兩級葉盤轉子之模型驗證與結構強度分析

Model Validation and Structural Strength Analysis for a Dual-Stage Bladed Rotor

許全興(Hsu Chuan-Hsing)

指導教授 ： 林章生

國立屏東科技大學/工學院/車輛工程系所/碩士(2021年)

https://doi.org/10.6346/NPUST202100347

摘要

本研究利用有限元素法，探討頂壓回收渦輪機 (TRT) 系統之兩級葉盤，轉子結構在額定轉速下的氣動力和離心力影響，以及最大應力的發生位置；並藉由坎貝爾圖和SAFE圖分析兩級葉盤在轉子運行期間的動態特性。為了確保有限元素模型的可靠性，吾人以有限元素法對系統進行模態分析，藉此得到兩級葉盤的模態振型以及對應之自然頻率；並以實驗模態分析法獲取實際結構的模態參數，利用模態保證指標驗證模態振型的相關性，藉此確認實際結構與有限元素模型的一致性。本研究亦探討當TRT轉子運作時，由高爐頂壓推動動葉片所衍生的離心力與週期性氣動力作用下的應力分佈。最後，本文引用坎貝爾圖及SAFE圖搭配實驗模態分析量測之模態參數，評估葉片結構強度和耐久性。

關鍵字

渦輪機葉片 ； 離心力分析 ； 實驗模態分析 ； 模態保證指標 ； 坎貝爾圖 ； SAFE圖

並列摘要

In this study, we investigate the aerodynamic force, centrifugal force, and maximum stress on the structure of the dual-stage bladed rotor in Top-pressure Recovery Turbine (TRT) system under rated working conditions and the positions of occurrence using the Finite Element Method (FEM), as well as discuss the dynamic characteristics of bladed disks during the dual-stage bladed rotor operation through Campbell and SAFE diagrams. To confirm the effectiveness of the finite element models, the mode shapes and natural frequencies in the FEM-based modal analysis of the the dual-stage bladed rotor will be extracted, and compared with those of the practical structures through the Experimental Modal Analysis (EMA). To verify the agreement between the mode shapes of the finite element analysis and those of the actual structure, the Modal Assurance Criterion (MAC) is introduced here to confirm the reliability of the finite element model. The dual-stage bladed rotor is driven as the blast furnace top pressure pushes the moving blade; when the rotor rotates, the moving blade bears centrifugal and periodic aerodynamic forces. The stress distribution is investigated on the structure when these forces act simultaneously using aerodynamic analysis. To discuss whether the bladed disks will resonate with the external force under operation conditions, Campbell and SAFE diagrams containing the information of modal parameters obtained from EMA are employed to assess the strength and durability of the blades.

並列關鍵字

turbine blades ； centrifugal force analysis ； experimental modal analysis ； modal assmrance criterion ； Campbell diagram ； SAFE diagram

參考文獻

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