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Research is conducted to examine symmetrically heated parallel-plate channels with a series of transverse V-grooves formed in both walls. Channel Reynolds number is used to characterize the flow rate in two open-circuit flow channels under consideration. Experimental results reveal that air flows in symmetrically V-grooved channels become fully developed and the fully developed property of the flow is maintained to the last groove-pair in the series.

A flowfield velocity and pressure measurement probe with an almost omnidirectional velocity measurement features is developed for three-velocity-component and pressure measurements that centers on the methods used in probe fabrication, calibration, and frequency-response research. The probe tip is a sphere with 18- pressure-port spherical head evenly distributed over the surface. The design and construction of the probe and its calibration for use in compressible flows are discussed.

The relationship between the emission intensity of xenon iodide excimers was investigated by using dielectric barrier discharge at high pressures. The results revealed that a half width of the B1/2-X1/2 transition from the de-exciting XeI* excimers was reduced when the total pressure was increased, whereas the intensity increased in direct proportion to intensity within the pressure range 100-150 mbar. However, the ultraviolet intensity was reduced as the gas pressure increased beyond 500 mbar.

An automated system can accurately determine partial pressures of oxygen, carbon dioxide and nitrogen in surface waters. A programmable data logger-controller, an infrared CO2 analyzer, a polarographic O2 electrode, and a barometer connected to a submersed gas exchanger made of thin-walled silicone elastomer tubing are used. Metabolic and gas flux studies can be made even in highly oligotrophic waters. Data from a small oligotrophic lake provide evidence of epilimnetic supersaturation.

Comparison of predicted with observed attenuation of pressure fluctuations shows that wave heights can be estimated with observations from a pressure sensor that is buried a known depth in fine sand. The attenuation of pressure fluctuations within the sand bed under unbroken shoaling waves, bores in the surf zone, and swash near the shoreline was measured with vertical stacks of buried pressure sensors. The attenuation increased with increasing frequency and depth below the bed surface, consistent with previous observations under nonbreaking waves in deeper water and with model predictions based on poro-elastic theory. In the limit of an infinitely deep soil skeleton that is much more compressible than the pore fluid, the predicted pressure fluctuations decrease exponentially with increasing burial depth, and the attenuation is independent of the sediment properties. For the fine-grained sand beds considered here, this exponential limit accurately predicts the observed attenuation.

The dynamic characteristics of fluctuating pressure measuring systems composed of connection tubing and pressure transducers were analyzed. A method of correction for the effects of resonance and viscous damping on the measured pressure fluctuations was proposed. A mathematical model of the measuring system was formed combining the governing equations of the unsteady flow in the rigid connection tubing and the corresponding volumetric deformation in the transducer. Numerical solution of the governing equations were described. The phase shift between the velocity amplitude on the tube axis and the maximum wall shear stress was obtained from numerical solutions for a wide frequency range of sinusoidal pressure variations. Amplification and attenuation of sinusoidal pressure variations were given in terms of dimensionless parameters. An in situ dynamic calibration to obtain lumped compliance of the measuring system was described. The method was applied to correct the measured pressure fluctuations obtained from different sources. The mathematical and numerical model was successful in correcting amplification and attenuation occurring on different frequency bands of the same pressure record with random fluctuations.

The circulation pattern in the South Atlantic was studied using a sigma-coordinate primitive equation model to elucidate two issues associated with sigma-coordinate, namely diffusion of heat and salt and pressure gradient computation. The deviation in the salinity and temperature fields caused by an iso-sigma diffusion mechanism was found substantial, thereby resulting in illogical velocity values. Thus, the diffusion along sigma surfaces was not suitable for applications involving general circulation problems.

Measurements were made on the metal axial acceleration and interface velocity of impedance-matching salt crystals using Fabry-Perot laser interferometry by detonating triaminotrinitrobenzene (TATB)-based charges. The ultrafine TATB became the bases for the investigation of the von Neumann spike state, reaction rates and the reaction product equation of state in the ignition and growth detonation reactive flow model. The data derived were found consistent with other estimates for carbon-rich explosives, which took account of the carbon condensation processes.

The use of aluminum-in-hornblende (AH) barometry to evaluate the tilt of the Mount Stuart batholith is feasible because of the positive correlation between the total aluminum content of hornblende and equilibration pressure. Critics dispute that the AH estimates would apply only if emplacement temperatures are procured for all existing samples and if differences in temperature range do not exceed 4 kbar.

The design parameters in sands were determined using the cone pressuremeter. Results were interpreted by employing a theory that incorporates the major aspects of sand behavior around an expanding cavity. Results show that the cone pressuremeter and the theory may be effectively applied for friction angle and initial state parameter estimation. Additional efforts, however, should be conducted to ensure that test data differences are caused by soil behavior and not test procedures and equipment properties.

A series of dilatometer test profiles were carried out in a calibration chamber on Toyoura sand using a standard blade and a special research dilatometer. Pluviated sand samples were prepared using various combinations of boundary conditions, relative density, and stress history. The research dilatometer probe consists of a standard blade modified internally to allow monitoring of the complete pressure-displacement soil response during a test. Precise performance of small unload-reload cycles can also be performed to evaluate elastic deformation properties. The pressure-displacement response during the expansion tests clearly shows the influence of stress history and density. The stiffness of the Toyoura sand from both dilatometers were also compared to that measured in laboratory monotonic shear tests and to various empirical relationships. The results suggest that the moduli measured from the unload-reload cycles during the research dilatometer tests reflect the elastic properties of the soil and can be correlated to results from resonant column tests and monotonic torsional shear tests. Modulus values measured with the standard dilatometer are more representative of an elasto-plastic response.

The luminescence of a pressure sensitive paint formulation consisting of a luminescent polypyridine ruthenium(II) dye dispersed in polydimethysiloxane binder exhibits temperature dependence effects. The intrinsic temperature dependence of the nonradiative decay rate of the luminescent probe molecule effects the temperature dependence of emission intensity and decay lifetime. The effect occurs under deoxygenated conditions. Temperature dependence of oxygen diffusivity in the polymer matrix effects the temperature dependence of the luminescence emission variables at 1-atm air pressure.

A technique for measuring pressure created by transporting capsules through a liquid pipeline is described. Pressure gradient increases caused by the capsule train is measured in situ. It is computed using the difference of two differential pressure transducers referenced to the total pressure in the pipe flow without capsules. Capsule transport regimes can be identified from said measurements.

An analytic technique uses mean pressure measurements to predict fluctuating loads created by shock-wave turbulent boundary-layer interactions. It assumes that separation shock unsteadiness cause fluctuating loads and that the probability density function of the instantaneous separation shock location is Gaussian. Based on the knowledge of the location of upstream influence and separation, the technique predicts the loads with a 10% accuracy. It relates the measured mean wall pressure, the wall pressure root mean square and the intermittency. Variations of the method are discussed.

The use of a highly elliptical core two-mode fiber for simultaneous measurement of pressure (radial pressure or hydrostatic pressure) and temperature is presented. The sources of errors are discussed. Expressions are developed to calculate the cross sensitivities. From the numerical examples, some useful conclusions are given. Key words: Optical-fiber sensors, simultaneous measurement of pressure and temperature, cross sensitivity.

An experimental investigation of the mixed convection flow and heat transfer inside a divergent heated vertical channel reveals flow reversal for both assisted and opposed convection, and substantial heat transfer in the downstream portions. The channel divergence effect has a decelerating influence on the mainstream and creates instability in the reversed flow. Natural convection dominates the downstream portions and flow reversal takes place at a much lower buoyancy parameter. An adverse pressure gradient pushes the reversed flow upstream and generates vortices.

This paper investigates the transient flow and pressure developments in a piping network due to design parametric and operational variations. Numerical simulations using both the method of characteristics and the finite difference formulation are performed and compared. The transient fluid pressure pulsations in the pipes are examined in both the time and frequency domains using a Fast Fourier Transform (FFT) algorithm. The parametric studies consider changes in i) the main pipe size, ii) the valve closing time at the branch outlet, iii) the piping system configuration (both single and multiple branched systems), and iv) the frequency of pressure pulsation at the branch outlet (manifold effect). The paper discusses the sensitivity of the transient fluid pressure and the excitability of the piping natural frequencies at various locations of the pipes, due to valve closing and manifold effects at the branch outlet. The effects of resonance due to pressure frequency variation at the branch outlet are also studied and general conclusions are drawn from these results.

Two three-dimensional compressible Navier-Stokes solvers accurately predict the low mach-number performance of an untwisted rectangular wing and a subsonic transport wing-fuselage configuration. The computed pressure distributions are almost identical and agree well with the experimental data. The predicted pressure distributions are also extremely close to those predicted by an incompressible Navier-Stokes solver. The three flow solvers predict almost similar boundary profiles and the computational time is case dependent. The compressible solvers employ a finite volume formulation.

The flow field inside a 50 percent eccentric whirling annular seal operating at a Reynolds number of 24,000 and a Taylor number of 6600 has been measured using a three-dimensional laser-Doppler anemometer system. Flush mount pressure and wall shear stress probes have been used to measure the stresses (normal and shear) along the length of the stator. The rotor was mounted eccentrically on the shaft so that the rotor orbit was circular and rotated at the same speed as the shaft (a whirl ratio of 1.0). This paper presents mean pressure, mean wall shear stress magnitude, and mean wall shear stress direction distributions along the length of the seal. Phase-averaged wall pressure and wall shear stress are presented along with phase-averaged mean velocity and turbulence kinetic energy distributions located 0.16c from the stator wall, where c is the seal clearance. The relationships between the velocity, turbulence, wall pressure, and wall shear stress are very complex and do not follow simple bulk flow predictions.

Three-dimensional swept-shock-wave/boundary-layer interactions produce highly fluctuating pressure loads on portions of high-speed aircraft. The regions close to the foot of the fin that generates the swept shock wave experience the highest loads. Low-frequency components dominate the fluctuations that are caused by random motion of the primary attachment line. Motion of the separation shock causes an rms pressure peak which decreases with increasing sweepback of the separation line. The causes of the fluctuations are discussed.

The numerical predictions of forebody, leading-edge extension, inlet lip and duct surface pressures in F/A-18A inlet flow compare well with the flight data. A significant degree of flow unsteadiness exists at the engine face. The inlet flow distortions and total pressure recovery at the engine face are at the upper and lower range of test data. The calculated total pressure contours are within the excursion range of the minimum total pressure indicated by the flight data.

Three-axis force sensors based on the principle of pressure pick-up device are characterized by their manufacturability, simple structure, and small size. Their use, however, has not been explored due to the incomplete force information that they provide. This paper proposes a new six-axis force sensor, composed of two three-axis force sensors and a connector, called a Twin-Head type six-axis force sensor (TH force sensor for short). We first describe the theoretical basis for the operation of TH force sensors and provide the characteristic matrix connecting the load and sensor output vectors. While twenty-one types of TH force sensor are theoretically conceivable, we prove that ten types can result in a characteristic matrix with a full rank. We also consider an optimal design in the sense of mimimum condition number.

In the present study, the authors propose a method to determine the pressure distribution acting on contact surfaces and detail the development of a measuring device. The principle of pressure measurement is based on the scattered reflection of light from the surface after contact. The device developed measures the pressure distribution and displays it in three dimensions. Pressure distributions measured on various contact surfaces are shown.

The pressure sensitive paint (PSP) technique efficiently computes pressure on a 4.7% scale F-15E model during a high-speed wind tunnel test. Measured pressure distributions are consistent with the geometric characteristics of the model. In situ paint calibration determines absolute accuracy and quantitative utility. The test procedure of PSP technique is discussed.

A novel method developed for deep cavities suppresses cavity pressure oscillations. Grazing flow over deep cavities cause acoustic resonances. Two cases for deep cavity, involving the single vortex, fundamental frequency excitation and the double vortex, first odd harmonic excitation, are analyzed. Measurement of mode shapes permits the optimization of control strategy for the two resonant conditions.

The pore water pressure of soil samples taken from the Wildlife site in Imperial Valley, California were used to evaluate the performance of piezometers. Pore pressure transducers were installed at various depths of the soil layer where liquefaction is expected to occur during strong ground motions. Measurements from the Wildlife site reveal that the piezometer response was slow when compared to other field and laboratory piezometer measurements.

A new method of calculating the pressure field in the simulation of two-dimensional, unsteady, incompressible, free surface fluid flow by use of a marker and cell method is presented. A critical feature of the new method is the introduction of a finer mesh of cells in addition to the regular mesh of finite volume cells. The smaller (micro) cells are used only near the free surface, while the regular (macro) cells are used throughout the computational domain. The movement of the free surface is accomplished by the use of massless surface markers, while the discrete representation of the free surface for the purpose of the application of pressure boundary conditions is accomplished by the use of micro cells. In order to exploit the advantages offered by micro cells, a new general equation governing the pressure field is derived. Micro cells also enable the identification and treatment of multiple points on the free surface in a single surface macro cell as well as of points on the free surface that are located in a macro cell that has no empty neighbors. Both of these situations are likely to occur repeatedly in a free surface fluid flow simulation, but neither situation has been explicitly taken into account in previous marker and cell methods. Numerical simulation results obtained both with and without the use of micro cells are compared with each other and with theoretical solutions to demonstrate the capabilities and validity of the new method.

A new partial pressure measurement system for CO2 in seawater pCO2 uses a nondispersive infrared gas analyzer (NDIR) and a membrane tube. The membrane enables gaseous CO2 from the seawater to enter the tube and the NDIR estimates the CO2 concentration. The system allows automatic monitoring of seawater pCO2 variations with uncertainties of plus or minus 5 micro atmosphere.

The advanced MKIIIB-conductivity-temperature-depth profiler is usable for hydrographic measurements. The profiler determines the physical parameters of sea water, temperature, pressure and electrical conductivity. The parameter sensors have bit discontinuities which are difficult to identify by the available dead weight testers. For better efficiency of these instruments, a - 3 degree celsius output is necessary.

For [H.sub.2]O densities > 1.0 g/[cm.sup.3], a determination of the ice melting temperature provides the density information required to calculate the P-T path that the sample in a hydrothermal diamond-anvil cell follows when the sample is heated isochorically. The principal difficulty is the identification of the polymorph because of metastable behavior of ices in the H2O system. Usually, an accurate identification of the liquidus ice phase can be made without analytical instrumentation and requires only careful observations.

The unsteady pressures control the momentum balance for both viscous and nonviscous fluid. The momentum generated in a compressible atmosphere by an impulsive point force is distributed between a moving fluid sphere and a front expanding with the velocity of sound. The net momentum is zero in a transverse section of an incompressible atmosphere. A comparison between the viscous boundary layer and the actuator surface of the atmosphere shows that the power taken by actuator is a fraction of the work performed by the system from outside.