1 edition of Rotordynamic effects driven by fluid forces from a geometrically imperfect labyrinth seal found in the catalog.
Rotordynamic effects driven by fluid forces from a geometrically imperfect labyrinth seal
William C. Williston
by Naval Postgraduate School, Available from National Technical Information Service in Monterey, Calif, Springfield, Va
Written in English
The forces on a rotor due to asymmetric pressure distributions resulting from a single gland non-circular labyrinth seal in a circular outer casing are analyzed for the purpose of understanding the possible causes of synchronous vibration due to seal intolerance. A lumped parameter model is developed for flow in the azimuthal direction inside the seal gland. The sealing knife imperfections causing the non-circularity may be due to manufacturing defects or in service ware. The resulting continuity and momentum equations are solved using a regular linear perturbation technique. Results from this model indicate under what conditions seal imperfections can generate forces of the same order of magnitude as rotor mass unbalance.
|Statement||William C. Williston, Jr|
|The Physical Object|
|Pagination||34 p. ;|
|Number of Pages||34|
Seal force is an important factor in turbomachineries. The paper puts forward an expanded seal force identification model. A seal test rig with many sets of seals was set up. The distributed seal force in the cylinder was equivalent to the two selected planes by using double-plane unbalance force identification theory in rotordynamics. To consider the complex vibration of cylinder with Author: Dan Sun, Yan Ting Ai, Wan Fu Zhang, Jian Gang Yang. A labyrinth seal is cross-sectioned in Fig. A. There is a rotating mechanical shaft seal “mech seal” located in the “head.” See Fig. The head of the seal will be bolted to the bottom of the pump intake. Well fluid moving into the pump intake will be on the top of this shaft seal.
An in-depth analysis of machine vibration in rotating machineryWhether it's a compressor on an offshore platform, a turbocharger in a truck or automobile, or a turbine in a jet airplane, rotating machinery is the driving force behind almost anything that produces or uses energy. threedimensional fluid flow inside the labyrinth seal of a turbomachine. Specific geometry elements of the labyrinth in triortogonal system and flow parameters on the labyrinth’s inlet and outlet are shown in Figure 2, inwhich we notedR – rotor, C ca–sing, ω -File Size: 1MB.
4 Labyrinth Seal Dynamics Coefficients Study Results for the labyrinth seal model of Fig 2 using Childs’ experimental conditions  are shown in Fig 8. The labyrinth seal geometric conditions are follows: Seal length is mm, seal diameter is mm and radial clearance is mm. The results are presented as dynamicFile Size: KB. Rotordynamic and leakage data are presented for a see-through tooth-on-rotor (TOR) labyrinth seal with comparisons to a see-through tooth-on-stator (TOS) labyrinth seal. Measurements for both seals are also compared to predictions from XLLaby. Both seals have identical diameters and can be considered as relatively long labyrinth by: 1.
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Effectsarecompatiblewiththemodalshapesselectedforbalancing. This thesiswill develop a model that predictstheforceresulting from the fluid effects inducedby anon-circularrotatinglabyrinth seal. Approved for public release; distribution is unlimitedThe forces on a rotor due to asymmetric pressure distributions resulting from a single gland non-circular labyrinth seal in a circular outer casing are analyzed for the purpose of understanding the possible causes of synchronous vibration due to seal : William C.
Williston. The radial force acting on a rotor, due to an asymmetric pressure distribution inside the seal gland, generated from a slightly non-circular single gland labyrinth seal rotating inside a circular outer casing is investigated : Knox T. Millsaps, William C.
Williston. [Show full abstract] labyrinth seal with a flat, stator mounted land. The impact of different flow coefficients for the first and second knives on the rotordynamic coefficients was found.
For all labyrinth seal designs, transient computational-fluid-dynamics solutions were carried out at the same operating condition: inlet pressure of bar, pressure ratio ofrotational.
The labyrinth seal of a large scales steam turbine is taken as an object of analysis and a 3D model with eccentric rotor is solved to obtain the rotordynamic force components. The rotordynamic force is derived by integrating the pressure on the rotor surface. Evaluation formula is formed from the results of numerical calculation, which is used Cited by: 4.
Fluid Flow Equations for Rotordynamic Flows in Seals and Leakage Paths Fluid-induced rotordynamic forces produced by the ﬂuid in an annular seal or in the leakage passage surrounding the shroud of a pump or turbine, are known to contribute substantially to the potential excitation forces acting on the rotor.
The present research. age from labyrinth seals, so they design the clearances of the labyrinth seal to be small. However, if the clearances are small, self-excited rotor vibra-tions are caused by the flow forces of the working fluid.
The origins of the exciting forces are at present only partially known as a steam whirl Size: KB. fluid film forces and the inertia force of the stator mass.
As data reduction to rotordynamic coefficients requires the fluid film force by itself, the stator inertia force must be subtracted from the load cell readings. With the mass of the stator known, this is done as follows: where Fy = -Fy + ms(d2/dt2)(-Fy/Ksy)File Size: KB.
The carry over coefficient is found to be a function of the geometry and non-dimensional flow parameters of the labyrinth seal tooth configuration. Carry over coefficient increases with tooth clearance, tooth width and Reynolds Number. The variation with shaft speed does not follow a certain pattern always and varies with shaft speed.
uniflorm flow are rotating blades, blade tip shrouds, and labyrinth seals. Such forces may even be correctable by current mass balancing techniques if the force and phase of the fluid effects are compatible with the modal,hapes,selected for balancing.
DETERMINATION OF ROTORDYNAMIC COEFFICIENTS FOR LABYRINTH SEALS AND. DETERMINATION OF ROTORDYNAMIC COEFFICIENTS FOR LABYRINTH SEALS AND APPLICATION TO ROTORDYNAMIC DESIGN CALCULATIONS P.
Weiser and R. Nordmann Department of Mechanical Engineering University of Kaiserslautern Kaiserslautern, Federal Republic of Germany In today's rotordynamic calculations File Size: KB. EOMETRY AND CFD MODEL OF THE SEAL. Seal Geometry. The straight labyrinth seal object of this study has four teeth fixed on the rotor lateral surface.
The 2D seal geometry - is shown in figure 1 and the seal dimensions are summarized in table 1. M eff. The seal working fluid is air. A cut section of the 3D fluid. Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example.
This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system by: 8. CFD analysis of ﬂuid ﬂow through the labyrinth seal 73 Figure 2: Fanno line for seal without extraction: v1 – begin volume, p i – inlet pressure, p o – outlet pressure, h – enthalpy, s – entrpopy.
Experimental researchs are too expensive and time consuming. Therefore, com. Impact Analysis of Pocket Damper Seal Geometry Variations on Leakage Performance and Rotordynamic Force Coefficients Using Computational Fluid Dynamics J.
Eng. Gas Turbines Power (April, ) Nonlinear Analysis of Rotordynamic Fluid Forces in the Annular Plain Seal by Using Extended Perturbation Analysis of the Bulk-Flow Theory Cited by: In this paper, stepped labyrinth seals with teeth on stator and teeth on rotor are considered.
Stepped labyrinth seal geometry is given in Fig. NT is the number of the teeth varies from 2 to 18 depending on the type of seal.
d is the height of the step. R s is the shaft radius. Shaft radius is same for each cavity for the straight labyrinth by: Minimizing unwanted leakage between stationary and rotating parts is the main function of annular seals.
A Mixed labyrinth seal (MLS) with two specially designed lateral teeth installed on a Staggered labyrinth seal (SLS) is proposed to improve seal performance.
A 3D computational fluid dynamics calculation model of MLS is set up. The twin vortex structure that appears in the seal Cited by: 3.
The tested seal is a short staggered three-teeth-on-stator labyrinth seal with a rotor band placed under the second tooth. Such a sealing configuration is typical for blade tip locations.
Geometry of the generic sealing configuration is shown in Figure 1. The mean diameter of the inlet is mm and its height is 2 Size: KB. These are the steady forces commonly referred to as the radial forces or radial thrust and are summarized in Brennen .
In this paper, we will not dwell on these forces. The other set of forces with which this paper will be concerned are the ﬂuid-induced rotordynamic forces that are caused by the displacement and motion of the axis of rotation. Computational Fluid Dynamic and Rotordynamic Study on the Labyrinth Seal Rui Gao Abstract The labyrinth seal is widely used in turbo machines to reduce leakage flow.
The stability of the rotor is influenced by the labyrinth seal because of the driving forces generated in the seal.Labyrinth seal is a key component for the safe and reliable operation of a turbine unit. This paper sets up a three-dimensional numerical model of a labyrinth seal with a tilting rotor based on a compressor eye seal which was studied by Computational Fluid Dynamics method and a test labyrinth seal.
The influence of the tilting rotor on the static and dynamic characteristics of labyrinth Cited by: 1. The incompressible flow in a labyrinth seal is computed using the ‘κ−ε’ turbulence model with a pressure-velocity computer code in order to explain leakage phenomena against the mean pressure gradient.
The flow is axisymmetric between a Cited by: