Numerical Methodology for Optimization of Compression-Ignited Engines Considering Combustion Noise Control

Broatch, A.; Novella, Ricardo; Gómez-Soriano, Josep; Pal, Pinaki; Som, Sibendu

doi:10.4271/2018-01-0193

Cited by 32 publications

(21 citation statements)

References 63 publications

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“…The predicted amplitude of these oscillations are similar to the averaged value of 100 measured cycles. These results have encouraged the authors to explore U-RANS modelling in order to define trends in the Diesel knock phenomenon for several operating conditions and design parameters [25].…”

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confidence: 99%

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

et al. 2018

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Diesel combustion noise has become a crucial aspect for the engine manufacturers due to its impact on human health and influence on the customer purchasing decision. The interaction of the pressure waves after mixture self-ignition induces cavity resonances inside the combustion chamber. This complex phenomenon produces high-frequency pressure oscillations, hence traditional in-cylinder measurements do not provide enough information to characterise the in-cylinder acoustic field. In this paper, a numerical methodology is proposed for assessing the Diesel combustion as a noise source and to overcome measurement limitations. An optimisation procedure is also presented in order to determine the numerical calculation parameters, boundary conditions definition and initialization. Results show that local flow conditions at the start of combustion have a strong influence on the acoustic response of the in-cylinder noise source. These particular conditions are only achievable by the proposed methodology which considers entire engine cycle simulations with the complete cylinder domain. Therefore, traditional Computational Fluid Dynamic (CFD) approaches, such those used for predicting combustion stability or pollutant emissions, are not suitable for reproducing the physical mechanisms of noise generation and they cannot be used for acoustic purposes. The reliability of the proposed methodology to simulate the acoustic field accurately inside the combustion chamber has been validated by comparison with experiments.

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Section: List Of Symbolsmentioning

confidence: 99%

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

et al. 2018

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“…This configuration has proven to accurately reproduce the in-cylinder pressure field oscillations over a wide range of operation conditions and combustion regimes [26,50,51].…”

Section: Numerical Model Set-upmentioning

confidence: 99%

“…However, requirements in terms of mesh resolution and runtime are prohibitive for practical applications. Furthermore, reproducing pressure effects of knock-local pressure oscillations-is extremely demanding [25][26][27], further compromising its application to the industry environment.The main objective of this paper is therefore to develop and validate a robust knock simulation methodology based on 3D CFD modelling that allow to include knock systematically in the design process of future automotive engines. In order to achieve this target, several simplifications should be applied.…”

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Computational Methodology for Knocking Combustion Analysis in Compression-Ignited Advanced Concepts

2018

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In the present work, a numerical methodology based on three-dimensional (3D) computational fluid dynamics (CFD) was developed to predict knock in a 2-Stroke engine operating with gasoline Partially Premixed Combustion (PPC) concept. Single-cycle Unsteady Reynolds-Averaged Navier Stokes (URANS) simulations using the renormalization group (RNG) k − ε model were performed in parallel while the initial conditions are accordingly perturbed in order to imitate the variability in the in-cylinder conditions due to engine operation. Results showed a good agreement between experiment and CFD simulation with respect to cycle-averaged and deviation of the ignition timing, combustion phasing, peak pressure magnitude and location. Moreover, the numerical method was also demonstrated to be capable of predicting knock features, such as maximum pressure rise rate and knock intensity, with good accuracy. Finally, the CFD solution allowed to give more insight about in-cylinder processes that lead to the knocking combustion and its subsequent effects.In particular, PPC operated with low reacting fuels, such as gasoline, have shown encouraging results to achieve very low pollutant emissions while maintaining, or even improving, the thermal efficiency [10][11][12]. Indeed, this combustion concept operated in an innovative 2-Stroke high speed direct injection (HSDI) compression-ignited (CI) engine [13] offers a good flexibility to control the combustion timing and to extent the load range [14][15][16].This concept operates between completely premixed and fully diffusive conditions, whereby low pollutant emissions may be attained. However, to achieve these conditions while retaining an accurate combustion timing control with the injection event remains as the main drawback of this particular system when operating under transient conditions.Despite the attractive benefits of this engine system, its complexity due to the large number of parameters to be managed requires the use of optimization techniques which ensure greater flexibility, speed and lower costs than purely experimental procedures.In this framework, the use of computational fluid dynamics (CFD) simulations is nowadays widely established in both the research community and the automotive industry. Here, aspects such as the simulation of turbulence and how it couples with the chemistry [17] are still the main limiting factors for reproducing the reacting flow field accurately. Since the requirements in both fields tend to differ, specially in terms of time available, the approaches used are also usually different. While in the industry sector, simulations are based on Unsteady Reynolds-averaged Navier-Stokes (URANS) turbulence modelling [18,19] and flamelet-based combustion models [20] owing its lower computational demands, the research community prefer to resort to high-fidelity combustion models and more complex turbulence schemes such as Large Eddy Simulations (LES) [21] or Direct Numerical Simulations (DNS) [22].Although the industry standard tends to simplify the simulatio...

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“…The renormalization group (RNG) k − model [27] coupled with the heat transfer approach proposed by Angelberger et al [28] was used for modelling the turbulent flow features. This approach has proven to accurately reproduce the in-cylinder pressure field oscillations over a wide range of operation conditions and combustion regimes [29,30]. Therefore, the macroscopic oscillations of the pressure waves due to the autoignition of the premixed fuel-air blend are still successfully reproduced, even if the local fluctuation components of the Navier-Stokes equations are neglected.…”

Section: Numerical Model Setupmentioning

confidence: 99%

Potential of dual spray injectors for optimising the noise emission of gasoline partially premixed combustion in a 2-stroke HSDI CI engine

Broatch

Novella

García-Tíscar

et al. 2018

Applied Thermal Engineering

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This paper evaluates the potential advantages of introducing a new injector concept with a dual set of orifices in a 2-stroke engine operating with gasoline partially premixed combustion (PPC gasoline), specially in terms of combustion noise reduction. The injector is based on a configuration with two concentric needle valves and dual actuators, which allows to switch among two independent crowns of holes. The first set of orifices is controlled by the primary needle valve while an additional needle valve manages the secondary holes crown. Moreover, both valves are coupled with the two actuators separately, providing enhanced selective control over injection with an extra degree of freedom. In this investigation, a combination of Computational Fluid Dynamics (CFD) simulations and the Design of Experiments (DoE) technique is proposed with the specific purpose of optimizing this new injector configuration. In addition to determining the most convenient design, this method is extremely useful to establish cause/effect relationships between the injection design parameters and their impact on the engine performance and emissions. Results show how this solution could increase the operating range of the PPC gasoline concept by improving the combustion stability while acoustic emissions are reduced.

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Numerical Methodology for Optimization of Compression-Ignited Engines Considering Combustion Noise Control

Abstract: I t is challenging to develop highly efficient and clean engines while meeting user expectations in terms of performance, comfort and drivability. One of the critical aspects in this regard is combustion noise control. Combustion noise accounts for about 40 percent of the

Cited by 32 publications

References 63 publications

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

Computational Methodology for Knocking Combustion Analysis in Compression-Ignited Advanced Concepts

Potential of dual spray injectors for optimising the noise emission of gasoline partially premixed combustion in a 2-stroke HSDI CI engine

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