- Develop an experiment device for
generating a signal in tubing systems
- Record pressure signals at given
frequencies through long and short
tubes generated by the device
- Calculate the amplitude ratio and
phase lag between pressure signals of
short and long tubes with respect to
frequency range of interest
- Compare with theoretical predictions
for their validation
signal
- Run speaker from 30-300 Hertz by steps of
2 Hertz
- Speaker frequency response 27-500Hz
- Scan at each frequency for 30 seconds at a
sampling rate of 625 Hz
- Nyquist frequency: max frequency should
be at most half the sampling rate
- Pressure scanner automated with LabVIEW
software
Research Plan
Cross section of
speaker box
- James Ratino designed pressure generator;
speaker in box
- Creates pressure fluctuations in the air
- Based on design by Kirby Herbert for James
Gregg’s Thesis: Development and application of
methods for Evaluation of hurricane shelters
- Connect to computer to generate sinusoidal
waves
Experimental Procedure
Kicker.com
Dynamic Pressure Calibration of
a Tubing SystemLuke [email protected]
Aerospace Engineering
Science, Discovery, and the Universe
Division 731
- Large external wind loads can cause
structures to fail
- Forces are due to large pressure gradients
that occur due to structures’ aerodynamics
nasa.gov http://www.floridahurricaneclaim.org/
- Model used to collect data inside of a wind
tunnel to better understand bluff body flow
- Dynamic pressure measured with pressure
transducer
- Transducer placed inside model measures
pressure across model’s surface
Wind
Model
Transducer
Background
The Problem
- When measuring the pressure with the
transducer we must use long tubes to
connect to the models surface
- The long tubes create distortion in the
signal
Photo Cr. L. Amatucci Photo Cr. L. Amatucci
Photo Cr. L. AmatucciScanivalve.com
Photo Cr. L. Amatucci
- Using LabView program to collect data
and Matlab to analyze data
- Fast Fourier Transform(FFT)
- Converts signal from time domain to
frequency domain
Data Analysis
Results
- Comparing our theoretical ratio
between the short and the long tube to
the recorded ratio we see the trend is
spot on
- These results validate the theoretical
predictions and shows they are true to
our experiments
Acknowledgements: Dr. DongHun Yeo, Matthew Kovarek, James Ratino, Dr. Marc Levitan, Chongqing Fan, Ryan Pemberton and Drew Tkac- Scanivalve, Dr. Eric Lemmon – REFPROP (NIST Boulder)
Photographer: Levick, Edwin
My time at NIST gave me incredible experience in
working in a lab and engineering environment
where my input was very important