During a wheel slide the frictional heat generated at the contact interface causes intense heating of the adjacent wheel material. If this material exceeds the austenitising temperature and then cools quickly enough, it can transform into martensite, which may ultimately crack and cause wheel failure. A knowledge of the distribution of the heat partitioned into the wheel and the rail and the resulting temperature fields is critical to developing designs to minimize these deleterious effects. A number of theoretical solutions have appeared in the literature to model the thermal aspects of this phenomenon. The objective of this investigation was to examine the limitations of these solutions by comparing them to the results of a finite element analysis that does not incorporate many of the simplifying assumptions on which these solutions are based. It was found that these simplified solutions can produce unrealistic results under some circumstances.

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An infrared radiometer, which incorporated three optical paths and operated between 3.5-4.0 I'm, was used to obtain transient surface temperatures in a fired engine. An integrated form of the equation of radiative transfer was applied to each optical path allowing gas emission, gas absorption and deposit surface radiation within the combustion-chamber to be characterized during a single cycle. Measurements of a simulated deposit were made at various temperatures and spark advance with the engine fired on methane and again on gasoline. Radiative characteristics of the combustion gases such as absorption and emission were investigated at several different operating conditions. A maximum error of 6% was found for temperature measurements between 660 and 900 Kelvins.Using a fast surface thermocouple with its junction located at the inner surface of the combustionchamber wall, two combustion-chamber deposits were accumulated for different lengths of time. Deposit surface and interface temperatures were investigated at several different operating conditions for each deposit. Utilizing the experimentally obtained deposit surface and interface temperatures, deposit thermal conductivity (k) and heat capacity (Qc) were determined via a computational model which treated k as a function of temperature. Values obtained for k and oc were well within the range of those reported for various forms of graphite.