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Measurement of oil film thickness between piston rings and cylinder liner was conducted on a single cylinder version of a Cummins L-10 diesel engine using a laser induced fluorescence technique. The oil was illuminated with blue laser light (λ=442 nm) that causes the oil to fluoresce at a longer characteristic wavelength (λ=500 nm). This fluorescent light intensity is proportional to oil film thickness. A single fiber (50 μm core) was used to carry the laser light to the oil and to return the fluorescent light back to a photomultiplier tube. The paper presents results of oil film thickness measured under motored engine conditions for varying engine speeds, intake boost pressures and cylinder liner temperatures. The following conclusions were drawn from the experimental data. Oil film thickness increases with engine speed showing hydrodynamic lubrication. An increase in liner temperature decreases oil film thickness.

Instantaneous heat flux rates were measured in a spark ignited CFR engine. A new heat flux probe was used which had seven thin film platinum resistance thermometers, spaced 1 mm apart, on a Macor substrate. Instantaneous heat flux was measured at each sensor location and the integral length scale of heat flux was calculated from the spatial cross correlation data. A swirl flow condition was generated by use of a shrouded intake valve, and tumble flow was created by rotating the shrouded valve 90°. An unshrouded valve gave a more quiescent flow condition. Under motoring conditions, peak heat flux was 70% higher for swirl flow conditions than quiescent flow conditions, and the total heat rejected during the closed portion of the cycle was 50% higher with the swirl flow than the quiescent flow. The peak heat flux for swirl flow compared to tumble flow was 30% higher and the total heat rejection was 10% greater.

A new instrument for measurement of diesel in-cylinder radiation heat transfer has been designed, calibrated, and tested in a single cylinder, open chamber, turbocharged diesel engine. The unique feature of the instrument is that it measures the total radiation flux over the entire hemisphere, rather than being restricted to a finite acceptance angle of less than 2π steradians as have previous instruments. The paper gives the instrument design details and shows that a combination of polycrystalline alumina and sapphire gives an optimum receiver optics design. However a solution to the problem of bonding these two materials was not found. Thus an all polycrystalline alumina receiver was used in the prototype instrument. Results using the prototype show that keeping the receiver free of soot is a problem for an all polycrystalline alumina design. Data were thus corrected for window deposits by post-experiment calibration of the dirty receiver.

Six specially blended diesel fuels were tested in an open chamber TACOM-LABECO single cylinder diesel engine at turbocharged conditions, to determine if the chemical composition of the volatile fraction of the fuels had a significant effect on performance and emissions. The tests show that for this engine, which has a moderately high swirl and a four hole nozzle, the effects are very small. Additional tests were run, with these same fuels, in a homogenous autoigniting mode to determine if ignition trends were similar to those produced by the heterogeneous diesel ignition. The ignition delay trends were found to follow the same pattern, reinforcing the conclusion that the fuel combustion in the diesel was not significantly affected by distillation effects during the vaporization process.

A discussion of reciprocating engine combustion research needs is presented. Results of a survey ranking 31 specific research topics are also given. The twenty-three respondents gave the five highest grades to; particulate formation and oxidation mechanisms, high temperature ring friction, end gas heat transfer and high pressure transient fuel spray studies.