Measurement of the density field around an airgun muzzle by pulsed TV holography

• The density distribution in the air surrounding an airgun muzzle is visualized using pulsed TV holography. A ruby laser emitting short coherent light pulses (30 ns) is used as light source. Pulsed holograms are captured by a CCD-camera and their optical phase difference is evaluated by means of the Fourier transform method. A number of experiments are performed where the event is recorded at different instants of time as the lead bullet is about to leave the muzzle. Phase maps showing the integrated density distribution are presented. A jet with decreasing density ahead of the bullet can be observed. At the moment the bullet leaves the muzzle, a spherical sound pressure wave starts to propagate out into the air. The density in the jet in front of the traveling bullet can be calculated by means of full shock-wave theory. The theory confirms the decrease in density observed in the measurements

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Teknisk mekanik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Applied Mechanics (hsv//eng)

Nyckelord

Experimentell mekanik

Experimental Mechanics

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