Showing papers on "Pressure measurement published in 2002"

Barometric pressure correction based on remote sources of information

Abstract: The invention includes systems and methods for converting absolute pressure data acquired in anatomical environments to gauge pressure data using an implant configured to monitor pressure. The implant is configured to communicate with an external controller, which is configured to communicate with a remote microprocessor that includes real-time barometric pressure data for one or more geographic locations.

Transient Flow in a Rapidly Filling Horizontal Pipe Containing Trapped Air

Abstract: The pressure within a trapped air pocket in a rapidly filling horizontal pipe is investigated both experimentally and analytically. The downstream end of the pipe is either sealed to form a dead end or outfitted with an orifice to study the effects of air leakage on the pressure. Three types of pressure oscillation patterns are observed, depending on the size of the orifice. When no air is released or orifice sizes are small, the cushioning effects of the air pocket prevents the water column from impacting on the pipe end and from generating high water hammer pressures. However, the maximum pressure experienced may still be several times the upstream driving pressure. When the orifice size is very large, the air cushioning effect vanishes and the water hammer pressure is dominant. For intermediate orifice sizes, the pressure oscillation pattern consists of both long-period oscillations (while the air pocket persists) followed by short-period pressure oscillations (once water hammer pressures dominate). Air leakage is observed to play a significant role in increasing the magnitude of the observed pressures during rapid filling, resulting in peak pressures up to 15 times the upstream head. An analytical model, capable of calculating the air pocket pressure and the peak pressure when the water column slams into the end of the pipe, is developed and results are compared with those of experiments. The model was successful in determining the amplitude of the peak pressure for the entire orifice range and was able to simulate the pressure oscillation pattern for the case of a negligible water hammer impact effect. Although the model was unable to simulate the pressure oscillation pattern for substantial air release, it was able to predict the type of pressure oscillation behavior and the peak pressure.

Multiple-arrayed pressure measurement for investigation of the unsteady flow structure of a reattaching shear layer

Abstract: Spatio-temporal characteristics of wall pressure fluctuations in separated and reattaching flows over a backward-facing step were investigated through an extensive pressure-velocity joint measurement with an array of microphones. The experiment was performed in a wind tunnel with a Reynolds number of 33 000 based on the step height and the free-stream velocity. Synchronized wavelet maps showed the evolutionary behaviour of pressure fluctuations and gave further insight into the modulated nature of large-scale vortical structures. To see the relationship between the flow eld and the relevant spatial mode of the pressure eld, a new kind of wavenumber ltering, termed ‘spatial box ltering’ (SBF), was introduced and examined. The vortical flow eld was reconstructed using every single-point velocity measurement by means of the conditional average based on the SBF second mode of pressure fluctuations. The flow eld showed a well-organized spanwise vortical structure convected with a speed of 0:6U0 and a characteristic ‘sawtooth’ pattern of the unsteady trace of reattachment length. In addition to the coherent vortical structures, the periodic enlargement/shrinkage process of the recirculation region owing to flapping motion was analysed. The recirculation region was found to undergo an enlargement/shrinkage cycle in accordance with the lowpass-ltered component of pressure fluctuations. In addition, such modulatory behaviour of the vortical structure as the global oscillation phase was discussed in connection with the conditionally averaged flow eld.

A monolithic fully-integrated vacuum-sealed CMOS pressure sensor

Abstract: This paper presents an integrated multi-transducer capacitive barometric pressure sensor that is vacuum-sealed at wafer level. The interface circuitry is integrated directly within the sealed reference cavity, making the device immune to parasitic environmental effects. The overall device process merges CMOS circuitry with a dissolved-wafer transducer process and is compatible with bulk- and surface-micromachined transducers. The process employs chemical-mechanical polishing (CMP), anodic bonding, and hermetic lead transfers. The sensor achieves 25 mtorr resolution and is suitable for low-cost packaging. It is composed of a programmable switched-capacitor (SC) readout circuit, five segmented-range pressure transducers, and a reference capacitor, all integrated on a 6.5/spl times/7.5 mm/sup 2/ die using 3 /spl mu/m features.

Equation of state of bismuth to 222 GPa and comparison of gold and platinum pressure scales to 145 GPa

Abstract: Unit cell volumes of Bi, Pt, and Au have been measured simultaneously to megabar pressures by x-ray powder diffraction using a diamond anvil cell and a synchrotron radiation source. The body-centered cubic (bcc) phase of Bi was found to be stable up to 222 GPa. The equation of state (EoS) of bcc-Bi was determined using the Pt pressure scale. A fit of the Vinet EoS to the volume compression data gave B0=35.22(19) GPa, B0′=6.303(18), and 1 atm atomic volume V0=31.60(4) A3. Because of the high compressibility, the use of bcc-Bi as a pressure marker is expected to give improved precision in pressure measurement. The Pt and Au pressure scales were compared up to 145 GPa. The Au pressure scale gave lower pressure than the Pt pressure scale. The deviation between the two scales became noticeable at ∼30 GPa and diverged with increasing pressure, reaching ∼20 GPa at 145 GPa. A fit of the Vinet EoS to Au compression data on the Pt pressure scale gave: B0=166.34(77) GPa, and B0′=6.244(33).

Can a clinically useful aortic pressure wave be derived from a radial pressure wave

Abstract: Background The information contained in arterial pressure waveforms is probably underused by most clinicians who manage critically ill patients. It is not generally known that an aortic pressure wave can be synthesized by applying a generalized transfer function to the radial arterial pressure wave. We validated a commercially available system, SphygmoCor™ (PWV Medical, Sydney). Methods Ascending aortic pressure waves were synthesized and comparisons were made between the synthesized aortic waveforms, the measured aortic and radial arterial waveforms. Ascending aortic pressure waves (catheter-tip manometer) and radial artery pressure waves (short fluid-filled catheter) were recorded simultaneously in 12 patients with angina pectoris (age 62–76 years) undergoing cardiac catheterization. Patients were studied at rest, following midazolam, sublingual nitroglycerin and during Valsalva manoeuvres. Results Both midazolam and nitroglycerin lowered mean arterial pressure but nitroglycerin caused a more selective decrease in the measured and synthesized aortic systolic pressures than in the radial artery pressure. The synthesized aortic systolic pressure was less, by 6–8 mm Hg ( sd 2–3) and the synthesized aortic diastolic pressure greater, by 4 mm Hg ( sd 2). Despite these differences in pulse pressure, the synthesized waveform tracked the measured waveform before and during interventions. Conclusions By deriving an aortic waveform from the radial pulse, monitoring of left ventricular afterload can improve without more invasive means.

Method for processing information in a tire pressure monitoring system

Abstract: A method of processing information in a tire pressure monitoring system includes the steps of: establishing a reference temperature; determining a pressure warning threshold at the reference temperature; measuring gauge pressure and gauge temperature within a tire cavity; correcting the gauge pressure to a filtered pressure value at the reference temperature using the Ideal Gas Law; and comparing the filtered pressure value against the pressure warning threshold to determine the necessity for a warning signal. In an advanced form of the invention, the method includes determining a pressure leak rate; predicting the time interval that the filtered pressure value will cross the pressure warning threshold at the leak rate and generating progressive warnings to the driver over the time interval. Fuzzy logic is used to quantify the probability of a warning state for each data point, allow for measurement error; and report the state of maximum probability to minimize the occurrence of false warning. A warning utility function is derived based upon a combination of the filtered pressure and leak rate.

Liquids Under Negative Pressure

Abstract: Introduction. Photograph of the participants. Participants. Part I: Stability, metastability and instability. Limits of stability for liquids under tension R.J. Speedy. Limiting superheat of aqueous solutions at negative pressures V.E. Vinogradov, P.A. Pavlov. Classical thermodynamics of states with negative absolute temperature or with negative absolute pressure K. Martinas, A.R. Imre. Limiting tensions for liquids and glasses from laboratory and MD studies Q. Zheng, et al. Investigation of the thermodynamic properties of a polarizable water model in a wide range of pressures around the temperature of maximum density P. Jedlovsky, R. Vallauri. Part II: Physical chemistry of liquids under negative pressure. Water at positive and negative pressures H.E. Stanley, et al. The thermophysical properties of liquids on the melting line at negative pressures M. Faizullin, V.P. Skripov. Liquid-liquid phase equilibria in binary mixtures under negative pressure A.R. Imre. Measuring the properties of liquids and liquid mixtures at absolute negative pressures L.P.N. Rebelo, et al. Limiting tensile strength of capillary-condensed liquids W.D. Machin. On the tricritical point of the isotropic-nematic transition in a rod-like mesogen hidden in the negative pressure region S.J. Rzoska, A. Drozd-Rzoska. Part III: Negative pressure and solidification. Negative pressure development during crystalization of polymers A. Galeski, E. Piorkowska. Cavitation during isothermal crystallization of isotactic polypropylene and poly(methylene oxide) E. Piorkowska, R. Nowacki. Part IV: Helium under negative pressure. The limits of metastability of liquid helium S. Balibar, F. Caupin. Cavitation in 3He-4He liquid mixtures M. Barranco,et al. A Quantum Monte Carlo study of the negative pressure regime in quantum liquids J. Boronat, J. Casulleras. Nucleation of bubbles on electrons in liquid helium H.J. Maris, D. Konstantinov. Quantum statistics of metastable liquid helium F. Caupin, S. Balibar. Part V: Cavitation during static and dynamic tensions. Acoustic cavitation thresholds of ocean water V.A. Akulichev. Cavitation in liquids by classical nucleation theory and molecular dynamics simulations C. Xiao, et al. A study of cavitation phenomena using an atomic force microscope M.S. Barrow, et al. Cavitation thresholds, free surface and cavity cluster dynamics in liquids at shock wave reflection A. Besov, et al. Relaxation effects and disintegration problems of cavitating liquids at pulse loading V.K. Kedrinskii. Measurement of the cavitation threshold of liquids under dynamic stressing by pulses of tension P.R. Williams, R.L. Williams. Negative pressure tail of a reflected pressure pulse: A lattice-Boltzmann study G. Hazi, A.R. Imre. Ultrasonic cavitation in freon at room temperature F. Caupin, V. Fourmond. Part VI: Heterogeneous nucleation. Dependence on kinds of impurity gases in metals of negative pressures in water/metal Berhelot tube systems Y. Ohde, Y. Tanzawa. Heterogeneous nucleation, influence of heterophase fluctuations on the cavitation strength, and the supercooling of liquids with phase inclusions V.A. Bulanov.

CFD calculation of a mixed flow pump characteristic from shutoff to maximum flow

Abstract: The behavior of the flow in a vertical semi-axial mixed flow pump has been analyzed by numerical flow simulations of the entire stage, and the results have been compared to test data. As the flow is expected to be unsteady at part load in such a pump, the steady-state simulations were complemented with unsteady flow simulations of the entire machine at one part load operating point. Pressure measurements at different locations in the casing of the pump provided valuable data for the validation of the calculated pressure head. This paper shows that the pump characteristic can be quite accurately predicted from full load to part load by modern numerical tools. Simulations of the unsteady flow which use much more computer resources, are also feasible in an industrial environment and yield detailed information about the flow patterns and pressure fluctuations in the pump.

Tire pressure monitoring system with pressure gauge operating mode for indicating when air pressure within a tire is within a predetermined pressure range

Abstract: A tire inflation pressure monitoring system (10) and a method for monitoring air pressure within a tire (14) are provided. The system (10) includes a tire based unit (18) for sensing air pressure within the tire (14) and for transmitting a pressure signal indicative thereof. The system (10) also includes a vehicle based unit (16) for receiving the pressure signal and for comparing the pressure signal to a predefined pressure range. The vehicle based unit (16) is operable in one of (i) a normal operating mode that outputs an alert signal in response to the air pressure within the tire (14) being outside of the predefined pressure range and (ii) a pressure gauge operating mode that outputs an in-range signal in response to the air pressure within the tire (14) being within the predetermined pressure range.

Simultaneous measurement of down-hole high pressure and temperature with a bulk-modulus and FBG sensor

Abstract: A free active element bulk-modulus-based fiber Bragg grating (FBG) sensor for down-hole pressure and temperature measurement is presented. With a differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped-signal in FBG sensors are solved. Simulation results indicate that the measurement sensitivity in measuring pressure and temperature is estimated to be /spl sim/8.5 pm/MPa in a range from standard atmosphere pressure to 100 MPa and /spl sim/27.5 pm//spl deg/C from 20 to 200/spl deg/C, respectively.

High-Temperature, High Bandwidth, Fiber-Optic, MEMS Pressure Sensor Technology for Turbine Engine Component Testing

Abstract: Acquiring accurate, transient measurements in harsh environments has always pushed the limits of available measurement technology. Until recently, the technology to directly measure certain properties in extremely high temperature environments has not existed. Advancements in optical measurement technology have led to the development of measurement techniques for pressure, temperature, acceleration, skin friction, etc. using extrinsic Fabry-Perot interferometry (EFPI). The basic operating principle behind EFPI enables the development of sensors that can operate in the harsh conditions associated with turbine engines, high-speed combustors, and other aerospace propulsion applications where the flow environment is dominated by high frequency pressure and temperature variations caused by combustion instabilities, blade-row interactions, and unsteady aerodynamic phenomena. Using micromachining technology, these sensors are quite small and therefore ideal for applications where restricted space or minimal measurement interference is a consideration. In order to help demonstrate the general functionality of this measurement technology, sensors and signal processing electronics currently under development by Luna Innovations were used to acquire point measurements during testing of a transonic fan in the Compressor Research Facility (CRF) at the Turbine Engine Research Center (TERC), WPAFB. Acquiring pressure measurements at the surface of the casing wall provides data that are useful in understanding the effects of pressure fluctuations on the operation and lifetime wear of a fan. This measurement technique is useful in both test rig applications and in operating engines where lifetime wear characterization is important. The measurements acquired during this test also assisted in the continuing development of this technology for higher temperature environments by providing proof-of-concept data for sensors based on advanced microfabrication and optical techniques.

Miniature fiber optic pressure sensor for medical applications

Abstract: Presents a theoretical description, fabrication and experimental investigation of miniature optical fiber pressure sensor for invasive measurement of blood pressure. Sensor measures only 125 /spl mu/m in diameter. The essential element is thin polymer diaphragm that is positioned inside a hollow end of the optical fiber. The cavity at the fiber end is made by wet etching in diluted HF acid. Thus the Fabry-Perot interferometer is formed between the inner fiber-cavity interface and the diaphragm. Deflection of the diaphragm and so pressure magnitude is determined by reading the reflectance spectrum of the sensing Fabry-Perot interferometer using broadband illumination. The configuration of Fabry-Perot interferometer at the optical fiber end makes sensor immune from bending of optical fiber and optical power fluctuations of light source. We deployed sensor prototype from 125 /spl mu/m-diameter optical fiber. It is optimized for human blood pressure range, namely from 0 to 40 kPa (0 to 300 mmHg) with 1 mmHg resolution. Our fabrication technique offers simple and low-cost disposable medical pressure sensor production.

Characteristics of Argon Laminar DC Plasma Jet at Atmospheric Pressure

Abstract: Argon DC plasma jets in stable laminar flow were generated at atmospheric pressure with a specially designed torch under carefully balanced generating conditions. Compared with turbulent jets of short length with expanded radial appearance and high working noise, the laminar jet could be 550 mm in length with almost unchanged diameter along the whole length and very low noise. At gas feeding rate of 120 cm3/s, the jet length increases with increasing arc current in the range of 70–200 A, and thermal efficiency decreases slightly at first and then leveled off. With increasing gas flow rate, thermal efficiency of the laminar jets increases and could reach about 40%, when the arc current is kept at 200 A. Gauge pressure distributions of the jets impinging on a flat plate were measured. The maximum gauge pressure value of a laminar jet at low gas feeding rate is much lower than that of a turbulent jet. The low pressure acting on the material surface is favorable for surface cladding of metals, whereas the high pressure associated with turbulent jets will break down the melt pool.

Assessment of Particle Suspension Conditions in Stirred Vessels by Means of Pressure Gauge Technique

Abstract: In this work the quantitative assessment of the mass of suspended solid particles in stirred vessels is performed using the Pressure Gauge Technique. This is based on the measurements of the pressure increase on the tank bottom due to the presence of suspended solid particles at any agitation speed. The method has the advantages of not utilising visual observations and of easy and inexpensive application to both laboratory and industrial equipment. Very few data are available in literature and the experimental results collected using the present PGT technique and the correlations here proposed are of considerable academic and industrial interest.

Low pressure measurement devices in high pressure environments

Abstract: The present invention presents various novel approaches to solving the problems inherent in measuring biological pressures in high pressure systems. Thus, to protect a pressure transducer exposed to fluid flows at higher pressures than its overpressure rating, a novel valve is used that closes a protected leg in which the transducer is located. The various exemplary embodiments of such valves each have a high pressure input, one or more low pressure inputs, and an output. In operation, when a high pressure fluid flow occurs at a high pressure input, such valves automatically close the low pressure inputs. Alternatively, a novel transducer system is presented, which automatically limits the effective pressure sensed by a transducer to a certain maximum.

Pressure sensor, pressure measuring apparatus, and pressure measurement system using them

Abstract: PROBLEM TO BE SOLVED: To provide a pressure measurement system using a pressure detection sensor that has a simple configuration and is inexpensive and a pressure measuring apparatus. SOLUTION: The pressure measurement system 1 comprises the pressure sensors 50a-50d and the pressure measuring apparatus 10. The pressure sensors 50a-50d are composed as a radio tag having a resonance circuit, where a resonance frequency changes depending on pressure. The pressure measuring apparatus 10 detects the resonance frequency of the resonance circuit and specifies the pressure of the radio tag, based on the detected resonance frequency, by transmitting or receiving radio waves to and from the pressure sensors 50a-50d. COPYRIGHT: (C)2004,JPO

Pressure loss in constriction microchannels

Abstract: Constriction devices contain elements inserted into the fluid stream, which change the local streamwise flow area. One such element is the orifice-like obstruction with sharp corners, a back-to-back abrupt contraction and expansion, which could trigger flow separation. A series of microchannels, 40 /spl mu/m /spl times/ 1 /spl mu/m /spl times/ 4000 /spl mu/m in nominal dimensions, with constriction elements at the centers of the channels has been fabricated using standard micromachining techniques. The channel widths at the constriction sections varied from 10 /spl mu/m to 34 /spl mu/m, with pressure sensors integrated in each channel. Nitrogen gas was passed through the microdevices under inlet pressure up to 50 psi. The mass flow rates were measured for all the devices as a function of the pressure drop. A monotonic decrease of the flow rate with decreasing constriction-gap width was observed. The pressure distribution along the microchannel with the smallest constriction gap showed a pressure drop across the constriction element. Both mass flow rate and pressure measurements indicate that flow separation from the constriction sharp corners could occur.

Direct measurement of intratracheal pressure in pediatric respiratory monitoring

Abstract: We describe a method based on a Fabry-Perot interferometer at the tip of an optic fiber with a diameter of 0.25 mm for direct measurement of tracheal pressure in pediatric respiratory monitoring. The response time of the pressure transducer and its influence on the resistance of pediatric endotracheal tubes (internal diameter, 2.5 to 5 mm) during constant and dynamic flow at different ventilator settings in a lung model were measured. The transducer was positioned at -1.5 (inside), 0, and +1.5 cm (outside) relative to the tip of the endotracheal tube and compared with a reference pressure inside the trachea. The clinical application of the transducer was tested in five pediatric patients. The response time of the transducer was 1.3 ms. The influence of the fiberoptic transducer on tube resistance was negligible during constant flow in inspiratory and expiratory directions for all endotracheal tubes tested. There was no difference in pressure measurements with the transducer positioned at or 1.5 cm below or above the tip of the endotracheal tube during dynamic measurements. During clinical circumstances insertion of the fiberoptic transducer was easy, recordings were stable, and the safety of the patient was not jeopardized. The fiberoptic transducer provided a reliable and promising way of monitoring tracheal pressure in intubated pediatric patients. The presence of the probe did not interfere with either pressure-flow relationship or patient care and safety. The technique is proposed for monitoring of respiratory mechanics and calculation of changes in tube resistance caused by kinking and secretions.

Measuring interface pressure: a laboratory-based investigation into the effects of repositioning and sitting.

Abstract: Measurement of interface (or contact) pressure is important in assessing tissue viability in relation to pressure sore prevention and may be achieved through pressure mapping techniques. This article reports on two pilot studies using the Force Sensing Array pressure mapping system in a laboratory setting. The purpose of Study 1 was to examine the consistency of readings from the system across 1-min trials of repositioning, and Study 2 aimed to investigate changes in interface readings over a 20-min sitting period. Analyses on measurements of average pressure (mean of all sensor values) and maximum pressure (highest individual sensor value) were performed using the t test and repeated-measures analysis of variance. The results demonstrated that the use of average and maximum pressure measurements reflected only low reliability and that 6 min was likely to be the optimal sitting time required before stable pressure measurement. However, because of the limitations of using small convenience samples of healthy participants (n = 44 for Study 1, n = 20 for Study 2), these studies should be replicated with larger samples of healthy participants and then verified with disabled populations before adoption into clinical practice.

Predicting membrane oxygenator pressure drop using computational fluid dynamics.

Abstract: Three-dimensional computational fluid dynamic (CFD) simulations of membrane oxygenators should allow prediction of spatially dependent variables and subsequent shape optimization. Fiber bed complexity and current computational limitations require the use of approximate models to predict fiber drag effects in complete device simulations. A membrane oxygenator was modified to allow pressure measurement along the fiber bundle in all cardinal axes. Experimental pressure drop information with water perfusion was used to calculate the permeability of the fiber bundle. A three-dimensional CFD model of a commercial membrane oxygenator was developed to predict pressure drops throughout the device. Darcy's Law was used to account for the viscous drag of the fibers and was incorporated as a momentum loss term in the conservation equations. Close agreement was shown between experimental and simulated pressure drops at lower flow rates, but the simulated pressure drops were lower than experimental results at higher flows. Alternate models of fiber drag effects and flow field visualization are suggested as means to potentially improve the accuracy of the flow simulation. Computational techniques coupled with experimental verification offer insight into model validity and show promise for the development of accurate three-dimensional simulations of membrane oxygenators.

Absolute pressure sensor

Abstract: A barometric pressure sensor including a base layer, a sensor layer and a reference layer. The base layer has a passageway between a pressure inlet and a mounting face. The sensor layer is bonded by an insulating bond to the mounting face and includes a conductive diaphragm. The reference layer is mounted on the sensor layer to form a reference vacuum cavity. The reference layer includes a conducting surface facing the conductive diaphragm across the reference vacuum cavity to form a pressure sensing capacitor.

Unsteady Pressure Measurements in Turbomachinery using Porous Pressure Sensitive Paint

Abstract: This work demonstrates the capability of porous pressure sensitive paint (porous PSP) to make full unsteady surface pressure measurements in rotating turbomachinery. Response time calibrations with shock tube and oscillating jet experiments show that porous PSP responds to pressure fluctuations as fast as 40 kHz. Porous PSP is used in this work to measure the unsteady pressure fluctuations on the wall of a turbocharger compressor inlet. The blade passage frequency of the compressor ranges up to 10 kHz. This paper also demonstrates the use of PSP on thin turbomachinery components where it is difficult to apply conventional instrumentation. Porous PSP is applied to the blade, measuring only 0.027" thick, for global blade pressure measurements that are steady in the rotating frame. Porous Polymer/Ceramic PSP is used for these tests and demonstrates good adhesion characteristics to rotating parts.

Comparison between the Au and MgO pressure calibration standards at high temperature

Abstract: [1] We compare the MgO pressure scales previously developed using molecular dynamics simulations based on empirical and non-empirical interatomic potentials, to check the accuracy of the reported pressure scales at high temperatures. We find excellent agreement between the two independent pressure scales over wide temperature and pressure ranges, with simulated pressure discrepancies between the two for specified relative volumes being within 0.5 GPa in the temperature and pressure ranges up to 2000 K and 30 GPa. Based on recent simultaneous pressure measurements using both the MgO and Au scales with a multi-anvil apparatus at 1873 K, we then compare the resulting pressures based on the MgO scale with those based on the Anderson's Au scale, which is recently widely used to estimate pressures in high temperature and high pressure experiments. We find the Andrerson's Au scale underestimates pressures by 1.4 ± 0.3 GPa relative to the MgO scale at 1873 K.

Turbine Tip and Shroud Heat Transfer and Loading: Part A — Parameter Effects Including Reynolds Number, Pressure Ratio, and Gas to Metal Temperature Ratio

Abstract: Turbine tip and shroud flow and heat transfer are some of the most complex, yet important, issues in turbine design. Most of the work performed to date has been performed in linear cascades and has investigated such items as the effect of tip geometries and turbulence on tip and shroud pressure and heat transfer. There have been very few full annulus or rotating measurements in the literature. Experimental measurements have been made on a single stage high pressure turbine at the US Air Force Turbine Research Facility (TRF) to aid in the understanding of this phenomena. The TRF is a full scale, rotating rig that operates at matched flow conditions to the true turbine environment. Heat flux measurements were acquired with both Pyrex insert strip and button gauges while the pressure measurements were taken with surface mounted Kulite® pressure transducers. This paper presents one of the first full rotating, simultaneous pressure and heat transfer measurements to be taken in the turbine tip shroud region. These measurements provide some of the details needed for accurately quantifying the true flow condition in this complex flow regime. Comparisons between the present data and the existing 2D cascade data were made. This investigation quantified the effects of Reynolds number, inlet temperature, turbine pressure ratio and inlet flow temperature profiles. This provides a benchmark data set for validation of numerical codes.Copyright © 2002 by ASME

Assembly of tire and rim

Abstract: An assembly of a tire and a rim allowing a stable running over a required distance even if a tire internal pressure is lowered after the tire gets damaged without sacrificing a rolling resistance and a riding comfortableness in normal running before the tire gets a damage, wherein the hollow donut-shaped tire is installed on an applicable rim, a large number of generally spherical particles formed of resin of continuous phase and independent bubbles and having an average bulk specific gravity under the atmospheric pressure of 0.1 or less are disposed in the tire partitioned by the tire and the applicable rim, and a pressure inside the tire at the temperature of 25 °C is set to 150 kPa or higher in absolute pressure.

In-situ Pressure Measurements Using Raman Microspectroscopy in a Rolling Elastohydrodynamic Contact

Abstract: The physical conditions (pressure, shear stress, temperature) generated in an elastohydrodynamic (EHD) contact are the main parameters governing the evolution of the physico-chemical properties of the lubricant within the contact. This paper presents insitu measurements of pressure in an EHD point contact using Raman microspectroscopy. Two model lubricants are studied: a pure polyphenyl ether (5P4E) oil and a mixture of this oil with a liquid crystal. The influence of load and speed on the pressure distributions is investigated. The Petrusevich pressure spike is measured and its evolution with the operating parameters is in good agreement with the theoretical predictions. The addition of the liquid crystal to the base oil leads to an important diminution of the mixture viscosity, and consequently of the film thickness in the contact. The different rheological properties of the lubricants induce significant variations of the pressure profiles.

Manganin Gauge and Reactive Flow Modeling Study of the Shock Initiation of PBX 9501

Abstract: A series of 101mm diameter gas gun experiments was fired using manganin pressure gauges embedded in the HMX‐based explosive PBX 9501 at initial temperatures of 20°C and 50°C. Flyer plate impact velocities were chosen to produce impact pressure levels in PBX 9501 at which the growth of explosive reaction preceding detonation was measured on most of the gauges and detonation pressure profiles were recorded on some of the gauges placed deepest into the explosive targets. All measured pressure histories for initial temperatures of 25°C and 50°C were essentially identical. Measured run distances to detonation at three input shock pressures agreed with previous results. An existing Ignition and Growth reactive flow computer model for shock initiation and detonation of PBX 9501, which was developed based on LANL embedded particle velocity gauge data, was tested on these pressure gauge results. The agreement was excellent, indicating that the embedded pressure and particle velocity gauge techniques yielded consistent results.