Spatial Variation of Heat Transfer to Pistons and Liners of Some Medium Speed Diesel Engines

Abstract

Heat transfer coefficients have been measured on the gas side of pistons and liners, the water side of liners, and the oil side of pistons. A significant radial variation in heat transfer across the piston crown has been found. The position of the maximum heat transfer coefficient appears to be coincident with the maximum air concentration, or the position the tips of the fuel sprays have reached at the time of ignition, and the radial variation of heat transfer is possibly related to the amount of fuel burnt at each radius. For four-stroke engines, equations are presented to describe this variation. Heat transfer coefficients at the exposed section of the liner have been found to be similar to the values at the outer edge of the piston. Heat transfer between piston undercrown and cooling oil has been measured for various types of cooling arrangement and, for jet cooling, an expression has been suggested for the heat transfer coefficient. Equations have also been derived to enable coefficients to be predicted for heat transfer from liner to cooling water.

Experimental Assessment of Instantaneous Heat Transfer in the Combustion Chamber and Exhaust Manifold Walls of Air-Cooled Direct Injection Diesel Engine

“…The boundary conditions for Eq. (5) can then be written as (6) where is the distance from the wall surface of the indepth thermocouple, which provides constant temperature readings.…”

“…This importance has been well recognized from the early stages of engine development [1 -3]. Results from various theoretical and experimental research efforts on this field have been presented during the last decades in the literature by several researchers [4][5][6][7]. It is generally recognized that the problem is quite difficult and many of its aspects still remain to be analyzed and elucidated.…”

An Area-Average Correlation for Oil-Jet Cooling of Automotive Pistons

“…The only available heat transfer correlation, specific to piston oil-jet cooling, is the following correlation, circa 1971, suggested by Seale and Taylor [1] (see also Rakopoulos et al [2]), for medium-size (B « 200 -450mm) direct-injection (DI) diesel engines:…”

Measurements and analysis of load and speed effects on the instantaneous wall heat fluxes in a direct injection air-cooled diesel engine

“…Various theoretical and experimental research e!orts on this subject have been presented during the last decades (Annand, 1963;Annand andMa, 1970}1971;Seale andTaylor, 1970}1971;Whitehouse, 1970}1971;French, 1972;Sitkei, 1974;Kamel and Watson, 1979;Prasad and Samria, 1990;Kouremenos et al, 1991). This subject, while being a desirable and probably necessary element in modern engine technology, it is quite di$cult and many of its aspects have not been adequately studied up to this time.…”