MATHEMATICAL MODELS WITH APPLICATION FOR THE EFFECT OF HYDROGRAPHIC FACTORS ON ACOUSTIC ENERGY TRANSMISSION FROM THE AIR GUN SOURCES

Abstract

The present study, which is confined to investigate the effect of hydrographic parameters on the acoustic pressure wave radiated by the air-gun in the water and the effect of the shock wave introduced by non-explosive air-gun (volume Vc=I/6 Land chamber pressure Pc=l50 atm), reveals that the primary pressure is found to be directly proportional to both the water density and temperature whereas acoustic pressure (at first maximum bubble radius) is found to be inversely proportional to both the water density and temperature. Moreover, the instantaneous primary-to­ bubble ratio increase by 0.008% when the water temperature was increased from 20 °C to 40 °C and the primary pressure and the acoustic pressure (at first maximum radius) are directly proportional to the depth of the water.

The present study indicates that the bubble pulse oscillation period is found to be decreasing by about 1.6% over that period predicted for the smaller value of the specific heat ratio when it increases by 0.01. Through the shock pulse duration- the intensity of the energy radiated near the source is inversely proportional to the bubble radius-square. The energy intensity approachs the conditions of decreasing is proportional to the bubble radius as the velocity of the bubble wall less more than critical.

As for the effect of the energy radiated by an air gun of volume 1/6 L, chamber pressure 150 atm and has an initial energy of 13600 joule on the marine life, it is indicted that if the value ofK (coefficient dependent on fish species) is 54 the maximum dangerous radius is 4.4 m (i.e., the risk of damage to invertebrata is 4.4 m), if the value ofK is 12 the minimum dangerous radius is 1 m (i.e., the risk of damage to vertebrata is 1 m), if the value ofK is 25.5 the middle dangerous radius is 2.1 m (i.e., the risk of damage to protochordata is 2.1 m) and the risk of damage to marine life increases with increasing depth at which the air gun is fired.