Abstract, “The effects of a kinematic field of velocity fluctuations on the loudness metrics of two waveforms are examined with a three-dimensional one-way propagation solver. The waveforms consist of an N-wave and a simulated low-boom from NASA’s X-59 QueSST aircraft. The kinematic turbulence is generated using a von Karman composite spectrum, which is dependent on …
Category Archives: Aeronautics
AEDC von Karman Facility
Variable Density Wind Tunnel
When visiting NASA Langley I had Josh Blake kindly take my picture by the Variable Density Wind Tunnel. Pioneered by Max Munk, leading theoretician in aerodynamics in America in our early years of aviation. National historical landmark: The test section and airflow passages built into the VDT pressure vessel formed a continuous flow of pressurized …
On the Panel Method
After this I got more into aerodynamic research. The area rule involves calculating the flow about a bumpy body of revolution. Existing methods for calculating it were very poor. K. E. Van Every, my boss, talked to me about looking over the available methods and seeing what was best. I did and discovered an entirely …
Dryden, Prandt, von Kármán, and Tsien
Hugoniot
Hugoniot with classmates from the École Polytechnique, 1870 . Hugoniot is second from left, front row, see insert.
Experiments in a Large-Boundary Layer Wind Tunnel: Propagation of Noise through the Turbulent Boundary Layer
My Group recently published a paper on a multiyear experiment campaign. We used the National Science Foundation Boundary Layer Wind Tunnel and sent acoustic waves through the boundary layer. We examined how turbulent structures altered the waveforms. The purpose is to create a high quality database available to the community to understand acoustic-turbulent interactions. Zhang, …
Paul Richard Heinrich Blasius
At Easter 1902 I had sat my final college examination, and was now studying mathematics. This was not simple for me: Although one can see what follows from certain algebraic manipulations, why would this be done? “By mathematics, you are convicted, instead of convinced”, according to the philosopher Schopenhauer. After some time, I realized that, …
The History of the Navier-Stokes Equations
Over the course of a few years I have collected pictures, biographies, and other tidbits about the many famous people who have created, studied, and dedicated their lives to the Navier-Stokes equations. I set it to the music of Carmina Burana of the MIT Choir (Creative Commons). Enjoy!
Sankar’s Helicopter Aerodynamics
I’m really impressed with Professor Sankar’s website on fundamentals of aerodynamics of helicopters. It is often said in the aerospace community that if you understand the aerodynamics of helicopters then you can understand anything. It is really challenging! He has also posted a number of interesting items on aeroacoustics of rotorcraft. I have learned a …