Combustion noise analysis of partially premixed combustion concept using gasoline fuel in a 2-stroke engine

Abstract

ElsevierBroatch Jacobi, JA.; Margot, X.; Novella Rosa, R.; Gómez-Soriano, J. (2016). Combustion noise analysis of partially premixed combustion concept using gasoline fuel in a 2-stroke engine. Energy. 107:612-624. AbstractIn the last decade, different advanced combustion concepts based on generating totally or partially premixed conditions have been investigated in CI engines with the aim of achieving lower NOx and soot emissions. Most of the drawbacks inherent to this type of combustions, such as the combustion phasing control or combustion stability, can be mitigated by combining the PPC concept fueled by gasoline and a small 2-stroke HSDI engine. However, combustion noise issue remains unsolved while it is a critical aspect due to its strong influence in the customer purchasing decision and compliance of more stringent regulations. In this work, an analysis of the combustion noise generated by PPC combustion concept is performed in order to identify the most influential parameters and to define key paths for controlling the noise level. In addition, 3D CFD simulations have been performed to further understand the combustion noise generation mechanisms. Results evidence how the strong impact of the maximum pressure time-derivative achieved during combustion process renders all other sources of noise generation irrelevant. The trade-off between combustion noise and combustion efficiency of this PPC concept has been confirmed, while the intrinsic relation between such parameters and the engine efficiency has been also evaluated.

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

“…It is around 0.8 dB for the baseline, whereas in a case of the optimized configuration, a 1.6 dB of difference is seen. As Broatch et al and Torregrosa et al emphasized in several previous studies [22,23,56], local thermodynamic conditions before ignition govern the combustion phenomena and its subsequent in-cylinder pressure field effects. Therefore, limiting the simulation to the closed cycle and initializing the simulation with the results of the previous gas exchange process using the baseline configuration, may affect the prediction of noise levels when the geometry is highly modified, since local thermodynamic conditions can change notably.…”

“…Traditional in-cylinder pressure measurements through a single transducer do not provide enough information for evaluating the effects of the resonance due to local fluctuations of the pressure field. Broatch et al [22] proposed a methodology based on CFD simulations to overcome this limitation without complex and expensive engine modifications. They compared the simulated and measured pressure profiles at the same location of the pressure transducer and checked the consistency between numerical results and measurements in both the time and frequency domains.…”

“…Examples of such validation can be found in Refs. [22,52]. Therefore, the CFD soot/NO x predictions are considered to be sufficiently representative of the real emission levels in this study.…”

“…In particular, the use of computational fluid dynamics (CFD) is nowadays widely established in the automotive industry. Moreover, recent studies have demonstrated that CFD is a useful tool to recreate, visualize and study the combustion noise source [22,23]. Despite the attractive benefits of this method, the simulation of an internal combustion engine is challenging due to complex geometry, spatially and temporally varying conditions and complicated combustion chemistry.…”

Thermo- and Fluid-Dynamic Processes in Direct Injection Engines: THIESEL 2016 Special Issue

“…[4][5][6][7] One main advantage of computational fluid dynamics (CFD) is that it becomes possible to identify not only the processes that lead to NO x and soot emissions but also those contributing to combustion noise levels. 8 At the same time, experimental studies are still very necessary to provide validation of these models and ensure adequate representation of the phenomena. 9,10 Hence, laser induced fluorescence-particle image velocimetry (LIF-PIV), high-speed ultraviolet (UV) chemiluminescence imaging and X-ray radiography techniques have to be adapted to obtain all relevant information.…”