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Cycle to Cycle Variation Study in a Dual Fuel Operated Engine

Convergent Science Inc.-Sameera Wijeyakulasuriya
GE, Global Research Center-ShyamSundar Pasunurthi, Ravichandra Jupudi, Sreenivasa Rao Gubba, Roy Primus, Adam Klingbeil
Published 2017-03-28 by SAE International in United States
The standard capability of engine experimental studies is that ensemble averaged quantities like in-cylinder pressure from multiple cycles and emissions are reported and the cycle to cycle variation (CCV) of indicated mean effective pressure (IMEP) is captured from many consecutive combustion cycles for each test condition. However, obtaining 3D spatial distribution of all the relevant quantities such as fuel-air mixing, temperature, turbulence levels and emissions from such experiments is a challenging task. Computational Fluid Dynamics (CFD) simulations of engine flow and combustion can be used effectively to visualize such 3D spatial distributions. A dual fuel engine is considered in the current study, with manifold injected natural gas (NG) and direct injected diesel pilot for ignition. Multiple engine cycles in 3D are simulated in series like in the experiments to investigate the potential of high fidelity RANS simulations coupled with detailed chemistry, to accurately predict the CCV.Cycle to cycle variation (CCV) is expected to be due to variabilities in operating and boundary conditions, in-cylinder stratification of diesel and natural gas fuels, variation in in-cylinder turbulence levels…
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Application of High Performance Computing for Simulating Cycle-to-Cycle Variation in Dual-Fuel Combustion Engines

Convergent Science Inc.-Sameera Wijeyakulasuriya
GE Global Research Center-Ravichandra S. Jupudi, Roy Primus, Adam E. Klingbeil, Bhaskar Tamma
Published 2016-04-05 by SAE International in United States
Interest in operational cost reduction is driving engine manufacturers to consider low-cost fuel substitution in heavy-duty diesel engines. These dual-fuel (DF) engines could be operated either in diesel-only mode or operated with premixed natural gas (NG) ignited by a pilot flame of compression-ignited direct-injected diesel fuel. Under certain conditions, dual-fuel operation can result in increased cycle-to-cycle variability (CCV) during combustion. CFD can greatly help in understanding and identifying critical parameters influencing CCV. Innovative modelling techniques and large computing resources are needed to investigate the factors affecting CCV in dual-fuel engines. This paper discusses the use of the High Performance Computing resource Titan, at Oak Ridge National Laboratory, to investigate CCV of a dual-fuel engine. The CONVERGE CFD software was used to simulate multiple, parallel single cycles of dual-fuel combustion with perturbed operating parameters and boundary conditions. Perturbations associated with a single parameter can be studied using samples distributed according to a one dimensional interpolation rule. However, extending such techniques to a multidimensional context is a challenge since the straight forward tensorization leads to an exponential…
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Characterization of Flow Asymmetry During the Compression Stroke Using Swirl-Plane PIV in a Light-Duty Optical Diesel Engine with the Re-entrant Piston Bowl Geometry

SAE International Journal of Engines

Convergent Science, Inc.-Sameera Wijeyakulasuriya, Saurav Mitra, P. K. Senecal
Sandia National Laboratories-Kan Zha, Stephen Busch, Paul C. Miles
  • Journal Article
  • 2015-01-1699
Published 2015-04-14 by SAE International in United States
Flow field asymmetry can lead to an asymmetric mixture preparation in Diesel engines. To understand the evolution of this asymmetry, it is necessary to characterize the in-cylinder flow over the full compression stroke. Moreover, since bowl-in-piston cylinder geometries can substantially impact the in-cylinder flow, characterization of these flows requires the use of geometrically correct pistons. In this work, the flow has been visualized via a transparent piston top with a realistic bowl geometry, which causes severe experimental difficulties due to the spatial and temporal variation of the optical distortion. An advanced optical distortion correction method is described to allow reliable particle image velocimetry (PIV) measurements through the full compression stroke.Based on the ensemble-averaged velocity results, flow asymmetry characterized by the swirl center offset and the associated tilting of the vortex axis is quantified. The observed vertical tilting of swirl center axis is similar for tested swirl ratios (2.2 and 3.5), indicating that the details of the intake flows are not of primary importance to the late-compression mean flow asymmetry. Instead, the geometry of the piston…
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