本研究以具有聚丙烯材料配置之複合垂直平板模擬燃燒室外殼，探討其受內部熱源加熱後之暫態自然對流熱傳特性。研究方法結合實驗溫度量測、三維計算流體力學模擬與逆向分析，並利用最小平方法反推加熱過程中之有效熱源。數值模型以 ANSYS Fluent 建立，包含加熱片、聚丙烯、S45C 鋼材、陶瓷纖維板及外部空氣計算域。流動模型之選定則以均方根誤差、熱傳係數與最大速度作為判斷依據，比較不同模型於暫態自然對流過程中之適用性。
結果顯示，暫態加熱過程中之外部流場可分為層流區、過渡區及紊流區。加熱初期以Laminar模型較適用，過渡階段則以ZEM模型較能描述流場特性；當流場逐漸發展至後期時，RNG k-ε模型與熱傳及流速估算結果較為一致。此外，穩態分析結果顯示，垂直平板沿高度方向會呈現不同局部流場型態，且速度邊界層與熱邊界層厚度皆隨高度增加而改變。

This study investigates transient natural convection heat transfer from a composite vertical plate containing a polypropylene layer and subjected to an internal heat source. Experimental temperature measurements, three-dimensional computational fluid dynamics simulations, and an inverse analysis based on the least squares method are combined to estimate the effective heat generation rate and predict thermal and flow quantities that are difficult to measure directly. Four flow models - laminar, zero-equation (ZEM), standard k-ε, and RNG k-ε - are assessed using the root mean square error, heat transfer coefficient, and maximum velocity. The laminar model is appropriate before 400 s, ZEM is selected for the transitional period from 800 to 1200 s, and RNG k-ε provides the most consistent results after 2000 s and at steady state. A comparison between transient Rayleigh numbers and steady local Rayleigh numbers indicates laminar, transitional, and turbulent-development regions along the lower, middle, and upper portions of the plate, respectively. Both the thermal and velocity boundary layers grow with height, while the thermal boundary layer remains thicker for air with Pr ≈ 0.7. Piecewise height-corrected correlations are proposed for their thickness ratio.

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