不同出口安装角扩压器内流动及级性能研究
发布时间：2018-11-08 17:20
【摘要】：离心压缩机广泛应用于冶金、化工、气体工业、机械等各个领域,因此在国民经济发展中占有非常重要的位置。扩压器作为离心压缩机中的核心静止部件,对提高压缩机级压比和效率,改善最佳工况点有着十分显著作用,因此研究不同出口安装角叶片扩压器的流动特性对离心压缩机的运行有着重要的意义。本文以某一台多级离心压缩机首级作为研究对象,对带不同出口安装角扩压器的离心压缩机级进行数值模拟,得出不同出口安装角情况下离心缩机单级的性能曲线,分析各扩压器不同叶高截面的流线和静压分布、不同等半径截面的总压得出扩压器出口安装角对扩压器内部流动的影响以及损失机理,同时采用压力恢复系数对比分析不同工况下不同扩压器的扩压效果;首次提出扩压器内的速度畸变指数概念进而分析各扩压器流道内气流的不均匀性,同时确定发生分离损失时的速度畸变指数临界值;对比分析扩压器内具有代表性位置的跨盘盖(轴向)绝对马赫数的分布。结果表明:随着扩压器出口安装角增大时,级性能曲线向大流量区移动,虽最高效率和压比先升高后降低,但对它们的提升并不明显且运行的最大工况变化不大;不同出口角度叶片扩压器的扩压效果由在不同工况下的流动特性决定;当扩压器进口安装角不变时,小流量时随着扩压器出口安装角增大,出口安装角大的扩压器最先出现分离并形成涡流区,涡流区从叶腹出口处发展到叶腹前缘,叶腹出现的旋涡对总压损失影响较小;大流量时,不同出口角度扩压器叶背形成分离区且旋涡位置不同,涡流区从叶背前缘发展到叶背出口处,叶背出现的旋涡对总压损失影响较大;同一扩压器在不同叶高截面的静压和流动情况也存在差异,叶片扩压器盖侧流动情况比盘侧好;速度畸变指数低于0.8时,扩压器发生分离损失;扩压器的出口安装角对扩压器入口处流动无明显影响。
[Abstract]:Centrifugal compressor is widely used in metallurgy, chemical industry, gas industry, machinery and other fields, so it occupies a very important position in the development of national economy. As the core static component of centrifugal compressor, diffuser plays a significant role in improving the compressor stage pressure ratio and efficiency, and improving the optimum working point. Therefore, it is of great significance to study the flow characteristics of blade diffuser with different outlet angles for the operation of centrifugal compressor. Taking the first stage of a multistage centrifugal compressor as the research object, the centrifugal compressor stage with different outlet angle diffuser is numerically simulated, and the single stage performance curve of centrifugal shrinkage machine is obtained under different outlet installation angles. By analyzing the flow line and static pressure distribution of different blade height sections of diffusers, and the total pressure of different radius sections, the influence of outlet mounting angle on the internal flow of diffusers and the loss mechanism are obtained. At the same time, the pressure recovery coefficient is used to analyze the diffuser's diffuser effect under different working conditions. The concept of velocity distortion index in diffuser is put forward for the first time, and the inhomogeneity of airflow in each diffuser channel is analyzed, and the critical value of velocity distortion exponent when separation loss occurs is determined. The distribution of absolute Mach number of cross-disc cover (axial) in representative position of diffuser is compared and analyzed. The results show that with the increase of the outlet mounting angle of diffuser, the stage performance curve moves to the large flow zone, although the maximum efficiency and the pressure ratio first increase and then decrease, but the lifting of them is not obvious and the maximum operating condition change is not obvious. The diffuser effect of blade diffuser with different outlet angle is determined by the flow characteristics under different working conditions. When the installation angle of diffuser inlet is constant, when the installation angle of diffuser outlet increases with small flow rate, the diffuser with large outlet installation angle first appears separation and forms eddy current zone, the eddy current zone develops from the outlet of ventral lobe to the leading edge of ventral lobe. The vortex in the ventral lobe had little effect on the total pressure loss. When the flow rate is large, the separation zone is formed at the back of the diffuser with different outlet angles and the vortex position is different. The vortex zone develops from the front edge of the back of the leaf to the outlet of the back of the leaf, and the vortex in the back of the leaf has a great influence on the total pressure loss. The static pressure and flow of the same diffuser at different blade height sections are different, the flow situation of the cover side of the blade diffuser is better than that of the disk side, and when the velocity distortion index is lower than 0.8, the diffuser loses separately. The outlet mounting angle of diffuser has no obvious effect on the inlet flow of diffuser.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH452
本文编号：2319168
[Abstract]:Centrifugal compressor is widely used in metallurgy, chemical industry, gas industry, machinery and other fields, so it occupies a very important position in the development of national economy. As the core static component of centrifugal compressor, diffuser plays a significant role in improving the compressor stage pressure ratio and efficiency, and improving the optimum working point. Therefore, it is of great significance to study the flow characteristics of blade diffuser with different outlet angles for the operation of centrifugal compressor. Taking the first stage of a multistage centrifugal compressor as the research object, the centrifugal compressor stage with different outlet angle diffuser is numerically simulated, and the single stage performance curve of centrifugal shrinkage machine is obtained under different outlet installation angles. By analyzing the flow line and static pressure distribution of different blade height sections of diffusers, and the total pressure of different radius sections, the influence of outlet mounting angle on the internal flow of diffusers and the loss mechanism are obtained. At the same time, the pressure recovery coefficient is used to analyze the diffuser's diffuser effect under different working conditions. The concept of velocity distortion index in diffuser is put forward for the first time, and the inhomogeneity of airflow in each diffuser channel is analyzed, and the critical value of velocity distortion exponent when separation loss occurs is determined. The distribution of absolute Mach number of cross-disc cover (axial) in representative position of diffuser is compared and analyzed. The results show that with the increase of the outlet mounting angle of diffuser, the stage performance curve moves to the large flow zone, although the maximum efficiency and the pressure ratio first increase and then decrease, but the lifting of them is not obvious and the maximum operating condition change is not obvious. The diffuser effect of blade diffuser with different outlet angle is determined by the flow characteristics under different working conditions. When the installation angle of diffuser inlet is constant, when the installation angle of diffuser outlet increases with small flow rate, the diffuser with large outlet installation angle first appears separation and forms eddy current zone, the eddy current zone develops from the outlet of ventral lobe to the leading edge of ventral lobe. The vortex in the ventral lobe had little effect on the total pressure loss. When the flow rate is large, the separation zone is formed at the back of the diffuser with different outlet angles and the vortex position is different. The vortex zone develops from the front edge of the back of the leaf to the outlet of the back of the leaf, and the vortex in the back of the leaf has a great influence on the total pressure loss. The static pressure and flow of the same diffuser at different blade height sections are different, the flow situation of the cover side of the blade diffuser is better than that of the disk side, and when the velocity distortion index is lower than 0.8, the diffuser loses separately. The outlet mounting angle of diffuser has no obvious effect on the inlet flow of diffuser.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH452
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