Research Papers: Gas Turbines: Structures and Dynamics

Optimization of the Straight-Through Labyrinth Seal With a Smooth Land

[+] Author and Article Information
Artur Szymański

Silesian University of Technology,
Gliwice 44-100, Poland
e-mails: aarturszymanski@gmail.com;

Włodzimierz Wróblewski

Silesian University of Technology,
Gliwice 44-100, Poland
e-mail: wlodzimierz.wroblewski@polsl.pl

Daniel Frączek

Silesian University of Technology,
Gliwice 44-100, Poland
e-mail: daniel.fraczek@polsl.pl

Krzysztof Bochon

Silesian University of Technology,
Gliwice 44-100, Poland
e-mail: Krzysztof.bochon@polsl.pl

Sławomir Dykas

Silesian University of Technology,
Gliwice 44-100, Poland
e-mail: slawomir.dykas@polsl.pl

Krzysztof Marugi

Avio Poland,
Bielsko-Biala 43-300, Poland
e-mail: krzysztof.marugi@avioaero.com

1Present address: Centre for Propulsion Engineering, Cranfield University, College Rd, Cranfield, Bedfordshire MK43 0AL, UK.

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 25, 2018; final manuscript received June 29, 2018; published online August 30, 2018. Editor: Jerzy T. Sawicki.

J. Eng. Gas Turbines Power 140(12), 122503 (Aug 30, 2018) (9 pages) Paper No: GTP-18-1338; doi: 10.1115/1.4040767 History: Received June 25, 2018; Revised June 29, 2018

This paper presents the methodology and results of the optimization of a straight-through labyrinth seal with two inclined fins against smooth-land. The optimization was performed using commercial tools implemented in the ANSYS environment, such as goal-driven optimization. The response surfaces were created based on Latin hypercube samples found from computational fluid dynamics (CFD) calculations. The CFD solver, using a steady-state scheme with the k–ω shear stress transport (SST) turbulence model, was applied. A screening algorithm was used to find the best candidates on the response surfaces. The objective function adopted in the labyrinth seal optimization was the minimization of the discharge coefficient value. A wide range of parameters of the fins position and shape were taken into account, with physically justified degrees-of-freedom. The optimization results were supported by the results of an in-house experiment performed on a stationary, linear test rig. The test rig was fed by a high-capacity vacuum air blower with high-precision hot-wire anemometry mass flow evaluation. The reductions in the leakage significantly exceed the uncertainties of the CFD model and the test rig accuracy. The factors that had the most substantial impact on the leakage reduction were the location, inclination, and thickness of the fins. The experimental results were compared with the calculations and the optimization effects, highlighting some tendencies in the labyrinth seal flow behavior. Good agreement was obtained between the optimization results and the experimental data, proving that the presented methodology is sufficient for the labyrinth seal optimization.

Copyright © 2018 by ASME
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Fig. 1

Reference geometry under analysis

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Fig. 2

Fluid domain computational model with boundary conditions

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Fig. 3

View of a selected numerical mesh for a seal with two inclined fins

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Fig. 4

Mesh study results

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Fig. 5

Vacuum installation intended for experimental testing of labyrinth seals: 1a. testing section inlet, T0, p0 evaluation, 1b. HWA probe no. 1 (3.5 m downstream the pipe inlet, ambient conditions), 2. testing section with a measurement system, 3a. HWA probe no. 2 (7 m downstream the testing section, low-pressure conditions), 3b. International Society of Automation orifice plate (2m downstream the HWA probe 3a), 4. secondary air inlet, 5. DN 100 valve, 6. DN 50 valve, 7. and 9. cut-off valve, 8. 3 m3 pressure vessel, 10. roots air blower, 11. exhaust to the environment.

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Fig. 6

Test rig cross section

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Fig. 7

Test rig cross section—enlarged fragment of the labyrinth and the facing specimen area

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Fig. 8

Experimental and CFD results of the discharge coefficient for the reference case

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Fig. 9

Optimization flowchart

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Fig. 10

Tools used in the optimization process

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Fig. 11

Variations in CD values as a function of the relative fin height and position

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Fig. 12

Variations in CD values as a function of the FFA and relative fin tip thickness

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Fig. 13

Labyrinth seal with a smooth land—reference geometry (black line) and optimized geometry—C1 (dashed line)

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Fig. 14

CD global sensitivity to input parameters—smooth land

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Fig. 15

CD versus load—reference and optimal seal—C1

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Fig. 16

Velocity distribution in the area over the seal. Optimized versus reference.

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Fig. 17

Static pressure distribution in the reference labyrinth seal with a smooth land (clearance s/FHref = 0.075)

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Fig. 18

Static pressure distribution in the optimized labyrinth seal (C1) with a smooth land (clearance s/FHref = 0.075)



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