Abstract The present paper focuses on the optimization of the thermal performance for compressible laminar natural convection flow induced under high-temperature difference in an open-ended vertical channel by optimizing the channel inter-plate spacing using numerical simulation. The present investigation is conducted for a wide range of Rayleigh number (Ra) 10 4 to 10 7 in channel heated asymmetrically by uniform surface temperature with air ( P r 0.72 ) as working fluid. Several values of channel gap between plates, new modified preconditioned all-speed Roe scheme along with dual time stepping technique and modified Local One-dimensional Inviscid (LODI) relations as channel inlet and outlet boundary conditions suitable for compressible laminar natural convection is employed for the current simulation. Heat transfer rate in terms of average Nusselt number is obtained for all Rayleigh number and channel aspect ratio is obtained. Variation of thermal and velocity profiles, the variation of average Nusselt number and mass flow rate into the channel for the combination of each Rayleigh number and channel aspect ratio is reported. From the results obtained, a correlation for optimum aspect ratio with Rayleigh number which maximizes the heat transfer within the channel is presented.

中文翻译：

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开放式垂直通道可压缩层流自然对流热性能优化研究

摘要 本文通过数值模拟优化通道板间距，研究了开放端垂直通道在高温差下引起的可压缩层流自然对流热性能的优化。目前的研究是针对大范围的瑞利数 (Ra) 10 4 到 10 7 进行的，通道中通过均匀的表面温度不对称加热，空气 (P r 0.72) 作为工作流体。板间通道间隙的几个值、新的改进的预处理全速 Roe 方案以及双时间步长技术和改进的局部一维无粘性 (LODI) 关系作为适用于可压缩层流自然对流的通道入口和出口边界条件被用于当前模拟。获得所有瑞利数和通道纵横比的平均努塞尔数的传热率。报告了每个瑞利数和通道纵横比的组合的热和速度分布的变化、平均努塞尔数和进入通道的质量流量的变化。从获得的结果中，呈现了最佳纵横比与瑞利数的相关性，这使得通道内的热传递最大化。