Comparison of Ring-Liner Oil Film Thickness Resulting from Different Injector Designs in a Diesel Marine Engine Using an Ultrasound Measurement Method

Abstract

This is a repository copy of Comparison of ring-liner oil film thickness resulting from different injector designs in a diesel marine engine using an ultrasound measurement method.

Applying the Hilbert Envelope Method to Refine the Ultrasonic Technique for Piston Ring Oil Film Thickness Measurements in a Marine Diesel Engine

“…In this test case, the minimum reflection coefficient is around 0.75 and can be used to define the minimum OFT (Equation 5). Further to the main features, there are several secondary features (as labeled in Figure 7) that are similar to those in other ultrasonic works [10], [38], [39]:…”

“…The technique has also been applied to a marine diesel engine; in [35] a sensor was mounted behind a piston ring for measurements over the whole piston stroke. Whilst in the previous work on the RTX-6 engine in [10], the minimum OFT for the first ring at the TDC ranged from 5-10 μm at full engine loading. The piezoelectric sensors produce an average measurement over the complete surface of the sensor, therefore, the size of the sensor relative to the piston ring width has a significant impact on the results.…”

“…As well as the 'Control sensor', an ultrasonic sensor that was intentionally instrumented above all piston rings at their TDC positions to study the effect of cylinder liner distortion, see Figure 3 for a visualization of their respective locations. The Top Ring sensor and the other longitudinal sensors are also covered in [10].…”

“…Refining the interaction between the piston/ring pack and cylinder liner in combination with using alternative fuels such as liquefied natural gas, methanol or biomethanol [8] and refining the combustion cycle [9] provides a viable route to meet environmental regulations. This article follows the work given in [10] on an RTX-6 Winterthur Gas & Diesel test engine in which a series of ultrasonic sensors were instrumented close to the top dead center (TDC) of the piston and three lubricant injection configurations were evaluated. The ultrasonic sensors provided a methodology to show a novel lubricant injector design led to thicker oil films between the piston ring and liner by a reduction in lubricant lost to the exhaust manifold.…”

“…Figure 1 RTX-6 test engine reproduced from [10]. © SAE International The OFT calculated from the ultrasonic technique is highly dependent on the speed of sound and density of the oil (see Equation 5).…”