A 3D-CFD Numerical Approach for Combustion Simulations of Spark Ignition Engines Fuelled with Hydrogen: A Preliminary Analysis

Abstract

<div class="section abstract"><div class="htmlview paragraph">With growing concern about global warming, alternatives to fossil fuels in internal combustion engines are searched. In this context, hydrogen is one of the most interesting fuels as it shows excellent combustion properties such as laminar flame speed and energy density. In this work a CFD methodology for 3D-CFD in-cylinder simulations of engine combustion is proposed and its predictive capabilities are validated against test-bench data from a direct injection spark-ignition (DISI) prototype. The original engine is a naturally aspirated, single cylinder compression ignition (Diesel fueled) unit. It is modified substituting the Diesel injector with a spark plug, adding two direct gas injectors, and lowering the compression ratio to run with hydrogen fuel. A 3D-CFD model is built, embedding in-house developed ignition and heat transfer models besides G-equation one for combustion. Three different lean-burn conditions are selected among the tested ones for the validation of the numerical framework. The investigated conditions are characterized by the same revving speed (3000 rpm) but different equivalence ratios (0.4, 0.6 and 0.8, respectively). A good agreement with the experimental dataset is observed, confirming the validity of the proposed CFD approach, and opening the possibility of further virtual optimizations of the engine.</div></div>

Hydrogen, methane and one of their fuel blends combustion: CFD analysis and numerical-experimental comparisons of fixed and mobile applications

“…As for the Turbulent Flame Speed Closure, this model requires the definition of both laminar and turbulent flame speed: it identifies the position of the flame front and propagates it at the TFS specified, so it suitable for premixed and partially premixed combustion simulations. The CC-TFC model behaviour will be examined on the hydrogen combustion in the internal combustion engine on which, more details can be found in [26]. The laminar flame speed correlation used is the one proposed by Verhelst et al [27], while the Peters correlation is used for the turbulent flame speed.…”

“…The hydrogen combustion development is analysed with unsteady-RANS simulations. The initial conditions considered for pressure, temperature, velocity, chemical composition, turbulent kinetic energy and its dissipation are the result of a full cycle simulation including 𝐻 2 direct injection whose details are reported in [26]. As for the boundary conditions, for model assessment wall heat transfer is neglected setting all the walls as adiabatic walls.…”