Studies of Nquot;waves and weak shock waves in the 75x100 mm shock tube

In attempts to understand the effect of turbulence on sonic13; boon and the thickening of sonic boom shocks in the atmosphere,transient i;f F* waves and weak shock waves were generated by modifying the driver chamber of the existing 75 x 100 mm NAL shock tube. For generation of the transient 'N' waves existing driver chamber was re-placed by area varying chamber viz. pyramidal wedge or abruptly varying area chamber.. Due to the diaphragm bursting limitations although all the three chambers could13; generate clean and reasonably good transient 'N' waves, strength of the waves could not be reduced to sonic boom. An orifice plate of 0.00125 opening area ratio, placed in the driven chamber, could reduced the strength of the 'N' wave but distorted the N wave considerably.13; To remove the distortions of the 'N wave and to reduce13; the shocks strength further down to sonic boom shocks, weak13; shock waves were generated using combination of large area divergence at the diaphragm and an orifice plate in the driven chamber.Shock waves of various strengths were generated and their rise times were measured. Also to study the effects of turbulence on the wave signature, zero mean flow turbulence was generated in a small section of the driven chamber. The signatures shapes before and after the turbulent chamber were studied It was observed that the turbulent had not noticeably distorted the the traveling signatures. It was also observed that with reduced shock strength, rise times of the shocks had increased;13; but it could not be concluded whether the increased rise times were due to the reduced strength or due to the methods adopted for generation of the shock waves