Accession Number : AD0827935

Title :   MOIRE PATTERN TECHNIQUE FOR THE DETECTION OF SHOCKWAVES,

Corporate Author : NAVAL ORDNANCE LAB WHITE OAK MD

Personal Author(s) : Bampfield, James F., Jr

Report Date : 05 JAN 1968

Pagination or Media Count : 25

Abstract : An optical means of detecting and recording the structure of shockwaves formed in air is presented. The system is based upon the use of a special case of moire fringes and approaches the sensitivity usually associated with Schlieren type optical instruments. It has, in addition to a high sensitivity, a ruggedness and ease of use which makes it suitable for field-type applications. The moire pattern technique presented here is, for a specific piece of equipment, theoretically capable of sensing a 0.01% density change in air at atmospheric pressure and corresponds to a pressure differential of the order of 0.003 psi (about 0.2 millibar). Pictures showing a pressure differential of the order of 0.08 psi (5.4 millibars) have been made. No special attempts were made to record smaller pressures. (Author)

Descriptors :   (*SHOCK WAVES, DETECTION), EXPLOSION EFFECTS, OPTICAL PHENOMENA, ATMOSPHERIC REFRACTION, REFRACTIVE INDEX, SCHLIEREN PHOTOGRAPHY, SENSITIVITY, DENSITY.

Subject Categories : Explosions

Distribution Statement : APPROVED FOR PUBLIC RELEASE