Turbulent Mixing Losses in the Passages of Centrifugal Impellers

离心叶轮通道中的湍流混合损失

基本信息

批准号：
11650197
负责人：
MIYAMOTO Hiroyuki
金额：
$ 2.18万
依托单位：
Yatsushiro National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650197/
关键词：
Turbomachinery Blower Internal Flow Centrifugal Impeller Turbulent Flow Secondary Flow Blade Ti Leakage Hot-wire Measurement

项目摘要

Flow measurements were made within the passages of the shrouded and unshrouded centrifugal impellers, by using a hot-wire anemometer rotated with the same speed as that of the impeller. The measurements were made for a flow rate corresponding to nearly zero incidence angle and two other flows with reduced and increased flow rates.In the shrouded impeller, the measurements show that, as the flow rate is reduced, the regions of a low velocity and a dissipation enlarge from the shroud-side to the hub-side near the suction surface and the values of Reynolds normal stresses tend to decrease. The Reynolds shear stresses qualitatively follow the eddy viscosity concept. Near the suction surface, the effects of the flow rate on the shear stresses are remarkable in the cross-component between the passagewise and blade-spanwise directions, but are little in two other cross-components.In the unshrouded impeller, a low relative velocity, a high dissipation and a high Reynolds stress appear around t … More he region of the middle blade-to-blade to the casing side due to both influences of a blade tip leakage and a secondary flow. As the flow rate is reduced, this region enlarges by nearing the hub and also tends to move toward the suction.In the increased flow rate, the Reynolds stress is remarkably high near the casing of the suction side since the tip leakage noticeably influences there. In the reduced flow rate, the stress becomes high also on the suction because of the secondary flow strengthened near the casing. For three flow rates, however, the dissipation is remarkably high near the casing of the suction side ; the influence of the flow rate on the position with the highest dissipation seems to be little.Moreover, the numerical flow analys is made in the passage of the centrifugal impeller using FEM with/without the turbulence model. The turbulence model is low Reynolds k-ε model proposed by Chien. We use the Euler explicit method for the Reynolds averaged Navier-Stokes equations and the transport equations of the turbulent energy and the dissipation rate. All equations are discretized by the Galerkin method. The numerical results qualitatively correspond with those obtained from the experiment. Less

通过使用以与叶轮相同的速度旋转的热线风速计，在有盖和无盖离心叶轮的通道内进行流量测量。测量是针对与接近零入射角和另外两个相对应的流速进行的。在护罩叶轮中，测量表明，随着流速的降低，低速和耗散区域从护罩侧向叶轮侧扩大。靠近吸力面的轮毂侧，雷诺正应力值趋于减小，雷诺剪应力本质上遵循涡粘概念，在吸力面附近，流速对剪应力的影响是显着的。通道方向和叶片翼展方向之间的交叉分量，但在其他两个交叉分量中很小。在无罩叶轮中，在 t 周围出现低相对速度、高耗散和高雷诺应力。由于叶尖泄漏和二次流的双重影响，中间叶片到叶片的区域向壳体侧移动，随着流量的减小，该区域随着靠近轮毂而扩大，并且也趋向于向吸入口移动。流量增加时，由于叶尖泄漏的影响显着，因此吸入侧壳体附近的雷诺应力显着升高。流量减少时，由于吸入侧附近的二次流增强，因此吸入侧的应力也变高。套管。但对于三种流量，在吸力侧壳体附近的耗散量明显较高；流量对耗散量最高的位置的影响似乎很小。使用有限元法（有/无湍流模型）的离心叶轮湍流模型是 Chien 提出的低雷诺 k-ε 模型，我们使用欧拉显式方法进行雷诺平均。纳维-斯托克斯方程以及湍流能量和耗散率的输运方程所有方程均采用伽辽金法进行离散化，数值结果与实验结果定性一致。