Diesel Cylinder Gas-Side Heat Flux to a Ceramic Surface

摘要

Results of four research projects each dealing with instantaneous heat flux to the cylinder head of reciprocating engine are given. The projects are: heat flux to the cylinder head of a reciprocating engine are given. The projects are: heat flux measurements in a diesel engine with variations in injection pressure, nozzle tips and swirl; development of instrumentation for radiation measurements in a diesel cylinder; heat flux measurements to various surfaces on the head of diesel engine including a normaly cooled metal surface, an insulated metal surface and a zirconia surface; and initial attempts to simultaneously measure the fluid motion and heat flux in a motored engine boundary layer. The variation of injection pressure nozzle tips and swirl in a direct injection diesel showed strong coupling between combustion and heat flux. An instrument for radiation measurement which uses a wall jet to reduce convection is described. Compression of the jet by the combustion heat release prevents zeroing of the convection. The major portion of the research was devoted to heat flux measurements to the surface of an instrumentation plug in the head of a single TACOM-LABECO diesel. Comparisons made between data for insulated and uninsulated surfaces show that the hot metal surface gave reduced time averaged heat transfer, but gave a higher peak heat flux than a normally cooled surface. Data for zirconia plate surface gave reduced time averaged heat transfer, but gave a higher peak heat flux than a normally cooled surface. Data for zirconia plate surface showed a reduction in peak flux which was larger than predicted from the rise in surface temperature alone.