本文選題：熱障涂層 + 流固耦合�。� 參考：《湘潭大學(xué)》2015年碩士論文

【摘要】：熱障涂層因其良好的高溫隔熱效果而廣泛應(yīng)用于航空發(fā)動(dòng)機(jī)渦輪葉片,但是涂層在服役過程中的剝離失效嚴(yán)重制約了航空發(fā)動(dòng)機(jī)的使用壽命。因此,認(rèn)識(shí)熱障涂層的破壞失效機(jī)理對(duì)于提高葉片使用壽命尤為重要。高溫環(huán)境與應(yīng)力集中是涂層內(nèi)裂紋萌生和擴(kuò)展的根本原因。本文采用流固耦合的方法計(jì)算得到熱障涂層渦輪葉片服役過程中溫度和應(yīng)力分布,主要研究?jī)?nèi)容和結(jié)果如下:(1)本文建立了熱障涂層渦輪葉片流固耦合理論模型,流體域湍流核心區(qū)解時(shí)均化的N-S方程,壁面邊界層不直接求解微分方程而是用半經(jīng)驗(yàn)公式模擬近壁區(qū)溫度、速度等物理變量。固體域采用共軛熱傳導(dǎo)理論求解溫度場(chǎng),將溫度場(chǎng)作為預(yù)定義場(chǎng)變量,利用熱彈塑性理論求解固體域應(yīng)力場(chǎng)。耦合邊界處溫度和熱流連續(xù)。(2)本文實(shí)現(xiàn)了熱障涂層流固耦合的數(shù)值模擬過程,流體模型和固體模型分別采用FLUENT軟件和ABAQUS軟件單獨(dú)進(jìn)行計(jì)算,耦合界面通過MPCCI實(shí)現(xiàn)溫度和對(duì)流換熱系數(shù)等物理變量的數(shù)據(jù)傳遞。ABAQUS軟件中利用布爾相減和布爾相加技術(shù)建立多層復(fù)雜幾何結(jié)構(gòu)的二維熱障涂層幾何模型,網(wǎng)格劃分過程中,靠近氧化層附近區(qū)域采用四邊形為主、三角形為輔的網(wǎng)格策略,給定位移和熱邊界,建立固體域計(jì)算模型。本文流體域采用ICEM CFD軟件進(jìn)行結(jié)構(gòu)化網(wǎng)格劃分,考慮邊界層物理變量梯度效應(yīng),加密邊界層附近網(wǎng)格密度。為了實(shí)現(xiàn)流體和固體之間的共軛熱傳導(dǎo),固體域傳遞壁面溫度到流體模型,反過來流體域傳遞膜溫度和對(duì)流換熱系數(shù)到固體域,當(dāng)固體域和流體域計(jì)算收斂后,計(jì)算結(jié)束。(3)本文計(jì)算得到了二維熱障涂層渦輪葉片服役過程中的溫度和應(yīng)力分布:穩(wěn)態(tài)條件下,陶瓷層表面前緣和尾緣處溫度相對(duì)較高,溫度最大值為1035°C,位于葉片前緣處,吸力面溫度整體低于壓力面溫度。另外,鑭系氧化物面層(LCO)有一定的隔熱效果,可以使金屬基底溫度下降20°C左右。發(fā)動(dòng)機(jī)穩(wěn)定工作階段,葉片氧化層環(huán)向應(yīng)力值分布在1.12GPa~3.75 GPa之間,吸力面和壓力面氧化層內(nèi)應(yīng)力水平高,容易引起裂紋的萌生與擴(kuò)展;葉片冷卻后,氧化層內(nèi)環(huán)向殘余應(yīng)力值分布在250 MPa~-3.5 GPa之間,前緣和尾緣附近殘余應(yīng)力水平高,容易引起應(yīng)力集中�？傊�,本文采用流固耦合分析方法實(shí)現(xiàn)了二維熱障涂層渦輪葉片瞬態(tài)溫度場(chǎng)和應(yīng)力場(chǎng)的數(shù)值模擬,得到各個(gè)時(shí)間段熱障涂層渦輪葉片溫度和熱應(yīng)力的分布,對(duì)葉片服役過程中可能出現(xiàn)的失效位置做了初步的預(yù)測(cè),為熱障涂層的研究提供了一種新的思路。
[Abstract]:Thermal barrier coatings are widely used in aero-engine turbine blades due to their good thermal insulation effect. However, the service life of aero-engine is seriously restricted by the peeling failure of the coatings in service. Therefore, it is very important to understand the failure mechanism of thermal barrier coating for increasing the service life of blade. High temperature environment and stress concentration are the root causes of crack initiation and propagation. In this paper, the temperature and stress distribution of thermal barrier coating turbine blade during service is calculated by using fluid-solid coupling method. The main contents and results are as follows: (1) the theoretical model of fluid-solid coupling of thermal barrier coating turbine blade is established in this paper. The homogeneous N-S equation in turbulent core region in fluid domain is not directly solved by the wall boundary layer, but by semi-empirical formula to simulate the physical variables such as temperature and velocity near the wall. The conjugate heat conduction theory is used to solve the temperature field and the temperature field is taken as the predefined field variable. The thermoelastic-plastic theory is used to solve the stress field in the solid domain. The coupled boundary temperature and heat flux are continuous. (2) the numerical simulation process of fluid-solid coupling of thermal barrier coating is realized. The fluid model and solid model are calculated separately by fluent and Abaqus software. The coupled interface realizes the data transfer of physical variables such as temperature and convection heat transfer coefficient by MPCCI. In Abaqus software, using Boolean subtraction and Boolean addition techniques, a two-dimensional thermal barrier coating geometric model with multilayer and complex geometry structure is established. The meshing strategy of quadrilateral and triangle is used in the area near the oxide layer. The calculation model of solid domain is established based on the given displacement and thermal boundary. In this paper, ICEM CFD software is used for structured mesh generation in the fluid domain. Considering the gradient effect of physical variables in the boundary layer, the density of the grid near the boundary layer is encrypted. In order to realize the conjugate heat conduction between fluid and solid, the solid domain transfers wall temperature to the fluid model, in turn, the fluid domain transfer membrane temperature and convection heat transfer coefficient to the solid domain, when the calculation in the solid and fluid domains converges, (3) in this paper, the temperature and stress distribution of two-dimensional thermal barrier coated turbine blade are calculated. Under steady state condition, the temperature at the front edge and tail edge of ceramic layer is relatively high, and the maximum temperature is 1035 擄C, which is located at the front edge of the blade. Suction surface temperature is lower than pressure surface temperature. In addition, the lanthanide oxide surface layer (LCO) has a certain thermal insulation effect, which can reduce the metal substrate temperature by about 20 擄C. In the stable working stage of the engine, the circumferential stress of the oxidation layer of the blade is between 1.12 GPA and 3.75 GPA, and the stress level of the oxidation layer on the suction and pressure surfaces is high, which can easily lead to the initiation and propagation of cracks, and when the blade is cooled, The internal circumferential residual stress of the oxide layer is distributed between 250 MPA and 3.5 GPA, and the residual stress level near the front edge and the tail edge is high, which can easily lead to stress concentration. In a word, the numerical simulation of transient temperature field and stress field of two dimensional thermal barrier coating turbine blade is realized by using fluid-solid coupling analysis method, and the distribution of temperature and thermal stress of thermal barrier coating turbine blade is obtained in every time period. The failure locations of the blades during service are preliminarily predicted, which provides a new idea for the study of thermal barrier coatings.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：V263

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 牟仁德;陸峰;何利民;賀世美;黃光宏;;熱障涂層技術(shù)在航空發(fā)動(dòng)機(jī)上的應(yīng)用與發(fā)展[J];熱噴涂技術(shù);2009年01期

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本文編號(hào)：2055351