Numerical study on supersonic internal cavity flows - What causes the pressure fluctuations?

1999 ◽  
Author(s):  
Yoko Takakura ◽  
Takayoshi Suzuki ◽  
Fumio Higashino ◽  
Masahiro Yoshida
Keyword(s):  
Numerical Study ◽  
Pressure Fluctuations ◽  
Internal Cavity ◽  
Cavity Flows

scholarly journals Numerical study of the vortex breakdown and vortex reconnection in the flow path of high-pressure water turbine

2021 ◽  
Vol 2088 (1) ◽  
pp. 012040
Author(s):  
A V Sentyabov ◽  
D V Platonov ◽  
A V Minakov ◽  
A S Lobasov
Keyword(s):  
Vortex Core ◽  
Vortex Breakdown ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Hydraulic Turbine ◽  
Sliding Mesh ◽  
Precessing Vortex Core ◽  
Vortex Reconnection ◽  
Water Turbine ◽  
Pressure Water

Abstract The paper presents a study of the instability of the precessing vortex core in the model of the draft tube of a hydraulic turbine. The study was carried out using numerical modeling using various approaches: URANS, RSM, LES. The best agreement with the experimental data was shown by the RSM and LES methods with the modelling of the runner rotation by the sliding mesh method. In the regime under consideration, the precessing vortex rope is subject to instability, which leads to reconnection of its turns and the formation of an isolated vortex ring. Reconnection of the vortex core leads to aperiodic and intense pressure fluctuations recorded on the diffuser wall.

scholarly journals Numerical study of pressure and velocity fluctuations in nearly isotropic turbulence

1978 ◽  
Vol 88 (4) ◽  
pp. 685-709 ◽  
Author(s):  
U. Schumann ◽  
G. S. Patterson
Keyword(s):  
Isotropic Turbulence ◽  
Initial Conditions ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Reynolds Numbers ◽  
Companion Paper ◽  
Real Space ◽  
Pressure Gradients ◽  
Velocity Statistics ◽  
Decaying Turbulence

The spectral method of Orszag & Patterson has been extended to calculate the static pressure fluctuations in incompressible homogeneous decaying turbulence at Reynolds numbers Reλ [lsim ] 35. In real space 323 points are treated. Several cases starting from different isotropic initial conditions have been studied. Some departure from isotropy exists owing to the small number of modes at small wavenumbers. Root-mean-square pressure fluctuations, pressure gradients and integral length scales have been evaluated. The results agree rather well with predictions based on velocity statistics and on the assumption of normality. The normality assumption has been tested extensively for the simulated fields and found to be approximately valid as far as fourth-order velocity correlations are concerned. In addition, a model for the dissipation tensor has been proposed. The application of the present method to the study of the return of axisymmetric turbulence to isotropy is described in the companion paper.

A Parametric Study of Incompressible Axisymmetric Internal Cavity Flows

2007 ◽  
Author(s):  
Jeremy Smith ◽  
Lee Wendell ◽  
Abraham Meganathan ◽  
Ahmad Vakili
Keyword(s):  
Parametric Study ◽  
Internal Cavity ◽  
Cavity Flows

Application of Numerical and Experimental Techniques for the Aero-Acoustic Characterisation of a Car Rear-View Mirror

2005 ◽  
Vol 4 (1-2) ◽  
pp. 185-212 ◽  
Author(s):  
Christoph Reichl ◽  
Christian Krenn ◽  
Martin Mann ◽  
Hermann Lang
Keyword(s):  
Acoustic Pressure ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Acoustic Analogy ◽  
Acoustic Characteristics ◽  
Rear View Mirror ◽  
Piv Method ◽  
Local Areas ◽  
Experimental Approaches

Numerical as well as experimental approaches are used to capture aero-acoustic characteristics of a car rear-view mirror. The numerical study splits up into several parts. Using an actual production mirror, particular emphasis must be put on the geometry preparation and mesh generation. Initially, a CFD simulation of the entire car aerodynamics is performed to extract the proper flow boundary conditions for the aero-acoustic simulation of a smaller section surrounding the mirror. Pressure fluctuations on the surfaces extracted during an LES generate the data base required for the aeroacoustic post-processing. The acoustic pressure at several monitoring points is then calculated using Lighthill's Acoustic Analogy. To include refraction effects of the nearby surfaces a direct BEM approach is also employed. Utilizing the PIV method, local areas of increased turbulence are identified experimentally. Microphone measurements with and without the exterior mirror are performed.

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

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