Showing papers on "Dynamic pressure published in 1984"

Dynamic polymer pressure transducer with temperature compensation

Abstract: Accurate dynamic pressure data in a changing thermal environment is obtained through the use of a pressure gage formed from polyvinylidene fluoride (PVDF) polymer material. The temperature compensation pressure gage has three major elements: an active PVDF transducer which obtains remote pressure readings which are uncorrected for thermal effects; a thermocouple having a short rise time allowing an output thermal signal which dynamically responds to changing thermal conditions; and a compensation amplifier circuit receiving the uncorrected pressure readings and the dynamic thermal signal and producing an output signal representing accurate pressure data which is corrected for changing thermal conditions. Also disclosed are the details of making an active PVDF transducer.

Effects of the pressure perturbation field in numerical models of unidirectionally sheared thunderstorm convection - Two versus three dimensions

Abstract: The physical roles of 'buoyant' and 'dynamic' pressure components, and the distinction between buoyant and hydrostatic pressure perturbations, are aspects of the pressure perturbation field in strongly sheared convective storms studied by means of two- and three-dimensional anelastic numerical modeling experiments with common environmental profiles. The pressure analysis clarifies the differences between two- and three-dimensional storms. In the main updraft, strong midlevel thermal buoyancy is partly opposed by a downward-perturbed vertical pressure gradient force. This, however, occurs to a much greater extent in two dimensions than in three, contributing to smaller net upward accelerations. While the buoyant and hydrostatic fields are intimately related to the total buoyancy distribution, the buoyant pressure perturbation is smoother and of lower amplitude than its hydrostatic counterpart. For the model experiments, this distinction is far greater in three dimensions than in two, in association with the smaller scale of the active convection in three dimensions.

Flow measuring traverse probe

Abstract: A traverse probe for insertion transversely with respect to the direction of bulk flow of an air or gas stream to sense and average a traverse of the static pressure and separately to sense and average a traverse of the combination of static and velocity pressure or total pressure of the stream. The probe includes along its length a spaced set of total pressure ports in the tube wall substantially aligned with the direction of flow in the zone of positive total pressure at the tube wall facing the direction of flow and first and second spaced sets of static pressure ports in the tube wall, one set aligned in each of the zones of static pressure only that lie at the tube wall adjacent to and on each side of the zone of positive total pressure. The set of total pressure ports is aligned on the bisector of the included angle between the sets of static pressure ports where the included angle is in the range of about 78°-80° for useful probe diameters.

A Numerical Investigation of Mechanisms Linking Glaciation of the Ice-Phase to the Boundary Layer

Abstract: Nine clouds are simulated by perturbing Florida Area Cumulus Experiment (FACE) field soundings employing the Colorado State University cloud model. After a cloud similar in size to the one observed is initiated, glaciation is simulated in experiments designed to study the mechanisms by which glaciation is communicated to the subcloud boundary layer. Numerical model results show that the vertical pressure mechanism consisting of hydrostatic and dynamic pressure gradient force and “pressure buoyancy” is present, as is the downdraft mechanism, but they are secondary to loading, temperature buoyancy, water vapor buoyancy and the horizontal dynamic forces on the scale of a single deep convective cloud. The communication mechanism that has the most sustained and coherent influence upon the subcloud layer is the settling and evaporation of precipitation. A clear implication of this study to weather modification is that for dynamic seeding to have a significant influence upon the upscale growth of a clou...

Calculated effects of varying Reynolds Number and dynamic pressure on flexible wings at transonic speeds

Abstract: A computational method is described that includes the effects of static aeroelastic wing deflections in steady transonic aerodynamic calculations. This method, known as the Transonic Aero-elastic Program System (TAPS), interacts a 3D transonic computer code with boundary layer and a linear finite element structural analysis codes to calculate wing pressures and deflections. The nonlinear nature of the transonic flow makes it necessary to couple the aerodynamic and structures codes in an iterative manner. TAPS has been arranged in a modular fashion so that different aerodynamic or structures programs may be used with a minimum of coding changes required. Results obtained using two different aerodynamic codes in TAPS are given, and those results are correlated with experimental data.

Hydraulically controlled extruder injection molding units for the processing of rubber

Abstract: Disclosed is a hydraulically controlled extruder injection molding unit which includes a measured value pick-up for the position of the piston rod of the working cylinder and/or of the injection piston. A pressure control valve which can be switched on is provided in the line leading to the surge chamber of the working cylinder for the piston. A proportionally controlled pressure valve is provided in the line to the other surge chamber, the value being controlled as a function of dropping control values when switching from subsequent pressure to dynamic pressure until the measured value pick-up emits an output signal. The then existing instantaneous value of the dynamic pressure is then added to the preselected dynamic pressure. Consequently, the dynamic pressure phase takes place under a corrected dynamic pressure.

A Ventilation Design Program for Hand-Held Programmable Computers

Abstract: This computer program allows sizing and balancing of local exhaust ventilation branches and mains using the Velocity Pressure method as described in the ACGIH Industrial Ventilation Manual. The program is written in BASIC and is designed for use in any hand-held BASIC-programmable computer such as the Radio Shack TRS-80 Pocket Computer. The user enters branch design data and the program computes duct diameter, with an override option, actual velocity, duct velocity pressure, slot velocity pressure, hood static pressure and static pressure of each branch. It will compare branch static pressures and either identify a branch to be redesigned, or will correct the flow in the branch with lower static pressure, and will call for design data for the main. It concludes with a display of the total losses at the end of the main. A complete listing of the program and a worked-out example are given.

Carriage supporting device

Abstract: PURPOSE:To prevent the wear of a shaft hole by using dynamic pressure gas bearings and a static pressure gas bearings for supporting a carriage, and operating the static pressure gas bearings when the rotating speed of the shaft which constitutes one of the dynamic pressure gas bearings has assumed a predetermined value. CONSTITUTION:Air inlet ports for the static pressure gas bearing are provided in the carriage 3. These air inlet ports 17 communicate with minute gas between the shaft 7 and the support sleeves 6. The shaft 7 rotates by a driving motor 11, and the carriage 3 is driven in the direction of an arrow B while being supported by the dynamic pressure gas bearings when the shaft 7 is in a state of reaching a predetermined rotating speed. On the other hand, when the rotating speed of the shaft 7 is less than the predetermined value, the static pressure bearings are operated. That is, the rotating speed of the shaft 7 discriminates the rotating speed of the motor 11 by operating an air valve driving circuit, and compressed air is supplied from the air inlet ports 17 to the gaps between the shaft sleeves 6 and the shaft 7 to thereby support the carriage 3 by air pressure.

Static pressure automatic control device for closed circuit respirator

Abstract: A static pressure automatic control device for respirators of closed-circuit type comprises an exhaled air passage which is branched out of an exhalation system of a respirator and a static pressure discharge valve connected in series to this exhaled air passage. A respiratory dynamic pressure generated by exhalation is attenuated due to resistance encountered while the exhaled air is being passed through the exhaled air passage and substantially the static pressure only is applied to the discharge valve. When the static pressure exceeds a predetermined value, the discharge valve opens to let out a part of gas and thereby decreases the static pressure to the predetermined value.

A control volume based finite element method for solving the Navier-Stokes equations using equal order velocity-pressure interpolation

Abstract: A control volume-based finite-element method for solving the Navier-Stokes equations using equal-order velocity-pressure interpolation is presented. Unlike the unequal-order-type methods that compute pressure at much fewer grid points than velocity, the proposed equal-order method calculates velocity and pressure at all the grid points in the domain. The validity of the method is established by applying it to solve some test problems

Apparatus for measuring dynamic pressure of blower

Abstract: PURPOSE:To automate measurement and to enhance the accuracy of a measured value to achieve the rationalization in the capacity test of a blower 1 by a method wherein the pulse components of pressure measured by a multi-tubular Pitot tube are attenuated and further changed to a physical amount as well as averaged and the output signal thereof is inputted to perform treatment. CONSTITUTION:An arbitrary gate time is given to a pressure converter 5 from a treating apparatus 6. The physical amount (pressure vibration) variaed in said gate time is converted to frequency as the averaged physical amount [average pressure P'=DELTAtoPdt/DELTAt(gate time)] to be outputted to the treating apparatus 6 of a microcomputer B. In this case, a chamber 3, a change-over apparatus 4 and a pressure converter 5 constitutes a measuring part A. The above-mentioned apparatus 6 calculates the average value of one cycle (20 points dynamic pressure measurement) and further calculates the convergent ratio of dynamic pressure measured for several cycles and, by repeating the measurement of the aforementioned dynamic pressure until the dynamic pressure is brought to the range of a prescribed convergent ratio, preciseness enhancement can be achieved.

Evaluation of Dynamic Pressure due to Steam Condensation in Water and Multi-vent Effects

Abstract: An evaluation method for the dynamic pressure caused by steam condensation in such a large scale system as a BWR pressure suppression system has been developed. The pressure field obtained analytically in the pool has been coupled with that obtained in the vent pipes supposing the sources at the vent pipe exits. Both pressure fields in the vent pipes and in the pool are excited by applying the sources of impulsive nature to the vent pipe exits. The full scale test results performed at Japan Atomic Energy Research Institute have been simulated by the proposed method and agreement between experimental and calculated results is good. The so called multi-vent effects for the resultant dynamic pressure have been examined and the reduction effects for the dynamic pressure have been clarified. The dynamic pressure decreases in inverse proportion to an increase in the pool surface area.

Dynamic pressure log device for ships

Abstract: A dynamic pressure log to which is connected a device for electronic further processing and correction of the measured values is used to measure the speed of ships. The differential pressure measuring instrument (10) is arranged at the input (8) of a flow duct (7), the static and total pressure being measured approximately at the same location. The measured differential pressure is transmitted electrically to an adjusting unit (22), where it is converted into values corresponding approximately to the speed. These values are corrected in a following correction unit (23), e.g. in accordance with the flow conditions in the case of a circular course, or with the rudder position. The corrected speed value is displayed and used to calculate as a function of time the distance travelled and, as the case may be, to record the route travelled.

Dynamic pressure test unit-ratio method

Abstract: A dynamic pressure test unit is utilized to determine the yield point of alask. For a period of time prior to the yield point being reached the ratio of the pressure vs. volume of water pumped into a test flask assumes a constant value. After reaching the yield point the volume indication increases at a faster rate than the pressure giving a negative slope to a line on a stripchart recorder that indicates the pressure divided by the volume of water pumped into the flask.

Pressure detecting device

Abstract: PURPOSE:To improve responsiveness and to perform smooth control in a high load state by escaping part of pressure due to the flow rate component of inflow air. CONSTITUTION:A pressure conduit part 20 is constituted by forming plural small air inflow holes 22 in a hollow cylindrical body and then installing it oppositely to the side of a throttle 3. Then, one small air outflow hole 23 is formed in the opposite surface. In this case, the dynamic pressure from the inflow holes 22 is converted in the conduit part 20 into static pressure P, which is transmitted to a pressure sensor part, but air is reduced in pressure at the outside of the outflow hole 23 with an air flow running beside the conduit part 20, so part of the air flowing in the conduit part 20 flows out through the outflow hole 23 as shown by an arrow. Consequently, part of the dynamic pressure to be transmitted to the pressure sensor part is eliminated and high resolution is obtained over a wide range.

Similar Solutions of Gas Pressure Within Semi-infinite Capillary Tubes

Abstract: The similar solutions of Ducoffe's equation are presented. Through use of the solutions, the time variation of the gas pressure within thin semi-infinite capillary tubes is solved when the pressure at one end is changed discontinuously from an initial uniform value to a new constant one. The rate of pressure variation propagation decreases as the initial tube pressure becomes lower, and a finite velocity pressure variation front is formed if the initial tube pressure is a vacuum. Very close to the open end, the order of the propagation rate is reversed.

Investigation of the external flow analysis for density measurements at high altitude

Abstract: The results of analysis performed on the external flow around the shuttle orbiter nose regions at the Shuttle Upper Atmosphere Mass Spectrometer (SUMS) inlet orifice are presented. The purpose of the analysis is to quantitatively characterize the flow conditions to facilitate SUMS flight data reduction and subsequent determination of orbiter aerodynamic force coefficients in the hypersonic rarefied flow regime. Experimental determination of aerodynamic force coefficients requires accurate simultaneous measurement of forces (or acceleration) and dynamic pressure along with independent knowledge of density and velocity. The SUMS provides independent measurement of dynamic pressure; however, it does so indirectly and requires knowledge of the relationship between measured orifice conditions and the dynamic pressure which can only be determined on the basis of molecule or theory for a winged configuration. Monte Carlo direct simulation computer codes were developed for both the flow field solution at the orifice and for the internal orifice flow. These codes were used to study issues associated with geometric modeling of the orbiter nose geometry and the modeling of intermolecular collisions including rotational energy exchange and a preliminary analysis of vibrational excitation and dissociation effects. Data obtained from preliminary simulation runs are presented.