Determination of the VT-relaxation time of molecules from the compression pulse width of a photoacoustic signal: the effect of gas pressure measurement errors

2016 ◽  
Keyword(s):  
Relaxation Time ◽  
Pressure Measurement ◽  
Measurement Errors ◽  
Pulse Width ◽  
Photoacoustic Signal ◽  
Gas Pressure ◽  
Compression Pulse

scholarly journals Iterative method for determination of the laser beam profile and τV-T

2008 ◽  
Vol 6 (1) ◽  
pp. 71-76
Author(s):  
Mihailo Rabasovic ◽  
Dragan Markushev
Keyword(s):  
Relaxation Time ◽  
Laser Beam ◽  
Photoacoustic Signal ◽  
Linear Process ◽  
Beam Profile ◽  
Photoacoustic Tomography ◽  
Spatial Profile ◽  
Photoacoustic Effect ◽  
Laser Beam Profile

Measuring the vibrational-to-translational relaxation time ?V-T in gases is one of the first applications of the photoacoustic effect. The spatial profile of the laser beam is crucial in these measurements because the multiphoton excitation is investigated. The multiphoton absorption is a non-linear process. Because of this, the top hat profile is preferable. It allows one to deal with nonlinearity in a simple manner. In order to reveal the real laser beam profile, we have slightly changed the theoretical profiles in such a manner that the best matching is obtained between theoretical and experimental photoacoustic signals. Still, there was a question: Is it possible to deduce the laser beam profile directly from the photoacoustic signal, thus avoiding manual changing of the laser beam profile? According to this paper, it is possible. The appropriate method has been found in another photoacoustics application: photoacoustic tomography. Thus, the method for the simultaneous determination of the spatial profile of the laser beam and vibrational-to-translational relaxation time is presented in this paper. It employs pulsed photoacoustics and an algorithm developed for photoacoustic tomography.

Total Pressure Correction of a Sub-Miniature Five-Hole Probe in Areas of Pressure Gradients

2012 ◽  
Author(s):  
J. Town ◽  
A. Akturk ◽  
C. Camcı
Keyword(s):  
Pressure Measurement ◽  
Measurement Errors ◽  
Total Pressure ◽  
Pressure Gradients ◽  
Pressure Data ◽  
Flow Conditions ◽  
Complex Flow ◽  
Ducted Fan ◽  
The Difference ◽  
Best Fit

Five-hole probes, being a dependable and accurate aerodynamic tools, are excellent choices for measuring complex flow fields. However, total pressure gradients can induce measurement errors. The combined effect of the different flow conditions on the ports causes the measured total pressure to be prone to a greater error. This paper proposes a way to correct the total pressure measurement. The correction is based on the difference between the measured total pressure data of a Kiel probe and a sub-miniature prism-type five-hole probe. By comparing them in a ducted fan related flow field, a line of best fit was constructed. The line of best fit is dependent on the slope of the line in a total pressure versus span and difference in total pressure between the probes at the same location. A computer program, performs the comparison and creates the correction equation. The equation is subsequently applied to the five-hole probe total pressure measurement, and the other dependent values are adjusted. The validity of the correction is then tested by placing the Kiel probe and the five-hole probe in ducted fans with a variety of different tip clearances.

scholarly journals Nano silica diaphragm in-fiber cavity for gas pressure measurement

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Shen Liu ◽  
Yiping Wang ◽  
Changrui Liao ◽  
Ying Wang ◽  
Jun He ◽  
...  
Keyword(s):  
Pressure Measurement ◽  
Gas Pressure ◽  
Nano Silica

scholarly journals Determination of Vapor-Liquid Equilibrium from Total Pressure Measurement

1971 ◽  
Vol 14 (4) ◽  
pp. 252-256 ◽  
Author(s):  
Kunio Nagahama ◽  
Seijiro Suda ◽  
Toshikatsu Hakuta ◽  
Mitsuho Hirata
Keyword(s):  
Pressure Measurement ◽  
Total Pressure ◽  
Liquid Equilibrium ◽  
Vapor Liquid Equilibrium ◽  
Vapor Liquid
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