高负荷氦气压气机设计与改进研究

发布时间：2018-08-28 06:19

【摘要】：近年来,国际上提出了“第四代先进核能系统”的概念,这种核能系统具有良好的固有安全性,在经济上能够和其它发电方式竞争,并具有建设期短等优点。高温气冷堆是最有希望成为第四代先进核能系统的技术之一。高温气冷堆氦气轮机是高温堆的关键设备,而氦气压气机的气动设计是难点之一本文以日本300MW高温堆中的氦气压气机总体参数为目标,应用CFD软件进行数值模拟开发氦气扩压叶栅,研究氦气压气机气动设计特点和气体动力学方面的基本特性。分析氦气压气机重要设计参数的选取,并通过厚度分布叠加于中弧线,二次多项式控制中弧线折转规律,四次多项式控制厚度分布规律,四次多项式控制最大厚度位置得到初始叶型。三维数值模拟结果显示该叶型设计方案可以达到所需的气动设计目标。针对氦气压气机单级压比小、级数多的特点,研究高负荷设计方案。采用大流量系数、大载荷系数、高反动度措施,数值模拟分析该高负荷氦气叶栅的气动性能和流场特点。针对高负荷带来的严重三维分离特点,采取了中弧线最大弯度位置控制、调整动叶负荷径向分布、改变径向相对厚度重新积叠、定制根部顶部叶型、静叶弯曲设计等三维叶型改进和三维叶型设计技术,达到了抑制角区分离流动、减弱通道涡强度和尺寸、减小顶部间隙损失的目的,提高叶栅内流动性能,使得单级压比由1.03提高至1.05,级数减少了6级,并在设计转速全工况下,保证了高效率和宽的稳定工作范围。针对氦气的特殊性对某新型速度三角形进行研究,探讨其应用特点,并采用数值模拟手段将该速度三角形应用于氦气压气机三维叶栅中,达到进一步增加压比的目的。研究反动度的选取对氦气压气机叶栅气动性能的影响,结果表明负荷越大,采用高反动度的优势越明显。为了进一步接近设计目标,改变动叶负荷径向分布,减少积聚于根部的低能流体；研究新型叶栅厚度对气动性能的影响,结果表明,叶片减薄可以实现更好的扩压,提高叶栅流动性能。新型速度三角形可以成功实现氦气压气机高负荷目的,单级压比增至1.08,级数减至6级。对比分析压比和效率曲线,表明该新型高负荷设计在设计转速下保证高效率和足够的喘振裕度。
[Abstract]:In recent years, the concept of "the fourth generation advanced nuclear energy system" has been put forward internationally. This nuclear energy system has the advantages of good inherent safety, economic competition with other power generation modes, and short construction period. High temperature gas-cooled reactor is one of the most promising technologies for the fourth generation advanced nuclear power system. Helium turbine is the key equipment of high temperature gas cooled reactor (HTGR), and the aerodynamic design of Helium compressor is one of the difficulties in this paper, the overall parameters of helium compressor in 300MW high temperature reactor in Japan are taken as the target. The helium diffuser cascade was developed by numerical simulation with CFD software. The aerodynamic design characteristics of helium compressor and the basic characteristics of gas dynamics were studied. The selection of important design parameters of helium compressor is analyzed. The thickness distribution of helium compressor is superimposed on the middle arc, the curve is converted in the quadratic polynomial control, and the thickness distribution is controlled by the fourth order polynomial. The initial blade profile is obtained by controlling the maximum thickness position of the quartic polynomial. Three-dimensional numerical simulation results show that the blade profile design scheme can achieve the desired aerodynamic design objectives. Aiming at the characteristics of low single stage pressure ratio and many series of helium compressor, the design scheme of high load is studied. The aerodynamic performance and flow field characteristics of the high load helium cascade are numerically simulated by means of large flow coefficient, large load coefficient and high reaction degree. In view of the serious three dimensional separation characteristics brought by high load, the position control of maximum curvature of middle arc line is adopted, the radial distribution of moving blade load is adjusted, the relative thickness of radial blade is restacked, and the top blade shape of root is customized. Three dimensional blade shape improvement and three dimensional blade shape design technology, such as static blade bending design, can restrain the separation flow in angular region, weaken the intensity and size of channel vortex, reduce the loss of top clearance, and improve the flow performance in the cascade. The single-stage pressure ratio is increased from 1.03 to 1.05, and the series is reduced by six stages, and the high efficiency and wide stable working range are ensured under the whole operating condition of the design speed. According to the particularity of helium, a new type of velocity triangle is studied, and its application characteristics are discussed. The velocity triangle is applied to the three-dimensional cascade of helium compressor by numerical simulation to further increase the pressure ratio. The influence of reaction degree on the aerodynamic performance of helium compressor cascade is studied. The results show that the higher the load, the more obvious the advantage of high reaction degree. In order to get closer to the design goal, change the radial distribution of the moving blade load, reduce the low energy fluid accumulated at the root, the effect of the new cascade thickness on the aerodynamic performance is studied. The results show that the blade thinning can achieve better diffusing. Improved cascade fluidity. The new type of velocity triangle can successfully achieve the purpose of high load of helium compressor. The single-stage pressure ratio is increased to 1.08, and the series is reduced to 6 stage. By comparing the pressure ratio with the efficiency curve, it is shown that the new high load design ensures high efficiency and sufficient surge margin at the design speed.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH45

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