Wall pressure-fluctuation spectra at small backward-facing steps

2000 ◽  
Author(s):  
B. Efimtsov ◽  
N. Kozlov ◽  
S. Kravchenko ◽  
A. Andersson
Keyword(s):  
Pressure Fluctuation ◽  
Wall Pressure ◽  
Wall Pressure Fluctuation

Intrinsic Mode Entropy Analysis of Tube-Wall Pressure Fluctuation Signals in the Kenics Static Mixer

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Hui-Bo Meng ◽  
Zhi-Qiang Liu ◽  
Yan-Fang Yu ◽  
Qiang Xiong ◽  
Jian-Hua Wu
Keyword(s):  
Pressure Fluctuation ◽  
Tube Wall ◽  
Sample Entropy ◽  
Wall Pressure ◽  
High Frequency Component ◽  
Static Mixer ◽  
Flow Rates ◽  
Multi Scale ◽  
Wall Pressure Fluctuation ◽  
Macro Scale

The multi-scale nonlinear hydrodynamics in Kenics Static Mixer (KSM) with 100 mm in diameter and 2 in aspect ratio was investigated in this work. The time series of tube-wall pressure fluctuation signals were measured at different flow rates ranged of 100~600 L•h-1 and at different axial positions in the range of 420~580 mm away from the cross-section of mixer inlet. It is difficult for composite signals to make an effective analysis by Sample Entropy (SampEn) based on a single scale. The complexity of tube-wall pressure fluctuation signals in a Kenics static mixer was investigated using Intrinsic Mode Entropy (IMEn) based on Sample Entropy algorithm and Empirical Mode Decomposition (EMD) method. Data sampling length and tolerance are optimized based on intrinsic mode entropy. Results of multi-scale analysis of pressure fluctuations indicated that the Sample entropy reaches maximum in the first scale and progressively decreases according to increase of the decomposed order. It is clear that the movement of high frequency component of the pressure signal is the most complicated and is rich in randomness. With the decomposition scales increasing, the complexity of signal decreases and approaches periodic motion eventually. The intrinsic mode entropy of the tube wall pressure signals in KSM has similar development tendencies in different flow rates. Besides, as the flow rates increased, the macro-scale vortexes play a more and more important role and guide the system to develop toward the stable state.

Hydrodynamic and Hydroacoustic Phenomena in the Propeller Wake-Rudder Interaction

2014 ◽  
Author(s):  
Mario Felli ◽  
Silvano Grizzi ◽  
Massimo Falchi
Keyword(s):  
Pressure Fluctuation ◽  
Holistic Approach ◽  
Wall Pressure ◽  
Marine Propeller ◽  
Flow Measurements ◽  
Time Resolved ◽  
Propeller Wake ◽  
Wall Pressure Fluctuation ◽  
Free Running

The present paper describes the major mechanisms underlying the hydroacoustic and hydrodynamic perturbations in a rudder operating in the wake of a free running marine propeller. The study was based on a holistic approach which concerned time resolved visualizations and detailed flow measurements around the rudder as well as wall-pressure fluctuation measurements over the rudder surface, at different deflection angles.

Modeling of wall‐pressure fluctuation based on time‐mean flow field

2002 ◽  
Vol 112 (5) ◽  
pp. 2218-2218
Author(s):  
Yu‐Tai Lee ◽  
William Blake ◽  
Theodore Farabee ◽  
Michael Tse ◽  
Joseph Brown
Keyword(s):  
Flow Field ◽  
Pressure Fluctuation ◽  
Wall Pressure ◽  
Mean Flow ◽  
Wall Pressure Fluctuation
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