Development of a MEMS microphone array for the measurement of wall pressure fluctuation field

2018 ◽  
Vol 2018.24 (0) ◽  
pp. OS0507
Author(s):  
Akinori ZAKO ◽  
Atsuki MIYAJIMA ◽  
Yoshitugu NAKA
Keyword(s):  
Pressure Fluctuation ◽  
Microphone Array ◽  
Wall Pressure ◽  
Fluctuation Field ◽  
Wall Pressure Fluctuation ◽  
Mems Microphone

Stochastic Estimation of the Flow Structure Downstream of a Separating/Reattaching Flow Using Wall-Pressure Array Measurements

Volume 1 ◽  
2004 ◽  
Author(s):  
Mohamed Daoud ◽  
Ahmed Naguib
Keyword(s):  
Velocity Field ◽  
Pressure Fluctuation ◽  
Microphone Array ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Splitter Plate ◽  
Array Measurements ◽  
Wall Pressure Fluctuation ◽  
Developing Flow ◽  
Taylor Hypothesis

This investigation examines the surface-pressure fluctuations and associated flow structures spatiotemporally in the developing flow downstream of the reattachment point of a fence-with-splitter-plate flow. Simultaneous measurements of the wall-pressure and velocity field were undertaken using a 16-microphone array, extending over the streamwise range 1.67 < x/Xr < 3.33 (where Xr is the mean reattachment length), and X-hotwire sensor at two Reynolds numbers of 8000 and 16000, based on the fence height above the splitter plate. The array data were used to obtain the wavenumber-frequency spectrum of the wall-pressure fluctuation. The results illustrate that Taylor hypothesis of frozen eddies reasonably describes the flow in the investigated zone. This allowed utilization of the time-dependent LSE of the velocity field to estimate the spatial structure of the flow above the microphone array. The results confirm the association of the most-energetic pressure fluctuation with the passage of quasi-periodic vortices.

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.

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