A Numerical Study on the Influence of Hole Depth on the Static and Dynamic Performance of Hole-Pattern Seals
A Numerical Study on the Influence of Hole Depth on the Static and Dynamic Performance of Hole-Pattern Seals
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DOI：
10.1115/1.4028604
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发表时间：
2015
影响因子：
2.5
通讯作者：
P. Migliorini;A. Untaroiu;H. Wood
中科院分区：
文献类型：
--
作者：
P. Migliorini;A. Untaroiu;H. Wood
环形密封件通过减少过程流体的泄漏同时还对转子系统产生潜在的不稳定力而在涡轮机的动力学中起到重要作用。孔型密封一直是许多研究的焦点，但最近的实验研究表明，仍然有许多现象需要探索。其中一种现象是孔深度对密封静态和动态特性的影响。本文采用计算流体动力学（CFD）/整体流混合方法研究了查尔兹等人在对孔型密封的实验测量中发现的孔深与泄漏量之间的非单调关系。（2014年，“孔深度对孔式定子气体环形密封的转子动力学和泄漏特性的影响”，ASME J. Eng. Gas Turbines Power，136（4），第042501页）。考虑三种孔深（1.905 mm、3.302 mm和6.604 mm）和三种运行速度（10，200 rpm、15，350 rpm和20，200 rpm）。对于稳态流动，采用k-ε湍流模型求解全密封几何形状的周向周期性扇区的三维雷诺平均纳维尔-斯托克斯（RANS）方程。将稳态结果输入到整体流模型的一阶方程中，以预测转子动力系数。的混合方法的结果进行比较，实验数据。对于3.302 mm和6.604 mm孔深配置，CFD预测的泄漏显示出良好的一致性（在5%以内）。对于1.905 mm孔深密封，一致性在17%以内。用剪切应力输运（SST）湍流模型进行的一组附加计算结果的一致性较差。对沿着密封件的流线进行的检查表明，孔深控制了孔中形成的涡流形状，从而驱动了间隙区域中射流所经受的阻力。对于转子动力系数，最激励频率的预测和实验之间显示出良好的一致性。
Annular seals serve an important role in the dynamics of turbomachinery by reducing leakage of a process fluid while also contributing potentially destabilizing forces to the rotor system. Hole-pattern seals have been the focus of many investigations, but recent experimental studies have shown that there are still many phenomena that require exploration. One such phenomenon is the influence of hole depth on the static and dynamic characteristics of the seal. In this paper, a hybrid computational fluid dynamics (CFD)/bulk-flow method is employed to investigate the nonmonotonic relationship between hole depth and leakage shown in experimental measurements of a hole-pattern seal by Childs et al. (2014, “The Impact of Hole Depth on the Rotordynamic and Leakage Characteristics of Hole-Pattern-Stator Gas Annular Seals,” ASME J. Eng. Gas Turbines Power,136(4), p. 042501). Three hole depths (1.905 mm, 3.302 mm, and 6.604 mm) and three running speeds (10,200 rpm, 15,350 rpm, and 20,200 rpm) are considered. For the steady-state flow, the 3D Reynolds-Averaged-Navier-Stokes (RANS) equations are solved with the k-ϵturbulence model for a circumferentially periodic sector of the full seal geometry. The steady-state results are input into the first-order equations of a bulk-flow model to predict rotordynamic coefficients. Results of the hybrid method are compared to experimental data. CFD predicted leakage showed good agreement (within 5%) for the 3.302 mm and 6.604 mm hole depth configurations. For the 1.905 mm hole depth seal, agreement was within 17%. An additional set of calculations performed with the shear stress transport (SST) turbulence model produced worse agreement. Examination of streamlines along the seal show that the hole depth controls the shape of the vortex that forms in the hole, driving the resistance experienced by the jet flow in the clearance region. For the rotordynamic coefficients, good agreement is shown between predictions and experiment for most excitation frequencies.