Lu Maoqi, Fu Zhongguang, Yuan Xinkun, Wu Jiayao, Sabir Syed Waqas
School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China.
ACS Omega. 2021 Mar 3;6(10):6629-6642. doi: 10.1021/acsomega.0c05418. eCollection 2021 Mar 16.
The C = 1.6 standard - ε equation combined with the steady flamelet model was applied to a methane/dimethyl ether swirl combustion field, and the effects of the dimethyl ether (DME) blending ratio and operating pressure on the flame behavior, including species variation, reaction zone behavior, and flame entrainment, were investigated. The results demonstrated that selected models could better reproduce the trends of the experimental measurements. The downstream reaction zone achieved better calculation accuracy than the outer shear layer of the first recirculation zone. The addition of DME accelerated the accumulation process of H, O, H, and OH radicals. The intermediate radical CHO was rapidly developed by the influence of the H extraction rate under a constant fuel volume flow rate. The reaction zone dimensions were approximately linearly and positively correlated with the DME blending ratio, whereas flame entrainment expressed a lower DME concentration dependence in the high-DME mass-dominated system. The operating pressure significantly impacted the distribution of reactive radicals in the turbulent flame; meanwhile, the flame and reaction zone length showed nonlinear inverse behavior with pressure variation, while the thickness of the reaction zone was always linearly and negatively correlated with pressure. Moreover, the peak flame entrainment rate also experienced a nonlinear decline with pressure elevation; however, the peak positions were not sensitive to pressure fluctuation. Concurrently, the response surface functions for the reaction zone dimensions were established covering the range of 0-1 for the DME blending ratio and 1-5 atm operating pressure, which could provide assistance for combustion condition optimization and combustion chamber design.
将C = 1.6标准 - ε方程与稳态小火焰模型相结合，应用于甲烷/二甲醚旋流燃烧场，研究了二甲醚（DME）掺混比和运行压力对火焰行为的影响，包括物种变化、反应区行为和火焰卷吸。结果表明，所选模型能够更好地再现实验测量趋势。下游反应区的计算精度优于第一再循环区的外剪切层。添加二甲醚加速了H、O、H和OH自由基的积累过程。在恒定燃料体积流量下，中间自由基CHO受H提取率的影响迅速发展。反应区尺寸与二甲醚掺混比近似呈线性正相关，而在高二甲醚质量占主导的系统中，火焰卷吸对二甲醚浓度的依赖性较低。运行压力显著影响湍流火焰中活性自由基的分布；同时，火焰和反应区长度随压力变化呈非线性反比关系，而反应区厚度始终与压力呈线性负相关。此外，峰值火焰卷吸率也随压力升高呈非线性下降；然而，峰值位置对压力波动不敏感。同时，建立了反应区尺寸的响应面函数，涵盖二甲醚掺混比0 - 1和运行压力1 - 5 atm的范围，可为燃烧条件优化和燃烧室设计提供帮助。
