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Atomization and Sprays

Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

Institutional price:	$787.00
Issues per year:	8

Best Paper Award Selection - Editorial Board Site

2002, Volume12

363 pages

DOI: 10.1615/AtomizSpr.v12.i123

Issue price - $225.00

THE SPRAY-INDUCED FLOW AND ITS EFFECT ON THE TURBULENT CHARACTERISTIC COMBUSTION TIME IN Dl DIESEL ENGINES

Franz X. Tanner
Department of Mathematical Sciences, Michigan Technological University, Houghton, Michigan 49931-1295, USA

Rolf Reitz
University of Wisconsin Madison

ABSTRACT

In direct-injection diesel engines the combustion process is strongly influenced by the turbulence of the spray-induced flow. This flow is transient in nature and, therefore, the equilibrium-based k-e-type turbulence models yield inaccurate predictions of the turbulence mixing time scales. This requires adjustments of the turbulence characteristic combustion time by means of the coefficient C_M, in order to match experimental cylinder pressures of different engines. These adjustments are explained in terms of nonequilibrium turbulence behavior of the spray-induced flow. A relation between the spatially averaged equilibrium and nonequilibrium turbulence time scales is derived which leads to a scaling law between the different engines. In particular, the value of C_M for one engine can be obtained from the optimum C_M of another engine, provided the turbulence determining integral length scales are known. This scaling behavior has been demonstrated for four substantially different engines by comparing the tuned values of C_M with the computed scaling factors, and favorable agreement has been obtained.