Numerical Investigation of Direct Gas Injection in an Optical Internal Combustion Engine

Deshmukh, Abhishek Y.; Falkenstein, Tobias; Pitsch, Heinz; Khosravi, Maziar; Bebber, David van; Klaas, Michael; Schröeder, Wolfgang

doi:10.4271/2018-01-0171

Cited by 10 publications

(17 citation statements)

References 32 publications

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“…The first case is a temporal evolution of a gas jet in quiescent air 30 and the second case is a cold flow simulation of full engine cycle with injection. 24…”

Section: Validation: Dcs Modelmentioning

confidence: 99%

“…Consequently, the resulting shocks and discontinuities have a great impact on the flow field within the cylinder. 8,9 Due to the small geometries, high velocities, and the related small time scales of the injection process, an experimental investigation is often difficult. 10 The conventional single- or multi-hole inwardly opening DI-injectors with cylindrical nozzles are prone to be opened by the cylinder pressure if the injection pressure is lower.…”

Section: Introductionmentioning

confidence: 99%

“…Despite many studies on the fundamental processes of gas injection and the application in the engine, measurements of the in-cylinder flow field and mixing behavior are very challenging, owing to the strong interaction of the highly dynamic gas jet with the surrounding flow field. 9,24 As discussed before, previous investigations also emphasized the need for optimization of injection and mixture formation process for different injector designs and their orientations in the combustion chamber through numerical simulations to improve combustion efficiency and reduce pollutant emissions. Therefore, accurate predictive simulations are required for such design, development, and optimization of DI-CNG engines.…”

Section: Introductionmentioning

confidence: 99%

“…However, the model neglected the upstream nozzle geometry, which may be important for the nozzle flow. Recently, Deshmukh et al 9,24 developed a mapped boundary condition (MBC) approach as the injector model for a full cycle engine simulation. In this approach, a stand-alone nozzle-flow LES was carried out for given pressure ratios, and the variables were recorded at the mapping location after the flow reached quasi -steady-state.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, the injector model is developed and validated against LES of nozzle flow for different pressure ratios. The temporal evolution of the hollow-cone gas jet into ambient air with fixed and moving injector needle in the model is evaluated against Schlieren experiments and three-dimensional (3-D) simulations reported in Deshmukh et al 30 The model is then applied to a full cycle engine simulation and compared with PIV measurements and simulations with the MBC approach previously published in Deshmukh et al 24…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A quasi-one-dimensional model for an outwardly opening poppet-type direct gas injector for internal combustion engines

Deshmukh

Giefer

Goeb

et al. 2019

International Journal of Engine Research

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Direct injection of compressed natural gas in internal combustion engines is a promising technology to achieve high indicated thermal efficiency and, at the same time, reduce harmful exhaust gas emissions using relatively low-cost fuel. However, the design and analysis of direct injection–compressed natural gas systems are challenging due to small injector geometries and high-speed gas flows including shocks and discontinuities. The injector design typically involves either a multi-hole configuration with inwardly opening needle or an outwardly opening poppet-type valve with small geometries, which make accessing the near-nozzle-flow field difficult in experiments. Therefore, predictive simulations can be helpful in the design and development processes. Simulations of the gas injection process are, however, computationally very expensive, as gas passages of the order of micrometers combined with a high Mach number compressible gas flow result in very small simulation time steps of the order of nanoseconds, increasing the overall computational wall time. With substantial differences between in-nozzle and in-cylinder length and velocity scales, simultaneous simulation of both regions becomes computationally expensive. Therefore, in this work, a quasi-one-dimensional nozzle-flow model for an outwardly opening poppet-type injector is developed. The model is validated by comparison with high-fidelity large-eddy simulation results for different nozzle pressure ratios. The quasi-one-dimensional nozzle-flow model is dynamically coupled to a three-dimensional flow solver through source terms in the governing equations, named as dynamically coupled source model. The dynamically coupled source model is then applied to a temporal gas jet evolution case and a cold flow engine case. The results show that the dynamically coupled source model can reasonably predict the gas jet behavior in both cases. All simulations using the new model led to reductions of computational wall time by a factor of 5 or higher.

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“…The first case is a temporal evolution of a gas jet in quiescent air 30 and the second case is a cold flow simulation of full engine cycle with injection. 24…”

Section: Validation: Dcs Modelmentioning

confidence: 99%