Béla Karlovitz was a Hungarian physicist who pioneered research into the generation of electricity directly from a body of hot moving gas without any mechanical moving parts. This process is known as magnetohydrodynamic generation or MHD generation for short. He is also known for Karlovitz number.
In the mid-1930s, while in his native Hungary, Béla Karlovitz approached Siemens in Germany with a request to develop an MHD generator using combustion gases. Siemens referred him to Westinghouse in the USA. He arrived at the Westinghouse research facility in Pittsburgh, Pennsylvania with colleague Denes Halasz in 1938. 
His work there resulted in the world's first patent for the MHD power process on August 13, 1940 (U.S. Patent No. 2,210,918, "Process for the Conversion of Energy").
He worked at Westinghouse until 1947 
The Second World War interrupted development and a practical working device was not built until 1992 by others.
Belá Karlovitz received his M.E. degree from Technical University, Budapest, Hungary and his E.E. degree from the Federal Institute of Technology, Zurich, Switzerland. Besides his publications in MHD, he is the author of publications on turbulent flames, combustion instabilities. He was the Head of the Flame Research Section, Explosives and Physical Science Division, Bureau of Mines, Pittsburgh, PA in 1953. Subsequently, he was with Combustion and Explosive Research, Inc. in Pittsburgh, PA.
In combustion, Karlovitz is known as the first to introduce the concept of flame stretch. The Karlovitz number is named after him. It is a non-dimensional quantity defined as: where is the characteristic flow time (s) and is the flame stretch rate (1/s): ; where is the unit area of the flame and consists of the points that stay on the flame surface.
- Magnetohydrodynamic electrical power generation, Hugo K. Messerle, page 7, J. Wiley, 1995
- Physics in technology, Volume 10, page 219 Institute of Physics (Great Britain), American Institute of Physics
- United States Patent Office patent Patent number: 2210918 Filing date: Aug 12, 1936, Issue date: Aug 1940
- Electronics, Volume 35, McGraw-Hill Pub. Co., 1962, page 27