A Computational Study of the Mixture Preparation in a Direct Injection Hydrogen Engine

Abstract

This paper reports the validation of a three-dimensional numerical simulation of the mixture preparation in a direct-injection hydrogen-fueled engine. Computational results from the commercial code CONVERGE are compared to the experimental data obtained from an optically accessible engine. The geometry used in the simulation is a passenger-car sized, four-stroke, spark-ignited engine. The simulation includes the geometry of the combustion chamber as well as the intake and exhaust ports. The hydrogen is supplied at 100 bar from a centrally located injector with a single-hole nozzle. The comparison between the simulation and experimental data is made on the central vertical plane. The fuel mole concentration and flow field are compared during the compression stroke at different crank angles. The comparison shows good agreement between the numerical and experimental results during the early stage of the compression stroke. The penetration of the jet and the interaction with the cylinder walls are correctly predicted. The fuel spreading is under predicted which results in differences in flow field and fuel mixture during the injection between experimental and numerical results. At the end of the injection, the fuel distribution shows some disagreement which gradually increases during the rest of the simulation.

3D CFD analysis of Mixture Formation in Direct-Injection Hydrogen-fueled Internal Combustion Engines

“…In the spark plug area, AVL FIRE only predicts a small diluted recirculation zone, whereas Ansys Fluent depicts a considerable amount of trapped fuel. Although the latter result might be supported by the correspondent experimental data provided, numerical results from the literature [18,19,20] appear aligned to those provided by AVL-Fire. The outcome from the contours at end of the compression stroke show that general mean bulk motion of the hydrogen is closely reproduced by the simulations, although diffusion seems underpredicted.…”

“…At -85°CA as the piston approaches the refined region of the TDC, AVL FIRE performs a better evaluation of the fuel penetration, although significantly lower fuel-air mixing emerges from the comparison with the experimental measurements. While the evolution of the jet penetration and the jet momentum connected to the large-scale convective transport can be described through averaged quantities, the mixing between fuel and bulk gas is strongly affected by the local levels of turbulence [18]. Until -85°CA, an acceptable agreement between the numerical and experimental results is observed, whereas increasing differences can be noticed at -55°CA.…”

“…Moreover, it must be pointed out that, during the PIV measurements, since SiO2 seedings occurs in the bulk gas (in the intake manifold), rather than in the fuel jet, a jet velocity underestimation is plausible to occur. In [18] Le Moine performs similar investigations comparing the computed velocity field against the PIV measurements for the high-tumble SOpHy case study. In this configuration, the tumble level has been increased by means of tumble-plates introduced in the intake ducts.…”

Experimental and numerical investigation of a direct injection spark ignition hydrogen engine for heavy-duty applications

“…However, in the RANS approach, only the mean phase averaged cycle is computed while knocking is visible on the complete pressure envelope and affects only the extreme cycles. As distribution [60] and that only with a LES approach a finer resolution of the turbulent scales can be achieved to solve the local mixing structures [61]. For PFI-MP10 point, at SA=RSA-7 CAD, a complementary 3D analysis is also conducted.…”

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

“…45 Given that the instantaneous mass flow rate was not experimentally measured, an assumed injection profile was adopted. 45 Given that the instantaneous mass flow rate was not experimentally measured, an assumed injection profile was adopted.…”