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CFD-Aided Design of a Transonic Aeroelastic Compressor Rig
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2019 (English)In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 141, no 10, article id 101003Article in journal (Refereed) Published
Abstract [en]

This paper presents the results of computational fluid dynamics (CFD)-aided design calculations of a transonic linear cascade wind tunnel. The purpose of the wind tunnel is to generate data for the validation of numerical methods employed to calculate aerodynamic damping for forced response cases in transonic compressors. It is common for transonic wind tunnels to use transonic walls (perforated walls with controlled suction) to adjust the transonic flow in the experiment. Unfortunately, perforated walls are difficult to model in CFD simulations, and they complicate the validation process. One of the goals of the new tunnel is not to use perforated walls. The main difficulty in the design of a transonic linear cascade is achieving periodic flow for the central blades due to shock reflections from the side walls and the sensitivity of transonic flow to small changes in geometry. Other design constraints are the maximum available mass flow of 4.5 kg/s and the minimum required blade thickness of 2 mm for instrumentation. The purpose of the current CFD simulations is to determine the optimum geometry (sidewalls, tailboards, and throttle) of the tunnel with the goal of achieving near periodic flow conditions for the central blade channels at the similar condition in a typical transonic compressor.

Place, publisher, year, edition, pages
ASME , 2019. Vol. 141, no 10, article id 101003
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-267191DOI: 10.1115/1.4043884ISI: 000506906300005Scopus ID: 2-s2.0-85091274066OAI: oai:DiVA.org:kth-267191DiVA, id: diva2:1391213
Conference
15th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachinery (ISUAAAT), SEP 24-27, 2018, Oxford, ENGLAND
Note

QC 20200204

Available from: 2020-02-04 Created: 2020-02-04 Last updated: 2023-06-08Bibliographically approved
In thesis
1. Design, Optimization and Evaluation of a Transonic Aeroelastic Rig
Open this publication in new window or tab >>Design, Optimization and Evaluation of a Transonic Aeroelastic Rig
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The compressor is one of the most essential components of a modern turbomachinery engine. This component is exposed to vibrations that without proper design can damage structural integrity and lead to failure. Due to the unsteady flow that is inherent in compressors, characterized by transonic flow and high aerodynamic loading, the blades are prone to high cycle fatigue (HCF). Forced response assessments are needed to quantify the vibrational amplitude under resonance and determine the stresses for possible HCF problems. Resonance occurs when the blade’s natural frequency is excited by an external force. At specific frequencies, the resonant effect will significantly affect the performance of the compressor blade. In the forced response prediction, one of the crucial processes is the aerodynamic damping calculation. There are various models and numerical methods that are used for the damping prediction. However, there is a lack of experimental data for the numerical validation at high frequencies, which limits the research. A new aeroelastic rig is necessary to investigate the unsteady pressures when determining the aerodynamic damping in a transonic compressor.

The design of the new aeroelastic rig was developed in this thesis. The new transonic aeroelastic rig consists of a linear cascade wind tunnel with a vibrating blade driven by piezoelectric actuators. The primary layout was determined by a comparative discussion based on an overview of several aeroelastic rigs and transonic cascade wind tunnels. The blade profile was obtained from the GKN Virtual Integrated Compressor (VINK). The vital part was the design of the test section, which was optimized with the numerical simulations to obtain an optimal flow in the test rig. The transonic nozzle design was developed with the Foelsch method.

Numerical simulations were performed to evaluate the expected performance of the chosen test rig design. The veracity of the numerical model was checked by validation with experimental data obtained from the constructed test rig. Three different mode shapes and five cases with variable tip gaps were analyzed. The unsteady results provide a benchmark for the test rig. The unsteady distribution on the blade due to the vibration of each mode predicts the unsteady performance which will occur in the unsteady testing. The comparison with different tip gaps shows that these are significant for both periodicity and unsteady performance. Moreover, the study highlights the discrepancies in the unsteady perturbation behavior between the test rig flow and an ideal turbomachinery flow. This is due to system discrepancies is evaluated, and several are mostly unavoidable for future testing.

Abstract [sv]

Kompressorn är en av de viktigaste komponenterna i en modern turbomaskin. Den påverkas av vibrationer som utan noggrann design kan skada dess strukturella integritet och kan leda till maskinskador. På grund av det icke-stationära flödet hos kompressorer, som beskrivas som transsoniskt med höga aerodynamiskt last, är bladen benägna att utsättas för högcyklisk utmattning. Utvärderingar som belyser påtvingad respons behövs för att kvantifiera vibrationsamplituder vid resonans och att bestämma spänningarna för möjliga HCF-fel. Resonans uppstår nar bladets egenfrekvens exciteras av en extern kraft. Vid vissa frekvenser kommer resonans att ha en stark påverkan på kompressorbladets prestanda. Inom analysen av påtvingad respons är aerodynamiska dämpning en viktig beräkningsparameter. Det finns olika modeller och numeriska metoder för att prediktera dämpning. Däremot finns det lite experimentella data tillgängligt för numeriska valideringar vid höga frekvenser, som leder till begränsningar i forskningen.

En ny typ av rigg för aeroelasticitetsstudier behövs för att undersöka icke-stationära tryck som har relevans till aerodynamisk dämpning i en transsonisk kompressor. Riggens design utvecklas i denna avhandling. Den nya trans-soniska riggen består av en lineär kaskadvindtunnel med ett piezoelektrisk-drivet vibrerande blad. De primära egenskaperna bestämdes genom en komparativ diskussion baserad på en överblick av flera liknande riggar och transsoniska kaskadvindtunnlar. Bladets profil togs från GKN:s Virtuell integrerad kompressor (VINK). Den väsentliga delen bestod av testsektionens design, som var optimerad med numeriska simuleringar för att åstadkomma optimala flöde i riggen. Foelsch:s metod används för att designa testsektionens trans-soniska munstycke.

Numeriska simuleringar genomfördes för att utvärdera den förväntade prestandan hos riggens utvalda design. Modellens noggrannhet kontrollerades genom validering mot data tagit från den verkliga riggen. Tre olika mod-former och fem olika fall med varierande bladspetsavstånd analyserades. Icke-stationära resultaten används som referens mot riggens resultat. Bladets icke-stationära flödesprofil som skapats av mod-formers vibrationer kunde prediktera den icke-stationära prestandan vid experimentella försök. Jämförelsen mellan olika bladspetsavstånd visar dess betydelser gällande både periodicitet och icke-stationära prestanda. Dessutom understryks diskrepanser i det icke-stationära störningsbeteendet som finns mellan riggen och ett idealt flöde i en turbomaskin. Denna aspekt relateras till olika skillnader som är oundviklig hos den verkliga riggen. Icke-stationära tryck studerats och flera rekommendationer ges för framtida experiment.

Place, publisher, year, edition, pages
Sweden: KTH Royal Institute of Technology, 2021. p. 157
Series
TRITA-ITM-AVL ; 2021:22
Keywords
Transonic compressor, Aeroelastic rig, Design, CFD, Unsteady flow
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-295297 (URN)978-91-7873-861-8 (ISBN)
Public defence
2021-05-28, https://kth-se.zoom.us/j/67358883340, Stockholm, 09:00 (English)
Opponent
Supervisors
Available from: 2021-05-19 Created: 2021-05-19 Last updated: 2022-07-08Bibliographically approved

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Tian, SimengPetrie-Repar, PaulGlodic, NenadSun, Tianrui

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