Experimental Measurement of the Time-Based Development of Oil Film Thickness, Lubricating Film Extent and Lubricant Transport in Crosshead Engines

This paper describes the design of a test apparatus which simulates the lubrication of large, slow, two-stroke marine engines in which the ring pack is lubricated by means of injectors supplying lubricant above the piston. The equipment is able to control lubricant injection parameters (volume, frequency, etc.) and employs capacitance based lubricant film thickness transducers to allow instantaneous oil film thickness and film extent around the compression ring to be investigated on a stroke-by-stroke basis. It is demonstrated that the equipment can be used to study the development of lubricating films on successive strokes under differing injection strategies. Time varying changes in lubricating film thickness and film extent have been measured and the rate at which the lubricant spreads across the cylinder wall has also been investigated. It has been observed that increases in oil-film thickness are strongly linked to the transition from starved to fully-flooded inlet conditions and that net lubricant transport rates along different parts of the cylinder can be evaluated from measured data.

A Multi-Wavelength Light Interference Method for the Measurement of Lubricating Film Thickness

A multi-wavelength light interference method for the measurement of lubricating film thickness was proposed for the improvement of convenience and accuracy of monochromatic light interferometry. Through the successive analysis of the hypothetical curves and the revised curves of three-wavelength light interference, the procedures of this method were discussed in detail. Then three-wavelength light interference method was applied to measure the lubricating film thickness of base oil under a specific condition. In comparison with the numerical results of Hamrock-Dowson formula, it was concluded that the multi-wavelength light interference method is applicable for the measurement of lubricating film thickness. With this method, the only requirement is the images which captured in stationary and purposed conditions, and higher measurement accuracy can be achieved.