Mixed convective characteristics of the combustion of a nanoparticles-laden fuel (n-butanol nanofluid) in a vented cavity are investigated. The nanofluid and the oxidizer enter the cavity through the inlets on the left and right vertical walls, respectively. However, the resulting product produced from the oxidation process of the fuel exits the cavity through the outlet at the bottom wall. Heat generated from the oxidation process causes natural convection within the cavity. The conjugate effect of natural and forced convection finally gives rise to mixed convection phenomena. In this regard, a mathematical model for mixed convection flow in a vented cavity is formulated with no-slip and isothermal boundary conditions. Having transformed the model into a dimensionless form, the stream function-vorticity formulation is used. The resulting equations are then solved numerically using the finite difference method. Numerical results are illustrated with the streamlines, isotherms, and isolines of fuel and oxidizer concentrations. The maximum values of the stream function (ψmax) and the temperature (θmax) are found to increase with an increase in the Frank–Kamenetskii number (Λ), volume fraction of nanoparticles (φ), and stoichiometric ratio (χ). On the contrary, they decrease with the increase in the Reynolds number (Re). When the Grashof number (Gr) is increased, ψmax increases and θmax decreases. The remaining concentrations of fuel, (CF)min, and oxidizer, (CO)min, are higher for an increase in Gr, whereas the opposite is recognized for increasing Λ. With the increase in Gr and Λ, the steady-state flow in the cavity tends to be oscillating and then chaotic.

中文翻译：

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充满纳米粒子的化学物质在通风腔中的燃烧

研究了充满纳米颗粒的燃料（正丁醇纳米流体）在通风腔中燃烧的混合对流特性。纳米流体和氧化剂分别通过左侧和右侧垂直壁上的入口进入腔体。然而，燃料氧化过程产生的最终产物通过底壁处的出口离开腔体。氧化过程产生的热量导致腔内自然对流。自然对流和强制对流的共轭作用最终产生混合对流现象。在这方面，在无滑移和等温边界条件下制定了通风腔中混合对流的数学模型。将模型转换为无量纲形式后，使用流函数-涡度公式。然后使用有限差分法对所得方程进行数值求解。数值结果用流线、等温线以及燃料和氧化剂浓度等值线来说明。发现流函数 (ψmax) 和温度 (θmax) 的最大值随着 Frank-Kamenetskii 数 (Λ)、纳米粒子体积分数 (φ) 和化学计量比 (χ) 的增加而增加。相反，它们随着雷诺数（Re）的增加而减少。当格拉霍夫数 (Gr) 增大时，ψmax 增大，θmax 减小。 Gr 增加时，剩余燃料浓度 (CF)min 和氧化剂 (CO)min 较高，而随着 Λ 增加，则相反。随着Gr和Λ的增大，腔内稳态流动趋于振荡，进而趋于混沌。