| 1. |
- Assato, Marcelo, et al.
(författare)
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PERFORMANCE BENEFITS OF A FAN ON BLADE – FLADE – FOR A VARIABLE CYCLE ENGINE
- 2022
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Ingår i: 33th Congress of the International Council of the Aeronautical Sciences. - 2958-4647. - 9781713871163 - 9781713871163 ; 7, s. 4888-4902
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Konferensbidrag (refereegranskat)abstract
- Variable cycle engines promise to enable adaptive cycles that give close to optimal performance over a wide range of conflicting mission requirements, such as low altitude high speed flight and supercruise still providing excellent range. Modelling such engines pose challenges for general purpose software since variable geometry gas paths modify the underlying set of equations being solved. It is possible to use multiple engine models transferring design data between the models. This, however, creates a high risk for inconsistency and modelling error. It is more attractive if the solutions obtained could be determined using the same model. In this work an in-house software was developed to model an Adaptive Cycle Engine (ACE). This development was used to show how variable cycle mode switches can be integrated into general purpose performance tools. The variable cycle engine uses a FLADE, which is a "fan on blade" component, to extend its range and to provide improved subsonic performance. The individual impact of the components, its effect on propulsion performance parameters and in the engine installation were analyzed as the main results. The contribution from this paper is thus two-fold, firstly the paper goes ahead and proposes new methods for the simulation of mode switching in generic performance tools by introducing dynamic equation systems. Secondly, the paper then studies the FLADE component and its potential performance benefits if added to a conventional turbofan architecture.
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| 2. |
- Grönstedt, Tomas, 1970, et al.
(författare)
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Design Considerations of Low Bypass Ratio Mixed Flow Turbofan Engines with Large Power Extraction
- 2022
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Ingår i: Fluids. - : MDPI AG. - 2311-5521. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of extracting large amounts of electrical power from turbofan engines is becoming increasingly desirable from an aircraft perspective. The power consumption of a future fighter aircraft is expected to be much higher than today's fighter aircraft. Previous work in this area has concentrated on the study of power extraction for high bypass ratio engines. This motivates a thorough investigation of the potential and limitations with regards to performance of a low bypass ratio mixed flow turbofan engine. A low bypass ratio mixed flow turbofan engine was modeled, and key parts of a fighter mission were simulated. The investigation shows how power extraction from the high-pressure turbine affects performance of a military engine in different parts of a mission within the flight envelope. An important conclusion from the analysis is that large amounts of power can be extracted from the turbofan engine at high power settings without causing too much penalty on thrust and specific fuel consumption, if specific operating conditions are fulfilled. If the engine is operating (i) at, or near its maximum overall pressure ratio but (ii) further away from its maximum turbine inlet temperature limit, the detrimental effect of power extraction on engine thrust and thrust specific fuel consumption will be limited. On the other hand, if the engine is already operating at its maximum turbine inlet temperature, power extraction from the high-pressure shaft will result in a considerable thrust reduction. The results presented will support the analysis and interpretation of fighter mission optimization and cycle design for future fighter engines aimed for large power extraction. The results are also important with regards to aircraft design, or more specifically, in deciding on the best energy source for power consumers of the aircraft.
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| 3. |
- Rosell, Daniel, 1979, et al.
(författare)
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LOW BPR TURBOFAN PERFORMANCE WITH POWER EXTRACTION
- 2022
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Ingår i: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022. ; 6, s. 4382-4397
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Konferensbidrag (refereegranskat)abstract
- Military aircraft require more electrical power than they used to do. The increased power consumption is due to a transition from pneumatic and hydraulic systems to electrical and the introduction of new, more power consuming equipment. This paper summarizes an engine performance study, performed with a modeled low bypass ratio mixed flow turbofan engine, where power is extracted from the low-pressure shaft, the highpressure shaft or a combination of the two. High-pressure shaft power extraction results in a considerable turbine inlet temperature increase. If the operating point has sufficient margin to the maximum turbine inlet temperature limit and if the power extraction is acceptable from an operability point of view, power can be extracted from the high-pressure shaft without causing much penalty on engine thrust. If the engine is running close to its maximum turbine inlet temperature, which is typically the case at low altitude and high aircraft speed, power extraction from the low-pressure shaft could be a better alternative due to the lower turbine inlet temperature increase. This gives a higher margin to the maximum turbine inlet temperature limit. However, if the full potential of low-pressure shaft power extraction is to be utilized, the high-pressure compressor must have some aerodynamic overspeed margin for the low-pressure shaft power extraction case. At part power, the lower specific thrust of the low-pressure shaft extraction case compared to the high-pressure shaft power extraction case, is favorable from a propulsive efficiency and fuel consumption perspective.
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| 4. |
- Rosell, Daniel, 1979
(författare)
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Power Extraction in Military Aircraft
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Military aircraft require more and more power. Pneumatic and hydraulic systems are being replaced by electrical equipment and new, power consuming equipmentis introduced in the aircraft. Increased power extraction brings new challenges for the aircraft jet engine, both in terms of operability and with regards to engine performance. This thesis describes how the engine performance of a conventional low bypass ratio mixed flow turbofan engine is affected by power extraction from the highpressure shaft, the low-pressure shaft or a combination of the two. A twin-spool low bypass ratio mixed flow turbofan engine has been developed in a Chalmers in-house tool to evaluate engine performance in different parts of the flight envelope. In order to evaluate the impact of aircraft/engine interaction on flight performance, an aircraft performance tool has been developed as well. A turbine inlet gas temperature increase is required when power is extracted from the HP or LP shaft. This temperature increase is more considerable if power is extracted from the high-pressure shaft, increasing specific thrust and specific fuel consumption. When the engine is running close to, or at the maximum turbine inlet temperature limit, power extraction will have a detrimental impact on the engine performance, whether power is extracted from the high-pressure shaft or the low-pressure shaft, but the thrust reduction will be more substantial if power is extracted from the high-pressure shaft. When the engine is running close to or at the maximum overall pressure ratio limit, the thrust reduction due to high-pressure shaft power extraction is more moderate compared to the low-pressure shaft power extraction case, provided that the required temperature increase is acceptable from an engine operability perspective.
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