考虑运行环境影响的燃气轮机涡轮叶片辐射测温方法研究

发布时间：2018-09-05 10:04

【摘要】：准确测量涡轮叶片温度,对保证燃气轮机安全运行具有重要意义。涡轮叶片温度测量一般采用辐射测温法,而叶片周围高温燃气的辐射与吸收,高温背景辐射反射会影响辐射测温精度。本课题针对这两个工作环境影响因素进行研究,提高涡轮叶片在线测温精度,最终提出考虑运行环境影响的涡轮叶片辐射测温方法。涡轮叶片周围的高温燃气自身会产生辐射,也会吸收叶片的辐射量。设计辐射高温计时通常选择避开气体辐射光谱,但是随着多光谱测温技术的发展以及光学器件的限制,难以选择完全不受影响的测量光谱。本文通过研究混合气体在高温高压条件下的辐射特点,分析不同工况下燃气辐射与吸收特性的变化,使用k分布模型将剧烈变化的光谱吸收系数重新排列成平滑单调上升的函数,并结合HITEMP数据库提出了光谱窗计算方法。与已有气体辐射计算方法相比,该方法的计算精度和计算速度均有优势,可对叶片测温时燃气的影响加以修正,并为测量光谱优化选择提供依据。工作环境的高温背景辐射在涡轮叶片表面所形成的反射量会直接影响测温结果。针对该问题,本文提出了一种高温背景下辐射温度计算方法。该方法中使用角系数描述反射量,建立反射影响下的辐射测温数学模型,进而降低其对测温结果造成的影响。辐射测温数学模型加入反射量后,难以对模型直接求解,本文在多光谱测温理论基础之上,结合改进后的多目标遗传算法对模型进行求解,提高了搜索效率和计算精度。通过对处于高温背景下目标的辐射测温实验,证明了所提出的方法可有效降低反射对测温精度的影响。涡轮叶片工作环境复杂,叶片在旋转到不同位置时所受到的反射影响不同,难以直接获取反射量。本文建立了涡轮叶片的背景辐射反射模型,用以准确描述叶片工作时反射量对测温精度的影响。在建模过程中,采用高次多项式拟合的方法替代叶片设计参数进而构造叶片型线方程,可在保证计算精度的前提下简化计算过程。同时,使用曲线网格结合面元化方法分析邻近热端部件的反射量,该方法与简化模型相比,充分考虑了叶片表面的非规则结构,并准确描述了工作环境反射量变化规律。通过半实物仿真实验,验证了反射模型具有较高的计算精度。在上述研究工作基础上,提出了考虑运行环境影响的燃气轮机涡轮叶片辐射测温方法。该方法对已有辐射测温数据处理方法加以改进,在数据处理过程中加入高温燃气辐射特性以及高温背景辐射反射影响计算,降低测温过程中涡轮叶片运行环境的影响,提高测温精度。最后,分析了涡轮叶片辐射测温数据处理过程中测温系统以及工作环境引入的测量不确定度。
[Abstract]:Accurate measurement of turbine blade temperature is of great significance to ensure the safe operation of gas turbine. The radiometric temperature measurement method is generally used for turbine blade temperature measurement, and the radiation and absorption of high temperature gas around the blade, the reflection of high temperature background radiation will affect the accuracy of radiation temperature measurement. In order to improve the accuracy of on-line temperature measurement of turbine blades, a method of radiation temperature measurement for turbine blades considering the influence of operating environment is put forward in this paper. The high temperature gas around the turbine blade produces radiation itself and absorbs radiation from the blade. The design of radiation high temperature timing usually avoids the gas radiation spectrum, but with the development of multispectral temperature measurement technology and the limitation of optical devices, it is difficult to choose the measurement spectrum which is completely unaffected. In this paper, the radiation characteristics of mixed gas under high temperature and high pressure are studied, and the change of gas radiation and absorption characteristics under different working conditions is analyzed. The K distribution model is used to rearrange the sharply varying spectral absorption coefficient into a function of smooth monotone rise and a spectral window calculation method is proposed based on the HITEMP database. Compared with the existing gas radiation calculation method, this method has advantages in calculation accuracy and speed, which can correct the influence of gas on the blade temperature measurement and provide the basis for the optimum selection of measurement spectrum. The reflection of the high temperature background radiation on the turbine blade surface will directly affect the temperature measurement results. In order to solve this problem, a method for calculating radiation temperature in high temperature background is presented in this paper. In this method, the angle coefficient is used to describe the reflectance, and the mathematical model of radiation temperature measurement under the influence of reflection is established to reduce its influence on the temperature measurement results. It is difficult to solve the model directly after adding reflectance to the mathematical model of radiation temperature measurement. Based on the theory of multi-spectral temperature measurement and the improved multi-objective genetic algorithm, the model is solved in this paper, which improves the search efficiency and the calculation accuracy. It is proved that the proposed method can effectively reduce the effect of reflection on the accuracy of temperature measurement through the experiment of radiation temperature measurement of the target in the high temperature background. Because of the complexity of turbine blade working environment, the blade is affected by different reflection when rotating to different position, so it is difficult to directly obtain the reflectance. In this paper, the background radiation reflection model of turbine blade is established to accurately describe the effect of blade reflectance on the accuracy of temperature measurement. In the process of modeling, the method of high order polynomial fitting is used to replace the blade design parameters and construct the blade profile equation, which can simplify the calculation process on the premise of ensuring the calculation accuracy. At the same time, the curved grid combined with surface element method is used to analyze the reflectance of adjacent hot end parts. Compared with the simplified model, the irregular structure of the blade surface is fully considered, and the variation law of the reflectance in the working environment is accurately described. The high accuracy of the reflection model is verified by the hardware-in-the-loop simulation experiment. On the basis of the above research work, a method for measuring the radiation temperature of gas turbine blade considering the influence of operating environment is put forward. This method improves the existing data processing method of radiation temperature measurement, and adds the radiation characteristics of high temperature gas and the calculation of reflection effect of background radiation in the process of data processing, so as to reduce the influence of turbine blade operating environment in the process of temperature measurement. Improve the accuracy of temperature measurement. Finally, the uncertainty of measurement system and working environment in the process of data processing of turbine blade radiation temperature measurement is analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TK477

【相似文献】