A Method for Suppression of Pressure Pulses in Fluid-Filled Piping—Part I: Theoretical Analysis

1992 ◽  
Vol 114 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Y. W. Shin ◽  
A. H. Wiedermann
Keyword(s):  
Theoretical Analysis ◽  
Pressure Pulse ◽  
Substantial Reduction ◽  
Pulse Height ◽  
Practical Interest ◽  
Nondestructive Method ◽  
Trade Off ◽  
Pressure Pulses ◽  
Fluid Jets ◽  
Pressure Surge

A simple, nondestructive method to suppress pressure pulses in fluid-filled piping is theoretically analyzed, and the result provides the basis needed for design and evaluation of a pressure-pulse suppression device based on the proposed theory. The method is based on forming of fluid jets in the event of a pressure surge, such that the pulse height and the energy of the pulse are reduced. The results for pressure pulses in the range of practical interest show that a substantial reduction in the pulse height can be attained, with accompanying reduction of the pulse remaining in the system. The analysis also reveals that a certain amount of trade-off exists in the design of the suppression device; a certain level of pulse energy remaining in the system must be accepted in order to keep the pulse height below a certain level, and vice versa.

scholarly journals Partial Cavities: Pressure Pulse Distribution Around Cavity Closure

1993 ◽  
Vol 115 (2) ◽  
pp. 249-254 ◽  
Author(s):  
Q. Le ◽  
J. P. Franc ◽  
J. M. Michel
Keyword(s):  
Pressure Pulse ◽  
Pulse Height ◽  
Leading Edge ◽  
Limit Case ◽  
Production Rates ◽  
Partial Cavitation ◽  
Pressure Pulses ◽  
Cavity Closure ◽  
Stable Cavity

Pressure pulse height spectra (PPHS) are measured in the case of partial cavitation attached to the leading edge of a hydrofoil. It is shown that the distributions of pressure pulses around cavity closure may significantly differ according to the type of cavity. In the case of a thin, well-closed and stable cavity, the pressure pulse distributions exhibit a strong maximum centered on the visible cavity termination. As the cavity becomes thicker and increasingly open and unsteady, the pressure pulse distribution widens. In the limit case of a cavity periodically shedding bubble clusters, no definite maximum in the pressure pulse distribution is observed. In addition, scaling of pressure pulse height spectra is approached from measurements at two different velocities. It is shown that the pressure pulse height spectra can be correctly transposed from a velocity to another one from two basic scaling rules concerning pulse heights and production rates of bubbles.

A Method for Suppression of Pressure Pulse in Fluid-Filled Piping—Part II: Experimental Verification

1992 ◽  
Vol 114 (1) ◽  
pp. 66-73
Author(s):  
Y. W. Shin ◽  
E. F. Bielick ◽  
A. H. Wiedermann ◽  
C. E. Ockert
Keyword(s):  
Experimental Verification ◽  
Pressure Pulse ◽  
Practical Importance ◽  
Companion Paper ◽  
Nondestructive Method ◽  
Experimental Setup ◽  
Practical Applications ◽  
Test Models ◽  
Pressure Pulses ◽  
Theoretical Predictions

A simple, nondestructive method to suppress pressure pulses in fluid-filled piping was proposed and theoretically analyzed in the previous companion paper. In this paper, the proposed method is verified experimentally. The results of experiments performed for the range of parameters of practical importance indicated that the attenuation of pressure pulses was sufficiently large for practical applications and in accordance with the theoretical predictions. This paper describes the experimental setup and the test models of the proposed pulse suppression devices and discusses the experimental results. In particular, the measured attenuation factors (transmitted pressure/incident pressure) are presented and compared with the theoretical predictions.

Realization of Optional Method of Determining the Concrete's Freeze-Thaw Resistance with Help of Dilatometer

2014 ◽  
Vol 1082 ◽  
pp. 258-264
Author(s):  
Olga Pertseva ◽  
Sergey Nikolskiy
Keyword(s):  
Theoretical Analysis ◽  
High Efficiency ◽  
Nondestructive Method ◽  
Labor Input ◽  
Laboratory Equipment ◽  
Freeze Thaw

It’s really necessary to determine freeze-thaw resistance of concrete faster and correctly.The offered method is based on measurement of long strength by nondestructive method, based onacoustic issue. Also dilatometer is used. During this research, the theoretical analysis of concrete'sspecimen dependence on freeze-thaw resistance and energy, which is emitted by a specimen duringdestruction, has been carried out. Freeze-thaw resistance of a specimen is calculated as themathematical relation of these energies. Correctness of the offered method is proved byexperiments. The offered method is characterized by small labor input, high efficiency and a wideapplication scope, but special laboratory equipment is needed.

Density Measurement of Thin Sputtered Carbon Films

1988 ◽  
Vol 32 ◽  
pp. 323-330 ◽  
Author(s):  
G. L. Gorman ◽  
M.-M. Chen ◽  
G. Castillo ◽  
R. C. C. Perera
Keyword(s):  
Carbon Film ◽  
Processing Condition ◽  
Density Measurement ◽  
Practical Interest ◽  
Processing Parameters ◽  
Carbon Films ◽  
Nondestructive Method ◽  
Gas Pressure ◽  
X Ray ◽  
Thin Carbon

AbstractThe densities of sputtered thin carbon films have been determined using a novel X-ray technique. This nondestructive method involves the measurement of the transmitivity of a characteristic soft (low energy) X-ray line through the carbon film, and using the established equation I1 = I0eμpt where I1/I0 is the transmitivity, fi the photo absorption cross section, t the independently measured thickness, the density p can be easily solved for. This paper demonstrates the feasibility of using this simple technique to measure densities of carbon films as thin as 300 Å, which is of tremendous practical interest as carbon films on this order of thickness are used extensively as abrasive and corrosive barriers (overcoats) for metallic recording media disks. The dependence of the density upon film thickness for a fixed processing condition is presented, as also its dependence (for a fixed thickness) upon different processing parameters (e.g., sputtering gas pressure and target power). The trends noted in this study indicate that the sputtering gas pressure plays the most important role, changing the film density from 2.4gm/cm3 at 1 mTorr to 1.5gm/cm3 at 30 mTorr for 1000 Å thick films.

Midlatency respiratory-related somatosensory activity and perception of oral pressure pulses in normal humans

2001 ◽  
Vol 90 (6) ◽  
pp. 2048-2056 ◽  
Author(s):  
J. Andrew Daubenspeck ◽  
Harold L. Manning ◽  
John C. Baird
Keyword(s):  
Evoked Potentials ◽  
Pressure Pulse ◽  
Applied Pressure ◽  
Normal Subjects ◽  
Magnitude Production ◽  
Global Field Power ◽  
Oral Pressure ◽  
Pressure Pulses ◽  
Standard Pressure ◽  
The Right

A direct relationship exists within subjects between midlatency features (<100 ms poststimulus) of respiratory-related evoked potentials and the perceived magnitude of applied oral pressure pulse stimuli. We evaluated perception in 18 normal subjects using cross-modality matching of applied pressure pulses via grip force and estimated mechanoafferent activity in these subjects by computing the global field power (GFP) from respiratory-related evoked potentials recorded over the right side of the scalp. We compared across subjects 1) the predicted magnitude production for a standard pressure pulse and 2) the slope (β) and 3) the intercept (INT) of the Stevens power law to the summed GFP over 20–100 ms poststimulus. Both the magnitude production for a standard pressure pulse and the β showed an inverse relationship with the summed GFP over 20–100 ms poststimulus, although there was no relationship between INT and the summed GFP. This may partially reflect characteristics of the mechanosensors and surely includes aspects of cognitive judgment, because we found and corrected for a high correlation between, respectively, β (and INT) for pressure pulses and β (and INT) for estimation of line lengths, a nonrespiratory modality. The relatively shallow, even inverse GFP-to-perception relationship suggests that, despite marked differences in the magnitude of afferent traffic, normal subjects seem to perceive things similarly.

Response of Water-Filled Thin-Walled Pipes to Pressure Pulses: Experiments and Analysis

1980 ◽  
Vol 102 (1) ◽  
pp. 56-61 ◽  
Author(s):  
C. M. Romander ◽  
L. E. Schwer ◽  
D. J. Cagliostro
Keyword(s):  
Pressure Pulse ◽  
Fluid Structure Interaction ◽  
Two Dimensional ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Modeling Techniques ◽  
Pressure Pulses ◽  
Piping Systems ◽  
Dimensional Finite Element ◽  
Thin Walled

Experiments are performed to verify modeling techniques used in fluid-structure interaction codes that predict the response of liquid-filled piping systems to strong pressure pulses. Pressure pulses having a 150-μs rise time, a 2000-psi (13.8 MPa) magnitude, and a 3-ms duration are propagated into straight, water-filled Ni 200 pipes (3-in. (7.6-cm) O.D. 0.065-in. (0.165-cm) wall). Attenuation of the pressure pulse and the strain and deformation along the pipes are measured. The experiments are modeled in WHAM, a two-dimensional, finite-element, compressible fluid-structure interaction code. The experimental and analytical results are discussed in detail and are found to compare favorably.

On the Phenomenon of Pressure Pulses Reflecting Between Blades of Adjacent Blade Rows of Turbomachines

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Jerzy A. Owczarek
Keyword(s):  
Pressure Pulse ◽  
Physical Phenomenon ◽  
Research Work ◽  
Axial Compressor ◽  
Rotor Blades ◽  
Test Results ◽  
Lehigh University ◽  
Pressure Pulses ◽  
Excitation Frequencies ◽  
Asme Paper

The recently revived interest in “acoustic resonances,” whose details are still not well defined or understood, points to a realization that a new look at some previously unrecognized findings is needed to explain problems encountered in operation of compressors and turbines. The purpose of this paper is to call the attention of the turbomachinery community to an important physical phenomenon of pressure waves in form of pulses, which reflect between blades of adjacent blade rows of turbomachines discovered more than 40 years ago, about whose existence and consequences there is little awareness today. The turbine test results which led the author in 1957 to hypothesize the existence of the phenomenon of reflecting pressure pulses are described. Subsequently, his 1966 ASME paper is discussed. In it, the author reported on the photographed observations of pressure pulses reflecting between stationary nozzles and moving blades of a water-table turbine at Lehigh University, on the description of the various types of such waves, and on an explanation of some of the resonant blade excitation frequencies observed by National Advisory Committee for Aeronautics (NACA) in a turbine of turbojet engine. This is followed by a description of his 1984 ASME paper, in which more general formulae were derived for the blade excitation frequencies caused by the reflections of pressure pulses between the rotor blades, and both upstream and downstream stator vanes. These equations were subsequently used to explain the blade excitation frequencies measured in an axial compressor stage. Finally, his 1992 AIAA paper is discussed, in which additional formulae relating to the reflecting pressure pulses were derived, and the process of formation of a pressure pulse was explained. To put this work in perspective, the author provided, in mostly chronological order, excerpts from reports on operational problems encountered with turbomachines in service and brief descriptions, from selected publications, of pertinent research work.

scholarly journals Detection of Onset, Systolic Peak and Dicrotic Notch in Arterial Blood Pressure Pulses

2017 ◽  
Vol 50 (7-8) ◽  
pp. 170-176 ◽  
Author(s):  
Omkar Singh ◽  
Ramesh Kumar Sunkaria
Keyword(s):  
Blood Pressure ◽  
Wavelet Transform ◽  
Arterial Blood Pressure ◽  
Pressure Pulse ◽  
Data Set ◽  
Dicrotic Notch ◽  
Arterial Blood ◽  
Comparison Results ◽  
Empirical Wavelet Transform ◽  
Pressure Pulses

In this paper, we proposed an effective method for detecting fiducial points in arterial blood pressure pulses. An arterial blood pressure pulse normally consists of onset, systolic peak and dicrotic notch. Detection of fiducial points in blood pressure pulses is a critical task and has many potential applications. The proposed method employs empirical wavelet transform for locating the systolic peak and onset of blood pressure pulse. The proposed method first estimates the fundamental frequency of blood pressure pulse using empirical wavelet transform and utilizes the combination of the blood pressure pulse and the estimated frequency for locating onset and systolic peak. For dicrotic notch detection, it utilizes the first-order difference of blood pressure pulse. The algorithm was validated on various open-source databases and was tested on a data set containing 12,230 beats. Two benchmark parameters such as sensitivity and positive predictivity were used for the performance evaluation. The comparison results for accuracy of the detection of systolic peak, onset and dicrotic notch are reported. The proposed method attained a sensitivity and positive predictivity of 99.95% and 99.97%, respectively, for systolic peaks. For onsets, it attained a sensitivity and predictivity of 99.88% and 99.92%, respectively. For dicrotic notches, a sensitivity and positive predictivity of 98.98% and 98.81% were achieved, respectively.

Model of back pressure pulses generated by coupled pressure pulse (CPP) technology

2014 ◽  
Vol 68 ◽  
pp. 175-184 ◽  
Author(s):  
Urs Rhyner ◽  
Robert Mai ◽  
Hans Leibold ◽  
Serge M.A. Biollaz
Keyword(s):  
Pressure Pulse ◽  
Back Pressure ◽  
Pressure Pulses
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