Figure 2. The test objects, (a) a single diaphragm orifice with a concentric hole with t/do=0.17 and do/di=0.63, (b) double orificest/do=0.17, di/do=0.63, L=3do (c)ovalshape resonator, (d) complex side branch resonator(e)two side-branches in series (compact resonator)

From

Experimental Assessment of Noise Generation from I.C. Engine Intake and Exhaust Systems Components

Sabry Allam

American Journal of Vehicle Design. 2015, 3(1), 6-15