The influence of operating conditions on combustion chamber deposit surface structure, deposit thickness and thermal properties

In this work the surface structure of combustion chamber deposits (CCD) on the piston top and the cylinder head is described. By means of an optical profiler the roughness and maximum structure heights are measured. Scanning electron microscope images allow evaluating the structure of the deposits on the surface. The oil influence on CCD formation is assessed using energy-dispersive X-ray spectroscopy to quantify typical oil additives such as Mg, Ca or Zn in the deposits. By means of direct numerical simulation the influence of the CCD structure on near wall flow and hence on convective heat transfer is assessed. With fast surface thermocouples the temperature fluctuation on the cylinder head is measured. Applying two different model approaches—Hopwood and two-layer-model—the CCD layer thickness is calculated. By correlating the results with layer thickness measurements by the above mentioned optical profiler the values of the thermal conductivity for the CCD layers are calculated.

Language

  • English

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  • Accession Number: 01689176
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 23 2018 3:04PM