Affiliation:
1. Department of Mechanical Engineering, The University of Melbourne, Parkville, Melbourne 3010, Victoria, Australia
Abstract
This study investigates the impact of the near-wall temperature gradient on hydrogen auto-ignition characteristics using one-dimensional (1D) fully resolved simulations. Ten cases are simulated, one featuring normal combustion and the other nine simulating auto-ignitive combustion with different initial pressures, equivalence ratios, and near-wall temperature gradients. The simulations show that the near-wall temperature gradient greatly affects the onset and intensity of the auto-ignition event. For cases with the initial conditions of 833.3 K and 15 bar, a small near-wall temperature gradient delays the timing of auto-ignition and places the auto-ignition kernel further away from the wall, facilitating deflagration-to-detonation transition of the auto-ignitive flame. This leads to a large increase in pressure oscillations within the domain and heat flux to the wall. When the initial conditions are changed to 900 K and 20 bar, the magnitude of the near-wall temperature gradient also affects the number of auto-ignition events, leading to a significant impact on the wall heat flux. The results suggest that an accurate modeling of the near-wall temperature gradient is necessary for the simulations of hydrogen end-gas auto-ignition. This requires special considerations in the near-wall region and a careful selection of the wall heat transfer model in Computational Fluid Dynamics (CFD) tools, such as Reynolds-Averaged Navier–Stokes (RANS) and Large-Eddy Simulation (LES).
Funder
Australia Research Council
China Scholarship Council
Subject
Condensed Matter Physics,Fluid Flow and Transfer Processes,Mechanics of Materials,Computational Mechanics,Mechanical Engineering
Cited by
5 articles.
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