PERFORMANCE EVALUATION OF A CAVITY TYPE SILENCER, WITH PERFORATED BRIDGE, USING A COLD FLOW TEST RIG

Abstract

Silencers play an important role in reducing the noise pollution. The performance of a silencer can be evaluated by the transmission loose through it. The cavity type s ,fencer is a class of reactive silencers which are widely used. To evaluate the performance of a caiity type silencer, a cold flow test rig was used. Its performance was compared with the introduction of perforated bridge between the inlet and outlet extensions of the same configuration. The probe tube traverse technique was selected for experimentation. The measurements were made at three frequencies viz 700 Hz, 1400 Hz, 2100 Hz and 4 °it tour flog rates with Mach number as Me 0.00, Mn 0.025, Hw 0.05, Ma' 0.075. The standing wave pattern were plotted Icr both the configurations and were compared. The standipg wave Matte `r were used to estimate the pressure reflection i cierit, energy flux density and subsequently the trti* smission loss of the silencer was estimated. In order to verity the reliability of measurements, the pressure reflection coefficient was compared with the standard published resul ,te. Its deviation was noted from its mean value. Finally, by comparing the transmission lose for the two, configurations, the effectiveness of the perforated bridge element was estimated.