Piston ring-liner contact in an internal combustion engine highly influences the amount of friction, oil consumption and wear that occurs. Proper lubrication of this contact is, therefore, necessary and is an important research area for the engine manufacturers to improve fuel efficiency and achieve the emission reduction targets proposed by authorities. However, the lubricant film formed in piston ring-liner contact is very thin and its measurement is challenging. Although the computer simulations, a low cost tool, are widely used to estimate the piston ring-liner interactions, they require a robust data for the validation of the mathematical models. In the past several techniques based on optical or electrical characteristics of the lubricant have been developed and applied to measure lubricant film thickness in piston rings, such as capacitance, resistance, eddy current and laser induced fluorescence methods. The main characteristic of these techniques is that they are invasive and require access to the piston ring-liner contact, and so penetrate the cylinder liner. Hence these measurement methods disturb the nature of the contact and influence ring lubrication. This thesis demonstrates the development of a novel ultrasonic method for non-invasive measurement of oil films within the piston ring contacts and the feasibility of the technique on a reciprocating test rig and a fired engine. After successful implementations of ultrasonic technique, the investigation results showed that the ultrasound technique can be used for the piston ring film thickness measurement. The ultrasonically measured film thickness values were consistent with those of other published data in the literature. The effects of load, speed and viscosity on the lubricant film formation were shown in the reciprocator tests. The investigation of the single cylinder engine test showed that the bespoke ultrasonic sensors could survive at high temperature that liner exterior surface experienced. The minimum lubricant films between the compression ring and liner were measured during the engine's power stroke and were typically less than 1 μm at TDC and ~4 μm at mid stroke. It has been shown that the ultrasonic technique demonstrates significant promise as a non-invasive and effective tool to assess the lubricant condition within the ring-liner contact. As being insensitive to test environment and more compact technique compared to the current measurement technologies, the ultrasonic method has a potential to be employed in a test vehicle.

Internal combustion engines are perhaps the most ubiquitous power source in the modern world. Their heavy use in the vehicle industry and the current impetus to improve efficiency whilst reducing emissions means that OEMs are driving research to provide cleaner and 'greener' engines. Though significant effort is being channelled into teasing out improvements in thermodynamic Efficiency by such methods as pressure boosting and power management. the nature of an engine means many moving parts contribute to parasitic frictional loss. Of these interfaces. the reciprocating contacts between cylinder. piston rings and skirt are arguably subject to the most demanding tribological conditions within an engine. required to seal against the high temperature' combustion gases whilst supporting the large side loading inherent to the system. Given that the piston of an engine may perform this action hundreds of millions of times in its lifespan. the lubrication strategy and component design is of key importance in minimising wear frictional losses. Though the use of numerical simulation tools for improving design has seen significant growth as computational capabilities improve and provide cost advantages to full scale testing. robust validation methods are required to guide the development of the underlying models. The aim of this project was to assess the suitability of an ultrasonic method to monitor the condition of lubrication at the aforementioned contacts by measuring film thickness. Though various techniques involving optical and electrical principles have been employed in the past they generally require the cylinder of the engine to be penetrated and implementation. for the most part. is limited to the test cell. The results of investigations at the piston ring contact have shown that the ultrasonic technique can be used to measure lubricant film thickness and have shown the influence of cylinder pressure and reciprocating speed. Measurements correlate well with work by other authors using the alternative methods mentioned. giving confidence in the robustness of the method. Film measurements at the skirt have been also been successful. not only in quantifying the minimum films present. but also in detailing the profile of the film over its surface and enabling some of the secondary motions of the piston to be deduced. It has been shown that the ultrasonic technique offers the ability and freedom to measure film thickness within an operational engine whilst having the distinct advantage of limiting the degree structural modification required. It shows promise as a research tool and with further development. offers the potential to be incorporated into a lubricant monitoring and control System to help reduce friction losses and emissions.

This thesis presents a novel ultrasonic instrument for non-invasive and in-situ characterization of journal bearing lubricant viscosity. In particular, the application to journal bearings is described by non-invasively measuring the viscosity and localized power losses throughout operation. This ultrasonic viscometer is based on the reflection of polarized shear waves from a thin resonating coating layer to increase the measurement sensitivity, in comparison to conventional ultrasonic methods. This instrument allows for a full engine oil viscoelastic characterization in-situ. The book investigates the effects of temperature, pressure and shear rate, and describes in detail the ultrasonic setup and method. Further, it demonstrates that the same technique can be applied similarly to monitor the lubrication of other engine components. As such, it offers a unique instrument that can drive the research of oil formulations to improve engine performance and fulfill the requirements of international fuel economy regulations.

A NEW METHOD FOR DETECTING THE SHAPE OF A PISTON RING HAS BEEN DEVELOPED. THE METHOD USES THE MAGNITUDE OF A SURFACE WAVE ULTRASONIC ECHO TO PLOT THE QUALITY OF THE CONTACT BETWEEN A PISTON RING AND A GAGE BORE ON A POLAR GRAPH. THE TESTING METHOD AND THE RESULTS ARE DISCUSSED FOR INGLE-PIECE AND MULTIPIECE RINGS, AND FOR VARIOUS SURFACE TREATMENTS UTILIZED IN AUTOMOTIVE PISTON RINGS.

This book is a comprehensive and practical guide to the use of ultrasonic techniques for the characterization of fluids. Focusing on ultrasonic velocimetry, the author covers the basic topics and techniques necessaryfor successful ultrasound measurements on emulsions, dispersions, multiphase media, and viscoelastic/viscoplastic materials. Advanced techniques such as scattering, particle sizing, and automation are also presented. As a handbook for industrial and scientific use, Ultrasonic Techniques for Fluids Characterization is an indispensable guide to chemists and chemical engineers using ultrasound for research or process monitoring in the chemical, food processing, pharmaceutical, cosmetic, biotechnology,and fuels industries. Appeals to anyone using ultrasound to study fluids Provides the first detailed description of the ultrasound profiling technique for dispersions Describes new techniques for measuring phase transitions and nucleation, such as water/ice and oil/fat Presents the latest ultrasound techniques for particle sizing in concentrated systems Explains new techniques for compressibility measurements in dispersions and fluids, including cell suspensions Contains a detailed treatment of ultrasound scattering theory Written by one of the leading researchers in the field Includes over 350 references to the primary literature

Ultrasonic Measurement Methods describes methods used in ultrasonic measurements and covers topics ranging from radiated fields of ultrasonic transducers to the measurement of ultrasonic velocity and ultrasonic attenuation, along with the physical principles of measurements with electromagnetic-acoustic transducers (EMATs). Optical detection of ultrasound and measurement of the electrical characteristics of piezoelectric devices are also examined. Comprised of seven chapters, this volume begins with an analysis of the radiated fields of ultrasonic transducers, followed by a discussion on the measurement of ultrasonic velocity and attenuation. The next chapter describes the physical principles of measurement with EMATs and the advantages of such devices based on their couplant-free operation. Optical detection of ultrasound is then considered, together with the problem of measuring the electrical characteristics of piezoelectric resonators and standard methods for obtaining the equivalent electrical parameter values. The final chapter is devoted to ultrasonic pulse scattering in solids and highlights many fascinating examples of wave scattering, some of which are accompanied by theoretical analysis. This book will be of interest to physicists.