Theory Versus Experiment for the Rotordynamic Coefficient of Labyrinth Gas Seals: Part II—A Comparison to Experiment

Childs, Dara W.; Scharrer, J. K.

doi:10.1115/1.3269514

Cited by 63 publications

(46 citation statements)

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“…The results obtained with current code labeled by "Fuerst, one volume" are compared to experimental results of Childs and Scharrer [10], "classical" one control volume code [1], and with the two control volumes code [11]. One can see that the results for cross coupled stiffness and direct damping corresponds very well to experimental data as well as to results obtained with other codes.…”

Section: Validationsupporting

confidence: 54%

“…The code is validated against experimental data [10] and numerical results of other authors using two variants of "classical" bulk-flow method for the case of a lookthrough seal with 16 stator teeth. The results show that the cross-coupled stiffness and direct damping coefficients are predicted in accordance to available data.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless the description of the experimental apparatus states that the rotor makes linear side-to-side motion [10]. Similarly the "classical" perturbation based codes including those of [11] assume elliptical motion.…”

Section: Validationmentioning

confidence: 99%

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The application of automatic differentiation techniques for the prediction of rotor-dynamic coefficients of labyrinth seals

Fürst

2016

EPJ Web of Conferences

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Abstract. The article describes the development of bulk-flow code for the prediction of rotor-dynamic coefficients of labyrinth seals. The code is based on the so-called single control volume approach by Childs and Scharrer [1] and the the forces are evaluated using the automatic differentiation technique. The resulting code is very simple and provides reasonable predictions of stiffness and damping coefficients at short computational time.

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Section: Validationsupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

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The application of automatic differentiation techniques for the prediction of rotor-dynamic coefficients of labyrinth seals

Fürst

2016

EPJ Web of Conferences

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“…Afterwards, also on the basis of the experimental observation of the peculiar flow in the cavity and CFD calculations by other authors such as Iwatsubo et al (1982); Rhode and Nail (1992); Rhode et al (1993); Scharrer (1988) modified the bulk model in a two-volume one. A quite limited comparison of the performance of the two models is reported in Childs and Scharrer (1988).…”

Section: Introductionmentioning

confidence: 99%

Theoretical Rotordynamic Coefficients of Labyrinth GasSeals: a Parametric Study on a Bulk Model

Forte

Latini

1998

International Journal of Rotating Machinery

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To date, available mathematical bulk models for the determination of linearized rotordynamic coefficients of labyrinth gas seals yield results which are not always in good agreement with the experimental ones. The object of this work is to discuss the limits of these models and to point out possible improvements and aspects that need further investigation.After a study of the steady flow characteristics with an FEM code, a parametric computer program, based on a known two-volume model, has been developed. A perturbation approach has been applied to the governing equations of the bulk model to calculate the stiffness and damping coefficients. Predicted coefficients are compared to the results of an earlier onevolume model.The model has also been tested with different expressions of the axial velocities in the two volumes and different laws for leakage and shear stress. The theoretical results are compared to the published experimental ones, pointing out the small effect of the various parameters in improving the correlation and the need of more complex models.

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“…Comparisons between Scharrer's theory and test results have been presented previously by Childs and Scharrer (1988) for teet h-on-stator (smooth-rotor) and teeth-on-rotor (smooth-stator) seals and by Hawkins and Childs (1988) for teethon-rotor seals with honeycomb stators. These results were for 5.08 cm long seals with the original 7.1 bar supply pressures at three clearances and showed generally reasonable agreement between theory and experiments.…”

Section: Labyrinth-seal Bow Fieldmentioning

confidence: 99%

Seal-Rotordynamic-Coefficient Test Results for a Model SSME ATD-HPFTP Turbine Interstage Seal With and Without a Swirl Brake

Childs

Ramsey

1991

Journal of Tribology

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Test results are presented and compared to theory for a model Space Shuttle Main Engine(SSME) Alternate Turbopump Development(ATD) High-Pressure Fuel Turbopump (HPFTP) with and without swirl brakes. Tests are conducted with s u p ply pressures out to 18.3 bars and speeds out to 16,000 rpm. Seal back pressure is controlled to provide four pressure ratios at all supply pressures. Three inlet guide vanes are used to provide the following three fluid prerotation cases: (a) no prerotation, (b) moderate prerotation in the direction of rotation, and (c) high prerotation in the direction of rotation. Test results demonstrate the pronounced favorable influence of the swirl brake in reducing the seal destabilizing forces. Without the swirl brake, the cross-coupled stiffness k increases monotonically with increasing inlet tangential velocity. With the swirl brake, k tends to either be constant or decrease with increasing inlet tangential velocity. Direct damping either increases or remains relatively constant when the swirl brake is introduced. Direct stiffness is relatively unchanged. No measurable differences in leakage were detected for the seal with and without the swirl brake.Comparisons between Scharrer's(l988) theory and measurements for the seal without a swirl brake indicate that the predictions can be used to provide design guide1ine.s only. Specific predict ions for rotor dynamic coefficients should be treated cautiously, since systematic differences were observed between theory and experiment due to changes in running speed, supply pressure, and pressure ratio.

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Theory Versus Experiment for the Rotordynamic Coefficient of Labyrinth Gas Seals: Part II—A Comparison to Experiment

Cited by 63 publications

References 0 publications

The application of automatic differentiation techniques for the prediction of rotor-dynamic coefficients of labyrinth seals

The application of automatic differentiation techniques for the prediction of rotor-dynamic coefficients of labyrinth seals

Theoretical Rotordynamic Coefficients of Labyrinth GasSeals: a Parametric Study on a Bulk Model

Seal-Rotordynamic-Coefficient Test Results for a Model SSME ATD-HPFTP Turbine Interstage Seal With and Without a Swirl Brake

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