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A laser fluorescent diagnostic method was employed to measure lubricant film thickness on the cylinder wall/piston interface of two engines. The system output signal was calibrated using lubricant samples of known thickness, and by comparison of a known piston ring profile to measured lubricant film contours. Agreement of the results of the two calibration methods was within 5%. A relative calibration was performed with three oils having different additive packages, and with an oil contaminated through use in a commercially operated engine. The calibration coefficients for the oils, relating output voltage to film thickness, varied within a factor up to two, depending on lubricant type and age. The laser fluorescent apparatus was installed for use with a single cylinder test version of the Cummins VT-903 diesel engine. An optical passage was created through the block and cylinder wall using a quartz window.

A technique of calculating the evolution of turbulence during the combustion phase of a reciprocating engine cycle is presented. The method is based on a local linearization of the full non-linear equations of motion. It is valid when the turbulence is distorted more rapidly by the changes in mean flows than it interacts with itself. The theory requires as input strain rates of the deterministic mean motion, and the initial state of turbulence. Calculations are presented for the particular case of a cylindrical chamber geometry. In the burning process it is assumed that the spark plug is located on the cylinder axis and the strain field is that established by the flame front. The theory calculates the turbulence parameters during the combustion period. Combustion rates, and durations, as a function of equivalence ratio and the initial turbulent and thermodynamic conditions.