scholarly journals Autocorrelation function for estimating static pressure fluctuation intensity in incompressible homogeneous turbulence under an intermediate Reynolds number

2021 ◽  
Vol 1978 (1) ◽  
pp. 012002
Author(s):  
Hiroki Suzuki ◽  
Shinsuke Mochizuki ◽  
Yutaka Hasegawa
Keyword(s):  
Reynolds Number ◽  
Autocorrelation Function ◽  
Pressure Fluctuation ◽  
Static Pressure ◽  
Homogeneous Turbulence ◽  
Fluctuation Intensity

scholarly journals Phase Distribution in the Tip Clearance of a Multiphase Pump at Multiple Operating Points and Its Effect on the Pressure Fluctuation Intensity

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 556
Author(s):  
Guangtai Shi ◽  
Zongku Liu ◽  
Xiaobing Liu ◽  
Yexiang Xiao ◽  
Xuelin Tang
Keyword(s):  
Phase Velocity ◽  
Pressure Fluctuation ◽  
Phase Distribution ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Two Phase ◽  
Multiphase Pump ◽  
Fluctuation Intensity ◽  
Operating Points ◽  
Multiple Operating Points

Tip clearance has a great effect on the flow and pressure fluctuation characteristics in a multiphase pump, especially at multiple operating points. The phase distribution and pressure fluctuation in tip clearance in a multiphase pump are revealed using the CFD (computational fluid dynamics) technology and high-speed photography methods. In this paper, the phase distribution, the gas-liquid two-phase velocity slip, and the pressure fluctuation intensity are comprehensively analyzed. Results show with the increase of the tip clearance, the multiphase pump pressurization performance is obviously deteriorated. In the meantime, the gas accumulation mainly occurs at the hub, the blade suction side (SS), and the tip clearance, and the maximum gas-liquid two-phase velocity difference is near the impeller streamwise of 0.4. In addition, the tip clearance improves the gas-liquid two-phase distribution in the pump, that is, the larger the tip clearance is, the more uniform the gas-liquid distribution becomes. Furthermore, the gas leads to the maximum pressure fluctuation intensity in the tip clearance which is closer to the tip leakage flow (TLF) outlet, and has a greater effect on the degree of flow separation in the tip clearance.

Large-Eddy Simulation and Passive Control of Flows for a Low Pressure Turbine Cascade

2009 ◽  
Author(s):  
Jibing Lan ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Jing Shu
Keyword(s):  
Pressure Fluctuation ◽  
Passive Control ◽  
Static Pressure ◽  
Separation Bubble ◽  
Suction Surface ◽  
Surface Separation ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Fluctuation Frequency

A rectangular bar which just likes a forward-backward facing step was designed to passive control of the Low-Pressure Turbine (LPT) PakB cascade suction surface separation. Large-eddy simulation (LES) was adopted to analyze the separated-transition flows for the PakB cascade with and without the rectangular bar at Re (Reynolds number based on inlet condition and axial chord) of 86,000 and the freestream turbulence intensity of 1%. Computed results of uncontrolled condition agree well with the experimental data of Lake et al.[6, 7]. And the LES results shown that the rectangular bar control device was successful to control the LPT cascade suction surface separation and provides about 10% kinetic loss coefficient reduction from the uncontrolled one. Unsteady flow structures were also investigated in detail. Static pressure fluctuation frequency at six locations, ranging from 0.56Cx to 0.95Cx axial chord location and with a constant wall normal distance y/h = 1.0, was the same to the separation bubble vortex shedding frequency. Unsteady fluctuation velocity was examined too, which confirmed that the separation bubble vortex frequency was the same to the suction surface static pressure fluctuation frequency.

scholarly journals VIBRATION OF PSEUDO-SHOCK IN STRAIGHT DUCT : 2ND REPORT, CALCULATION OF STATIC PRESSURE FLUCTUATION

1984 ◽  
Vol 27 (229) ◽  
pp. 1393-1398 ◽  
Author(s):  
Ryuichiro YAMANE ◽  
Mamoru TAKAHASHI ◽  
Hiroshi SAITO
Keyword(s):  
Pressure Fluctuation ◽  
Static Pressure ◽  
Straight Duct

Pressure fluctuation in high-Reynolds-number turbulent boundary layer: results from experiments and DNS

2012 ◽  
Vol 13 ◽  
pp. N50 ◽  
Author(s):  
Yoshiyuki Tsuji ◽  
Shintaro Imayama ◽  
Philipp Schlatter ◽  
P. Henrik Alfredsson ◽  
Arne V. Johansson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Pressure Fluctuation ◽  
High Reynolds Number ◽  
High Reynolds

scholarly journals STUDY OF THE BEHAVIOURS OF SINGLE-PHASE TURBULENT FLOW AT LOW TO MODERATE REYNOLDS NUMBERS THROUGH A VERTICAL PIPE. PART I: 2D COUNTERS ANALYSIS

2020 ◽  
pp. 108-122
Author(s):  
Akeel M. Ali Morad ◽  
Rafi M. Qasim ◽  
Amjed Ahmed Ali
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Single Phase ◽  
Static Pressure ◽  
Fluid Velocity ◽  
Mixing Length ◽  
Shearing Force ◽  
Vertical Pipe ◽  
Moderate Reynolds Number

This study presents a model to investigate the behavior of the single-phase turbulent flow at low to moderate Reynolds number of water through the vertical pipe through (2D) contour analysis. The model constructed based on governing equations of an incompressible Reynolds Average Navier-Stokes (RANS) model with (k-ε) method to observe the parametric determinations such as velocity profile, static pressure profile, turbulent kinetic energy consumption, and turbulence shear wall flows. The water is used with three velocities values obtained of (0.087, 0.105, and 0.123 m/s) to represent turbulent flow under low to moderate Reynolds number of the pipe geometry of (1 m) length with a (50.8 mm) inner diameter. The water motion behavior inside the pipe shows by using [COMSOL Multiphysics 5.4 and FLUENT 16.1] Software. It is concluded that the single-phase laminar flow of a low velocity, but obtained a higher shearing force; while the turbulent flow of higher fluid velocity but obtained the rate of dissipation of shearing force is lower than that for laminar flow. The entrance mixing length is affected directly with pattern of fluid flow. At any increasing in fluid velocity, the entrance mixing length is increase too, due to of fluid kinetic viscosity changes. The results presented the trends of parametric determinations variation through the (2D) counters analysis of the numerical model. When fluid velocity increased, the shearing force affected directly on the layer near-wall pipe. This leads to static pressure decreases with an increase in fluid velocities. While the momentum changed could be played interaction rules between the fluid layers near the wall pipe with inner pipe wall. Finally, the agreement between present results with the previous study of [1] is satisfied with the trend

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