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<p>This study presents a detailed numerical investigation of four cavity-based flameholder geometries wedge, wavy wall, triangular bump, and circular bump integrated into a Mach 2.5 ethylene-fuelled scramjet combustor. The simulations employ a density-based, finite-rate chemistry Reynolds-Averaged Navier–Stokes framework with the SST k–ω turbulence model to resolve the coupled effects of compressibility, shock–boundary layer interaction, and turbulent combustion. Inlet conditions replicate vitiated air–fuel operation, with ethylene selected for its high laminar flame speed, wide flammability limits, and short ignition delay under high-enthalpy conditions. Comparative analysis of velocity, temperature, H<sub>2</sub>O mass fraction, static pressure, Mach number distributions, and density gradients reveals that flameholder geometry critically governs shear-layer growth rate, vortex-induced entrainment, and recirculation zone strength parameters that dictate ignition distance, mixing rate, and peak heat release. The triangular bump exhibited the most aggressive mixing, achieving complete fuel–air homogenization and ignition within 45&#xa0;mm, with peak flame temperatures of 2850–2900&#xa0;K, but incurred the highest-pressure loss factor (0.77). The wavy wall provided a balanced performance, igniting within 50–55&#xa0;mm with moderate losses (0.68). The circular bump delayed ignition (60–65&#xa0;mm) yet preserved total pressure (0.70), while the wedge minimized losses (0.55) but required ~ 80–85&#xa0;mm for full ignition. These findings highlight the trade-off between rapid combustion completion and aerodynamic efficiency, offering design guidance for tailoring flameholder geometry to mission-specific scramjet performance requirements.</p>

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Shock–vortex–flame interaction and performance of innovative cavity flameholders in a Mach 2.5 ethylene-fuelled scramjet combustor

  • 期刊论文

  • 发表日期：

    2025年9月24日

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  • Shaik Shajahan,
  • S. K. Gugulothu,
  • Raju Muthyala,
  • Vudimudi Priyanka

摘要

This study presents a detailed numerical investigation of four cavity-based flameholder geometries wedge, wavy wall, triangular bump, and circular bump integrated into a Mach 2.5 ethylene-fuelled scramjet combustor. The simulations employ a density-based, finite-rate chemistry Reynolds-Averaged Navier–Stokes framework with the SST k–ω turbulence model to resolve the coupled effects of compressibility, shock–boundary layer interaction, and turbulent combustion. Inlet conditions replicate vitiated air–fuel operation, with ethylene selected for its high laminar flame speed, wide flammability limits, and short ignition delay under high-enthalpy conditions. Comparative analysis of velocity, temperature, H2O mass fraction, static pressure, Mach number distributions, and density gradients reveals that flameholder geometry critically governs shear-layer growth rate, vortex-induced entrainment, and recirculation zone strength parameters that dictate ignition distance, mixing rate, and peak heat release. The triangular bump exhibited the most aggressive mixing, achieving complete fuel–air homogenization and ignition within 45 mm, with peak flame temperatures of 2850–2900 K, but incurred the highest-pressure loss factor (0.77). The wavy wall provided a balanced performance, igniting within 50–55 mm with moderate losses (0.68). The circular bump delayed ignition (60–65 mm) yet preserved total pressure (0.70), while the wedge minimized losses (0.55) but required ~ 80–85 mm for full ignition. These findings highlight the trade-off between rapid combustion completion and aerodynamic efficiency, offering design guidance for tailoring flameholder geometry to mission-specific scramjet performance requirements.