Correlation Characteristics of a Wall Pressure Fluctuation Field in a Turbulent Boundary Layer Induced by a Longitudinal Flow along a Flexible Extended Cylinder

Voskoboinick, V. A.; Гринченко, В. Т.; Makarenkov, A. P.

doi:10.1615/interjfluidmechres.v30.i6.70

Cited by 9 publications

(3 citation statements)

References 16 publications

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“…5b). The group velocity of the transfer of vortex structures was determined from the dependence cg max U = /  , where and max  is the delay time for which the maximum of the cross-correlation was observed [6,8].…”

Section: Research Resultsmentioning

confidence: 99%

Transversely Streamlined Cylinder on Rigid Surface

Voskoboinick

Voskoboinyk

Onishchenko

et al. 2021

JNAM

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The results of experimental studies are presented in order to study the features of the formation of separated and vortex flows in the vicinity of a transversely streamlined cylinder on the surface of a hydraulically smooth rigid surface and to determine the space-time characteristics of sources of wall pressure fluctuations. The studies were carried out in laboratory conditions on transversely streamlined cylinders, which were located on a rigid surface. The field of wall pressure fluctuations was measured by a group of miniature piezoceramic pressure fluctuation sensors, which were installed flush with the streamlined rigid surface in front of the cylinder and in its wake. The research results were processed and analyzed using the mathematical apparatus of the theory of probability and mathematical statistics. The spectral and correlation characteristics of the separated flow in the vicinity of a transversely streamlined cylinder are obtained.

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Section: Research Resultsmentioning

confidence: 99%

Transversely Streamlined Cylinder on Rigid Surface

Voskoboinick

Voskoboinyk

Onishchenko

et al. 2021

JNAM

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“…Delay time of the correlation signal and it sign with a fixed distance between the velocity fluctuation sensors allows to obtain the transfer velocity and the direction of motion of coherent vortex structures or sources of correlated velocity fluctuations (Vinogradnyi et al 1989, Voskoboinick et al 2003, Voskoboinick 2008. For these conditions, the maximum of the cross-correlation coefficient of velocity fluctuations was registered for the delay time of approximately 0.07 s and the cross-correlation coefficient was 0.92, which was observed between 4 and 5 seconds in figure 10.…”

Section: Measurement Resultsmentioning

confidence: 99%

Feature of the vortex and the jet flows around and inside the three-row pile group

Voskobijnyk¹,

Voskoboinick²,

Voskoboinyk³

et al. 2016

Scour and Erosion

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In this article the results of experimental research of kinematics and the dynamics of horseshoe vortex structures, wake vortices and lateral jet flows, formed around and inside the pile group of three-row grillage, set on a flat rigid surface and sand soil, are presented. Visualization of flow is conducted using water soluble coatings and contrast substances, introduced into the stream. The fields of velocity, pressure and shear stresses around and inside the pile construction were investigated using the miniature sensors of the velocity, dynamic pressure and pressure fluctuations. The place of formation and features of development of large-scale horseshoe vortex structures and wake vortices, and the hydrodynamic characteristics of the vortex and jet flow were determined. The space-time correlation and spectral characteristics of the velocity and pressure fluctuations were measured. The scale of the coherent vortex structures, their frequencies of rotations and oscillations, convective velocities and direction of transfer were determined. The three-dimensional spectrograms and correlograms of vortex and the jet flow about and inside the three-row pile grillage were obtained.

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“…As a result, intense vortex and jet structures are separated from the valve leaflets, and the flow becomes unsteady and unstable with a high degree of turbulence. It is known that turbulent flows generate intense hydrodynamic noise, which has a sound and pseudo-sound nature [42][43][44]. Sound fluctuations of the velocity and pressure are associated with the compressibility of the medium, propagate into the environment with the sound velocity, which is determined by the elasticity of the medium, and obey the principle of superposition.…”

Section: Methodsmentioning

confidence: 99%

Statistical Characteristics of Flow Field through Open and Semi-Closed Bileaflet Mechanical Heart Valve

et al. 2020

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The formation of thrombi on the streamlined surface of the bileaflet mechanical heart valves is one of the main disadvantages of such valves. Thrombi block the valve leaflets and disrupt the cardiovascular system. Diagnosis of thrombosis of the bileaflet mechanical heart valves is relevant and requires the creation of effective diagnostic tools. Hydroacoustic registration of the heart noise is one of the methods for diagnosing the operation of a mechanical heart valve. The purpose of the research is to determine the statistical characteristics of the vortex and jet flow through the open and semi-closed bileaflet mechanical heart valve, to identify hydroacoustic differences and diagnostic signs to determine the operating conditions of the valve. Experimental studies were conducted in laboratory conditions on a model of the left atrium and left ventricle of the heart between which there was the bileaflet mechanical heart valve. Hydrodynamic noise was recorded by miniature pressure sensors, which were located downstream of the valve. The vortex and jet flow behind the prosthetic heart valve were non-linear, random processes and were analyzed using the methods of mathematical statistics and probability theory. The integral and spectral characteristics of the pressure field were obtained and the differences in the noise levels and their spectral components near the central and side jets for the open and semi-closed mitral valve were established. It was shown that hydroacoustic measurements could be an effective basis for developing diagnostic equipment for monitoring the bileaflet mechanical heart valve operation. Doi: 10.28991/SciMedJ-2020-0204-1 Full Text: PDF

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Correlation Characteristics of a Wall Pressure Fluctuation Field in a Turbulent Boundary Layer Induced by a Longitudinal Flow along a Flexible Extended Cylinder

Cited by 9 publications

References 16 publications

Transversely Streamlined Cylinder on Rigid Surface

Transversely Streamlined Cylinder on Rigid Surface

Feature of the vortex and the jet flows around and inside the three-row pile group

Statistical Characteristics of Flow Field through Open and Semi-Closed Bileaflet Mechanical Heart Valve

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