“Shock Diamonds” in the afterburner of a NASA SR-71B Jet * * * Sound pressure levels are limited by the physical characteristics of the surrounding medium. The ambient air pressure at sea level is “one atmosphere,” or approximately 14.7 psi on the absolute scale. The… Read more
The Matlab scripts in SPL.zip calculate the one-third sound pressure level for an acoustic pressure time history. SPL.m is the main script. The remaining scripts are supporting functions. The scripts have options for A, B & C-weighting. See also: Matlab Acoustic Page * * *… Read more
I am working on a commerical aircraft project for which the external fluctuating pressure along the fuselage must be predicted for cruise. I have done a preliminary literature survey. I have loosely assembled some reference data and notes in a paper: Jet Aircraft Fuselage External… Read more
Preliminary notes for acoustic waves: c = speed of sound f = frequency k = wavenumber lambda = wavelength r = radius wavelength is equal to the speed of sound divided by frequency lambda = c / f wavenumber is equal to two pi divided… Read more
Clintonville, Wisconsin is an inland community, adjacent to Lake Pigeon. USA Today reported on March 21, 2012 that a series of mysterious booms have been fraying residents’ nerves. City administrator Lisa Kuss said the booms have roused people from their beds and into the streets… Read more
I posted a newsletter at: http://www.vibrationdata.com/Newsletters/March2012_NL.pdf The topics are: James Webb Space Telescope Isolation The Prandtl-Glauert Singularity Seneca Guns Loudest Stadium Crowd Please also see my profile at: http://www.nasa.gov/offices/nesc/academy/Tom_Irvine_bio.html Tom Irvine
I have posted the January 2012 Newsletter at: http://www.vibrationdata.com/newsletters.htm The topics are: Slow Earthquakes Rumbler Siren Shepard Tones Toadfish Mating Call There are seven accompanying sound files and one Matlab script. Please let me know if you have any questions. Thank you, Tom Irvine
Here is an excerpt from a National Transportation Safety Board Aircraft Accident Report… Research has shown that fundamental frequency (pitch) can convey information about a speaker’s psychological stress. With regard to fundamental frequency, the Safety Board used the following guidelines from two previous accident investigations… Read more
I have posted a Vibrationdata Newsletter with an aviation theme at: http://www.vibrationdata.com/Newsletters/August2011_NL.pdf The articles include discussions of . . . 1. The XF-84H turboprop aircraft which had supersonic blade tip velocity 2. Aircraft landing shock 3. Turbofan engine buzz-saw noise Military Aircraft Carrier & Normal… Read more
Here is a survey question. NASA-HDBK-7005(2001) gives the Franken method as a semi-empirical method for predicting the vibration response of a cylindrical skin to an acoustic pressure field, via extrapolation. Franken originally published this method in 1962 based on rocket engine static test fire data.… Read more