Numerical Study of Lean-Direct Injection Combustor With Discrete-Jet Swirlers Using Reynolds Stress Model

Abstract

The flowfield in a lean-direct injection (LDI) combustor with discrete-jet swirlers is described and analyzed using a computational fluid dynamics (CFD) code with a Reynolds stress turbulence model (RSTM). The results from the RSTM are compared to time-averaged laser-Doppler velocimetry (LDV) data, as well as results from the National Combustion Code (NCC) that has a cubic nonlinear κ-ε turbulence model, and from the KIVA code using the standard κ-ε model. The comparisons of results indicate that the RSTM accurately describes the flow details and resolves recirculation zones and high velocity gradients while the κ-ε models are unable to capture most flow structures. This confirms that, within the Reynolds averaging approach, the higher-order RSTM is preferred for simulating complex flowfields where separations, strong anisotropy, and high swirl are present.

Diesel Engine Valve Clearance Detection Using Acoustic Emission

“…Both large-scale turbulence and small-scale turbulence have a drastic result on combustion, flow-mixing, and heat-transfer in an engine [9]. The major source of energy for turbulent velocity fluctuations is shear in the mean flow, for example, jets [10], but the velocity gradient at the wall in the boundary layer produces large vortices which are unstable inside the chamber and eventually break down into additional turbulent motion. The fluid flow through the orifice of the injector is associated with four components.…”

Reynolds-stress turbulence model in the KIVA code for engine simulation

“…Quantitative comparisons showing the improvement experienced with the RSTM can be found in Yang et al [2003b] and Teo et al [2001], which describe simulation results for an LDI combustor with discrete-jet swirlers using the RSTM. The comparisons were made to LDV data [Jeng et al, 2001] as well as results from the National Combustor Code using a cubic nonlinear k-ε model [Iannetti et al, 2001a] Along these lines, this study focuses on the application of a reduced, or simplified, kinetic mechanism, designed primarily for concentrations of nitric oxide in Jet-A combustion, that was synthesized from a larger, detailed mechanism for propane (a detailed mechanism does not exist for Jet-A combustion).…”