Bbc Brown, Boveri & Company, Limited

Tony Kollbrunner

Fritz W Spinnler

Christian Komauer

Whereas the total noise level of an internal combustion engine supercharged by means of a gas-dynamic pressure-wave engine (1) (PWS) is usually only slightly higher than that of an engine supercharged by means of an exhaust-gas turbo supercharger (ETS), the narrow-band noise in the PWS rotational sound frequency range, the so-called PWS 'whistle', is considered troublesome. The absorption muffler (3) is an elongate body, the length (l.sub.1) of which is at least 10 times the rotor outside diameter of the PWS. The inside diameter (d) of the muffler (3) corresponds to the inside diameter of the exhaust pipe (4) and is at least 0.6 times the rotor outside diameter of the PWS. The thickness (S) of the insulating material, which directly surrounds the inside diameter (d) or inner cross-section (F) of the muffler (3), is at least 6 times the rotor outside diameter of the PWS divided by the number of cells of the PWS.

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Herrliberg, Switzerland

Tony Kollbrunner