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Journal ArticleDOI

Dynamic Analysis of Rotor-Seal System Considering the Radial Growth Effect of the Seal

01 Mar 2020-Vol. 1510, Iss: 1, pp 012002

Abstract: Effect of the increase in operating speed, temperature and pressure ratio on turbomachine components must be studied and understood seriously. One of the major challenges is to choose a right initial clearance for seals considering the seal growth as it may affect rotor system dynamic characteristics and leakage performance. In the present study the dynamic response of the rotor system has been calculated considering the seal growth effect at each operating speed. It is been analyzed by the response plots and the orbital plots. The results show that the dynamic response of the system is influenced by radial growth of seal at lower pressure ratio and higher rotational speed. At higher pressure ratio the radial growth of seal has insignificant effect on rotor stability. In addition to these, the present study also emphasizes on the effect of the seal on the overall rotor system by comparing two different rotor-seal system.
Topics: Seal (mechanical) (57%), Rotor (electric) (57%), Turbomachinery (52%), Overall pressure ratio (51%), Rotational speed (51%)
References
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Journal ArticleDOI
J. S. Alford1Institutions (1)

230 citations


Journal ArticleDOI
Abstract: Clearance control is of paramount importance to turbomachinery designers and is required to meet today's aggressive power output, efficiency, and operational life goals. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, overheating downstream components and damaging interfaces, thus limiting component life. Designers have put renewed attention on clearance control, as it is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This work presents an overview of turbomachinery sealing to control clearances. Areas covered include: characteristics of gas and steam turbine sealing applications and environments, benefits of sealing, types of standard static and dynamics seals, advanced seal designs, as well as life and limitations issues.

171 citations


Journal ArticleDOI
Dara W. Childs1Institutions (1)
Abstract: A finite-length solution procedure is developed for perturbation equations which are based on Hirs' (1973) turbulent lubrication model. The equations apply to small motions about a centered position and include the influence of swirl and changes in Reynolds number due to perturbations in clearances. Numerical results are presented for a range of L/D ratios, with and without swirl. For zero swirl, changes in the L/D ratios show results which are similar to those obtained by Black and Jenssen (1970), but when L/D = 1, differences of about 15 percent appear. The results including swirl give physically insupportable results at small L/D ratios, such as a negative cross-coupled stiffness coefficient at L/D = 0.2. This result demonstrates that the complete Hirs turbulence model is not suitable for short seals with significant swirling flow.

119 citations


Journal ArticleDOI
J. K. Scharrer1Institutions (1)
Abstract: The basic equations are derived for a two-control-volume model for compressible flow in a labyrinth seal. The recirculation velocity in the cavity is incorporated into the model for the first time. The flow is assumed to be completely turbulent and isoenergetic. The wall friction factors are determined using the Blasius formula. Jet flow theory is used for the calculation of the recirculation velocity in the cavity. Linearized zeroth- and first-order perturbation equations are developed for small motion about a centered position by an expansion in the eccentricity ratio. The zeroth-order pressure distribution is found by satisfying the leakage equation while the circumferential velocity distribution is determined by satisfying the momentum equations. The first-order equations are solved by a separation of variable solution. Integration of the resultant pressure distribution along and around the seal defines the reaction force developed by the seal and the corresponding dynamic coefficients.

79 citations


Journal ArticleDOI
F. J. Dietzen1, R. Nordmann1Institutions (1)
Abstract: For modelling the turbulent flow in a seal the Navier-Stokes equations in connection with a turbulence (kappa-epsilon) model are solved by a finite-difference method. A motion of the shaft round the centered position is assumed. After calculating the corresponding flow field and the pressure distribution, the rotor-dynamic coefficients of the seal can be determined. These coefficients are compared with results obtained by using the bulk flow theory of Childs and with experimental results.

68 citations