface, unswept aircraft wing subject to bending torsion flutter is described. The modal approach is a mathematical method to decouple the equations of motion into isolated differential equations. In this paper, a pole-placement approach is then applied to determine stability gains in the discrete plane using only the two complex-conjugate flutter-mode equations. A fixed gain Kalman filter is used to estimate the model amplitudes using three measurements. Results are presented for a full-state estimator (36 states) and two reduced state estimators using two different closed-loop pole locations. The control law is designed for a dynamic pressure that is 50 percent greater than the uncontrolled-flutter dynamic pressure. With constant control-law gains, the closed-loop system remains stable over the dynamic-pressure range from flutter onset to approximately an 80-percent increase in pressure.

Oil-pressure circuit for turning excavator

Abstract: PURPOSE:To reduce the loss of power by controlling the discharg rate of a variable pump to a minimum by using a system in which the pressure of drain when each operating valve is at neutral is taken out in dynamic pressure and NC valve is controlled by using its pilot pressure. CONSTITUTION:The discharge pressures of the first and second variable pumps 1 and 2 are supplied to turning valves 8 and 9, and when the turning valves 8 and 9 are at neutral, the discharge pressure of the first variable pump 1 is joined with that of the third variable pump 3 and the discharge pressure of the second variable pump 2 is joined with that of the fourth variable pump 4. Pressure detecctors 22 and 23 detect dynamic pressures, the spool of negative control valves 27, 28, 30, and 31 is pressed toward the left side, pressure oil supplied to servo mechanisms 1b-4b is drained, and the inclined angles of swash plates 1a-4a are controlled in such a way that the discharge amounts of the first the fourth variable pumps 1-4 are minimized.

Low-noise pressure reducing valve

Abstract: PURPOSE:To reduce the generation of noise, by attaining a reduction of pressure with a working mechanism that applies a working pressure to a bellows with the dynamic pressure of a fluid itself and giving a balance to the bellows so that it keep an opening appropriate to a flow. CONSTITUTION:A bellows 4 is provided at a port part to extend from a fixed end 10' and then presses with a free control the gap between the port part and a sheet part. when a working pressure having a relation of P1>P2>P3 is applied to the bellows 4, a downward force to press the port part down by the pressure P2 is applied to a pilot governor secondary room 19 through a tube 22. And a balance is obtained at a certain position between the push-up force and the push-down force. Both the balancing position and the working pressure P2 are decided by the primary side pressure P1 and the secondary side pressure P3 plus the flow rate of gas which flows at that moment. When the pressure P3 is higher than the set value, the pressure P2 becomes high to increase the force that pressed the port part down via the function of a pilot valve with which a part of the fluid works in division.

Turbine-driven rotor

Abstract: Turbine-driven rotor for use in motor vehicle engineering. Problem: petrol economy, improved acceleration, attainment of a higher output speed. The problem is solved by a rotor inside a fuse box, outside the body, which is in turn made to move by an exhaust gas-driven turbine. The dynamic pressure of the high-energy gases can be controlled by means of a bypass valve. In this way the dynamic pressure in the manifold can be varied. If the pressure increases, for example, due to corresponding spring tensioning of the bypass valve, the gases escape at a higher velocity along the turbine blades, thereby assisting the turbine to reach a higher number of revolutions, which in turn allows the rotor to run faster. With a certain forwards inclination the rotor has a spoiler-like effect, which occurs significantly earlier than with conventional spoilers. In this way the contact pressure and hence the road contact is discernibly improved right from the beginning. Principal potential application: motor vehicle construction, or vehicles producing exhaust gas.

An electronic circuit for regulating a dynamic pressure wave pneumatic control system

Abstract: A source of pressurized gas is attached to a dynamic pressure wave appliance. The pneumatic control circuit connects the source of pressurized gas to a first chamber of the appliance. When the pressure in the first chamber reaches a first predetermined level, a valve seals the first chamber and connects the source so as to inflate a second chamber about the first. When the pressure in the second chamber reaches a second predetermined level, a valve permits the first chamber to deflate while continuing to connect the second chamber for inflation. A valve for sealing the inflated sleeve discontinues the inflation of the sleeve when the pressure therein reaches a third predetermined level. The sequence of operation of the pneumatic control circuit will cause a suitable dynamic pressure wave appliance to apply a pressure to a human or animal extremity which begins at the most distant end and travels up the extremity in the nature of a pressure wave.

Dynamic pressure attenuator and method

Abstract: A dynamic pressure attenuator comprising a housing and a plurality of tubes extending through the interior of the housing and defining wind passages. Each of the tubes has a plurality of radially extending ports. The housing has an inlet to admit a gas to the interior of the housing. When wind passes through the wind passages, the static pressure in the ports is substantially normal ambient static pressure and the dynamic pressure in the ports is essentially zero. Gas from the inlet passes through the ports and the wind passages to the atmosphere.