Origins of noise and vibration in vee form diesel engines with emphasis on piston slap

Haddad, Sulaiman David (1974) Origins of noise and vibration in vee form diesel engines with emphasis on piston slap. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The investigations described in this thesis deal with Vee engine vibration and noise characteristics induced by combustion and piston impact forces in both conventional and low noise engine structures. It has been shown that the bank to bank mode of Vee engine vibration is basically due to piston slap excitation while the conical mode, mainly resulting from combustion, is accentuated by piston to bore oil film pressure. These modes were also seen to persist on specifically designed low noise engine structures. Cylinder block- vibration, and the resultant noise radiated, is mainly due to piston slap. Simulations of piston slap on an experimental rig and an analogue computer have illustrated that the rate of rise of the piston sideways force is the most important parameter controlling the resultant cylinder block vibration. Block vibration acceleration is proportional to the logarithm of the rate of rise of the side force. Oscillographic and change of parameter studies have shown that piston slap can be as important a source of noise as combustion. Up to 3 dBA reduction of the overall engine noise, in the frequency range from 1000 Hz upwards, is practicable in existing engines by minimising piston slap. Study of piston behaviour in a running engine has shown that piston movement in the bore initiates dynamic pressures which are due to both squeeze film and hydrodynamic effects. The impulsive squeeze film pressure (i)

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