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<p>This study investigates the combustion characteristics associated with three distinct piston geometries under 2000 RPM full-load conditions (fuel injection quantity: 62&#xa0;mg). To optimize engine performance, the compression ratio was fixed at 11.0 for all cases. Piston designs include a squish-maximized Type-C, a tumble-enhanced Type-B with minimized squish area, and a baseline Type-A configuration. Simulations were performed across two continuous cycles, with analysis conducted on the second cycle. Results reveal that Type-B achieved the most favorable performance, including the highest gross indicated mean effective pressure (IMEP) of 1.92&#xa0;MPa, the earliest combustion phasing (CA10 = 0.5° aTDC), and the shortest combustion duration of 23.0° CA. Type-B also recorded the highest peak heat release rate (381&#xa0;J/CA) and turbulence kinetic energy (29.8 m<sup>2</sup>/s<sup>2</sup>) near ignition, promoting rapid and stable flame propagation. In contrast, Type-C exhibited delayed combustion (CA10 = 4.5° aTDC), the longest duration (32.5° CA), and the lowest IMEP (1.81&#xa0;MPa), despite demonstrating improved knock resistance. The IMEP of Type-C was 6% lower than that of Type-B. These findings highlight the critical influence of piston crown design on in-cylinder flow development and hydrogen combustion performance.</p>

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Effect of the Piston Bowl Geometry on In-Cylinder Flow and Combustion in a Hydrogen Internal Combustion Engine: A CFD Study

  • 期刊论文

  • 发表日期：

    2025年9月22日

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  • Seongsu Kim,
  • Wookeun Choi,
  • Myungjik Bae,
  • Junghwan Kim

摘要

This study investigates the combustion characteristics associated with three distinct piston geometries under 2000 RPM full-load conditions (fuel injection quantity: 62 mg). To optimize engine performance, the compression ratio was fixed at 11.0 for all cases. Piston designs include a squish-maximized Type-C, a tumble-enhanced Type-B with minimized squish area, and a baseline Type-A configuration. Simulations were performed across two continuous cycles, with analysis conducted on the second cycle. Results reveal that Type-B achieved the most favorable performance, including the highest gross indicated mean effective pressure (IMEP) of 1.92 MPa, the earliest combustion phasing (CA10 = 0.5° aTDC), and the shortest combustion duration of 23.0° CA. Type-B also recorded the highest peak heat release rate (381 J/CA) and turbulence kinetic energy (29.8 m2/s2) near ignition, promoting rapid and stable flame propagation. In contrast, Type-C exhibited delayed combustion (CA10 = 4.5° aTDC), the longest duration (32.5° CA), and the lowest IMEP (1.81 MPa), despite demonstrating improved knock resistance. The IMEP of Type-C was 6% lower than that of Type-B. These findings highlight the critical influence of piston crown design on in-cylinder flow development and hydrogen combustion performance.