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| 2. |
- Axelsson, Lars-Uno, 1979
(författare)
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A Large-Scale Facility for Investigation of Intermediate Turbine Ducts: Design, Implementation and Initial Tests
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intermediate turbine ducts are used in modern multi-spool jet engines for guiding the flow from the high-pressure turbine to the low-pressure turbine. The demand for lighter, more efficient and more environmentally friendly aircraft engines requires the new jet engines to have higher by-pass ratios. This leads to a demand on the intermediate turbine ducts to be more "aggressive", i.e. to have larger radial offset, and to be shorter and more diffusing. Unfortunately the flow phenomena that occur in such ducts are both complicated and poorly understood, and current numerical tools are of limited value. Therefore, in order to make these ducts more aggressive, a better understanding of the flow inside intermediate turbine ducts is necessary. As part of an effort to overcome this problem a new, large-scale, low-speed turbine facility has been design and constructed at Chalmers University ofTechnology.This thesis describes the design of the facility, with an emphasis on the intermediate turbine duct section. The design is based on general guide-lines for low-speedwind tunnels together with CFD and FEA. The facility is expected to provide detailed understanding of the flow physics within these intermediate turbine ducts, as well as provide high-quality data for validation of numerical simulations. This thesis also contains initial measurements used for implementation of the measurementtechniques to the facility.
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- Axelsson, Lars-Uno, 1979, et al.
(författare)
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Evaluation of the flow in an intermediate turbine duct at off-design conditions
- 2008
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Ingår i: ICAS 2008, 26th international congress of the aeronautical sciences, Alaska, August 2008. - 9781605607153 ; 2, s. 3286-3295
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Konferensbidrag (refereegranskat)abstract
- Intermediate turbine ducts are used in modern turbofan engines for connecting the highpressure turbine with the low-pressure turbine. The demands for engines with higher by-pass ratios require these ducts to be more "aggressive", i.e., to have a larger radial off-set and to be shorter. However, the flow in the intermediate turbine ducts are complex and therefore difficult to predict. Therefore a better understanding of the flow physics is necessary and measurements for CFD validation are needed. This paper presents time-averaged measurements of the flow in a state-at-the-art intermediate turbine duct with an upstream high-pressure turbine present. The investigation focuses on the intermediate turbine duct flow field development for different turbine conditions. The measurements consist of area traverses with a five-hole pressure probe at different axial locations within the intermediate turbine duct. In addition, a discussion of the endwall static pressure distribution and the overall pressure losses for the different conditions are done.
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| 5. |
- Axelsson, Lars-Uno, 1979
(författare)
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Experimental investigation of the flow field in an aggressive intermediate turbine duct
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intermediate turbine ducts are used for connecting thehigh-pressure turbine to the low-pressure turbine in turbofan engines. In order to meet the demands for more efficient and environmentally friendly jet engines, future intermediate turbine ducts need to have larger radial off-sets without increasing their length. In addition, reducing the length of the intermediate turbine duct reduces the weight of the engine.This thesis describes a detailed measurement campaign of anaggressive intermediate turbine duct. Its length was about 20% shorter than conventional engines with similar characteristics; hence the word aggressive. The first part of the thesis reports briefly the design and construction of the large-scale, low-speed turbine facility that was a part of this project. The turbine stage provided proper inlet boundary conditions for the downstream intermediate turbine duct. The second part of this thesis discusses the results from measurements, including endwall flow visualization, endwall static pressure measurements, 5-holepressure probe measurements and time-resolved and phase-resolved two-component hot-wire measurements. The measurements are expected to provide a useful database for validation of computational tools, especially since they contain detailed information about both the average flow and the turbulence.From the measurements no endwall flow separation due to theshortening of the duct could be detected. It was also found that the break up of the tip leakage flow formed a pair ofcounter-clockwise rotating vortices for each turbine vane sector. The phase-resolved measurements indicated that these were the wing tip vortices from the rotor blade that became stationary as the flow proceeded downstream. The phase-resolved measurements together with spectral analysis revealed that immediately downstream the turbine the flow was highly unsteady. But by the time the flow reached the low-pressure turbine vanes unsteady effects had been reduced and the flow was dominated by stationarystructures.
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| 6. |
- Axelsson, Lars-Uno, 1979, et al.
(författare)
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Experimental investigation of the time-averaged flow in an intermediate turbine duct
- 2008
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Ingår i: GT2008-50829. Proceedings of ASME Turbo Expo 2008: Power for Land, Sea and Air, June 9-13, 2008, Berlin, Germany. - 9780791843161 ; 6:PART B
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Konferensbidrag (refereegranskat)abstract
- Intermediate turbine ducts are used in modern multi-spool jet engines to connect the high pressure turbine with the lowpressure turbine. The trend towards turbofan engines with larger by-pass ratios requires the radial off-set between the high-pressure and low-pressure turbines to increase with a corresponding increase in radial off-set for the intermediate turbine ducts. Other improvements of the ducts is to make them shorter and more diffusing but this strive towards more aggressive design increases the risk for separation. This paper deals with an experimental investigation of the time-averaged mean flow field and turbulence development in an aggressive intermediate turbine duct (downstream a rotating turbine stage) using a 5-hole probe and 2-component hot-wire anemometry. In addition the duct endwall static pressure distribution is discussed. The investigation revealed the complex flow structure development within the duct, where corotating vortices emanating from the break-up of the tip gap shear-layer dominates the flow pattern.
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| 7. |
- Axelsson, Lars-Uno, 1979, et al.
(författare)
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Fourier decomposed turbulence measurements downstream of a high-pressure turbine stage
- 2008
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Ingår i: 2008 ASME Fluids Engineering Division Summer Conference, FEDSM 2008; Jacksonville, FL; United States; 10 August 2008 through 14 August 2008. - 9780791848418 ; 2, s. 177-182
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Konferensbidrag (refereegranskat)abstract
- This forum paper discusses phase-resolved turbulence measurements of the flow downstream of an axial turbine, and especially how phase-resolved measurements compare to time-resolved measurements. The time-resolved spectra produced higher velocity fluctuations than the corresponding phase-resolved spectra even when the periodic component was filtered out from the time-resolved measurements. The phase-resolved spectrum effectively removes all the peaks in the spectrum except for the ones associated with the blade-passage frequency.
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| 9. |
- De Oliveira Santos, F., et al.
(författare)
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Study of 19Na at SPIRAL
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 24:2, s. 237-247
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Tidskriftsartikel (refereegranskat)abstract
- The excitation function for the elastic-scattering reaction p( 18 Ne, p) 18 Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus 19 Na. In addition, two-proton emission events have been identified and are discussed.
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| 10. |
- Johansson, Peter, 1973, et al.
(författare)
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Numerical and experimental analysis of the flow in an aggressive intermediate turbine duct
- 2009
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Ingår i: 2009 ASME Turbo Expo; Orlando, FL; United States; 8 June 2009 through 12 June 2009. - 9780791848883 ; 7:PART B, s. 867-874
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Konferensbidrag (refereegranskat)abstract
- Multi-spool turbofan engines have intermediate ducts connecting the high-pressure turbine with the low-pressure turbine. The demands for more efficient and environmentally friendly jet engines force future turbofan engines to have higher by-pass ratios. This leads to that the radial off-set between the turbine stages increases and therefore the radial off-set of the intermediate duct has to increase. In order to save fuel consumption it is desirable to decrease engine weight and thus the duct should be made as short as possible. The flow in the intermediate duct is complex, so safely shortening the duct requires a thorough understanding of the flow physics in order to be able to accomplish this in a controlled manner. The present investigation focus on a joint experimental and numerical investigation of an intermediate duct configuration. The main purpose of the numerical simulation is to obtain an insight into the current capabilities of numerical simulations for these kinds of complex flow. The conclusion is that the numerical simulations manage fairly well to capture the total pressure and swirl angle profile from about 20% to 80% span. Also, the hub and shroud pressure profiles are well predicted while the total pressure loss is overpredicted in the numerical simulations.
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