| 1. |
- Ferreira da Silva, Janaina, et al.
(författare)
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Considering the Effects of Turbine Blade Cooling on Engine Performance Estimation
- 2017
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Ingår i: Proceedings of the 23rd ISABE conference 2017.
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Konferensbidrag (refereegranskat)abstract
- In gas turbines, a way to improve the engine performance is by increasing the Turbine Inlet Temperature (TIT). However, increasing TIT causes an increase in heat load of turbine components. A limit in the performance improvement is imposed by the permissible metal temperature. Engine running above the melting point of material might be achieved only by cooling turbine components or using Thermal Barrier Coating (TBC). This thermal management must be done to ensure safe and durable engine operation. The most common method to cool turbine components is bleed a portion of the compressor airflow and inject it on blades and disks. Unfortunately, the extraction has an adverse effect on engine performance compared with engine without bleed. In this paper, the cooling effects on engine performance estimation at preliminary design was analyzed. The engine configuration used in the study is a turboshaft – single spool gas turbine engine. The coolant parameters are estimated using the method developed by Young and Wilcock. The results showed that there is a marked difference on performance for uncooled and cooled turbine blades, highlighting the importance in considering the cooling on performance estimation since design preliminary phase. Ignoring the cooling in evaluation can cause up to 15% difference in net specific work.
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| 2. |
- Costa, Fabíola Paula, et al.
(författare)
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Aerodynamic Analysis of Conventional and Boundary Layer Ingesting Propellers
- 2023
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 145:1
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Tidskriftsartikel (refereegranskat)abstract
- The boundary layer ingestion (BLI) concept has emerged as a novel technology for reducing aircraft fuel consumption. Several studies designed BLI-fans for aircraft. BLI-propellers, although, have still received little attention, and the choice of open-rotors or ducted propellers is still an open question regarding the best performance. The blade design is also challenging because the BLI-propulsors ingest a nonuniform flow. These aspects emphasize further investigation of unducted and ducted BLI-propulsors and the use of optimization frameworks, coupled with computational fluid dynamics simulations, to design the propeller to adapt to the incoming flow. This paper uses a multi-objective NSGA-II optimization framework, coupled with three-dimensional RANS simulations and radial basis function (RBF) metamodeling, used for the design and optimization of three propeller configurations at cruise conditions: (a) conventional propeller operating in the freestream, (b) unducted BLI-propeller, and (c) ducted BLI-propeller, both ingesting the airframe boundary layer. The optimization results showed a significant increase in chord and a decrease in the blade angles in the BLI configurations, emphasizing that these geometric parameters optimization highly affects the BLI-blade design. The unducted BLI-propeller needs approximately 40% less shaft power than the conventional propeller to generate the same amount of propeller force. The ducted BLI-propeller needs even less power, 47%. The duct contributes to the tip vortex weakening, recovering the swirl, and turning into propeller force, as noticed from 80% of the blade span to the tip. However, the unducted and ducted BLI-configurations presented a higher backward force, 26% and 46%, respectively, compared to the conventional propeller, which can be detrimental and narrow the use of these configurations.
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| 3. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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A Propeller Model for Steady-State and Transient Performance Prediction of Turboprop and Counter-Rotating Open Rotor Engines
- 2018
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 140:7, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a methodology used for propeller performance estimation, which was implemented in an in-house modular program for gas turbine performance prediction. A model based on subsonic generic propeller maps and corrected for compressibility effects, under high subsonic speeds, was proposed and implemented. Considering this methodology, it is possible to simulate conventional turboprop architectures and counter-rotating open rotor (CROR) engines in both steady-state and transient operating conditions. Two simulation scenarios are available: variable pitch angle propeller with constant speed; or variable speed propeller with constant pitch angle. The simulations results were compared with test bench data and two gas turbine performance commercial software packages were used to fulfill the model validation for conventional turboprop configurations. Furthermore, a direct drive CROR engine was simulated using a variable inlet guide vanes (VIGV) control strategy during transient operation. The model has shown to be able to provide several information about propeller-based engine performance using few input data, and a comprehensive understanding on steady-state and transient performance behavior was achieved in the obtained results.
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| 4. |
- Tavares Silva, Vinícius, 1991
(författare)
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Aerodynamic Aspects of Propulsion Integration for Next-generation Commercial Aircraft
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Propulsion integration is one of the most challenging aspects of aircraft design. It requires a multidisciplinary approach involving aerodynamics, propulsion, structures, weight, noise, and control systems. The constant push for lowering fuel burn and noise, and the recent goals for radically reducing the environmental impact of aviation drive the aviation industry to improve state-of-the-art technology and investigate innovative engine/aircraft integration solutions. A way to improve the specific fuel consumption of aircraft engines is by lowering the fan pressure ratio and increasing the bypass ratio. This is accompanied by larger fan diameters, and consequently increased nacelle weight and drag. The next-generation transport aircraft will feature engines substantially larger than those in-service, which will require shorter and lighter nacelles so that the engine performance benefits are not outweighed by an increased nacelle weight and drag. In this thesis, this problem is approached by developing new methods for the aerodynamic design of conventional and ultra-short nacelles, following a multi-point design methodology that considers the most critical operating conditions within the flight envelope. A computational fluid dynamics-based framework has been built to design nacelles and evaluate their aerodynamic performance. A comprehensive analysis of the aerodynamic aspects of nacelle design and the main parameters for the design of ultra-short nacelles are identified. The installation of next-generation high-bypass turbofan engines also poses a major challenge to the aviation industry due to the limited space beneath the wings and stringent ground clearance constraints. Over-wing installed nacelles can be a potential solution for this problem, instead of the customary under-wing mounts. In this thesis, a framework for engine/aircraft integration aerodynamic design has been developed. The over-wing configuration is compared to conventional under-wing mounts in terms of aerodynamic performance. A novel method for wing redesign in the presence of the nacelle is proposed and an engine placement study is carried out. In addition, low-speed wind tunnel tests were conducted for two scale configurations. The first was a standalone powered nacelle whereas the second was a half-span powered over-wing mounted nacelle configuration. The aim was to investigate the impact of the engine power setting and angle of attack on the flow field for low-speed operating conditions.
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| 5. |
- Tavares Silva, Vinícius, 1991
(författare)
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Aerodynamic Design and Experimental Investigation of Short Nacelles for Future Turbofan Engines
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To achieve a higher propulsive efficiency, and hence reduced fuel burn and emissions, the next generation turbofan engines are expected to have higher bypass ratios and lower fan pressure ratios. However, the larger the bypass ratio, the larger becomes the fan and thus the nacelle. The result is an undesired increase in weight and nacelle drag. For this reason, advanced nacelle designs with shorter inlets and exhaust nozzles are necessary, so that the attained performance benefits are not outweighed by the increased installation drag and weight. This thesis presents a newly developed methodology for multi-point design of ultra-short nacelles. An integrated aerodynamic framework, based on parametric geometry generation and computational fluid dynamics (CFD) flow solutions was built and used for designing several ultra-short nacelle shapes and to evaluate their aerodynamic performance. The main design parameters and their influence in the flow field were investigated for the most critical operating conditions among the flight mission, such as cruise, high angle-of-attack (AoA) and crosswind. The aerodynamic performance of the designed nacelles was evaluated through a thrust and drag bookkeeping approach, and also by means of the distortion levels at the fan face. Furthermore, this work summarizes the main results obtained in an experimental aerodynamic investigation of a powered turbofan nacelle, conducted at the Chalmers low-speed wind tunnel. The impact of the engine angle-of-attack and the mass flow ratio (MFR) on the nacellle aerodynamic performance was investigated.
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| 6. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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Aerodynamic Installation Effects of Over the wing Mounted Ultra high bypass Engines
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to increase propulsive efficiency and decrease specific thrust, future aeroengines for commercial airliners will have to operate with higher bypass ratios and lower fan pressure ratios. This results in a substantial increase of the fan diameter. One major issue with the conventional under-wing installation of ultrahigh-bypass engines is the limited space underneath the wings. Integrating larger engines under-the-wings could require prohibitive increase in landing gear height and weight to attain an adequate ground clearance. One potential solution is to mount the engines over-the-wings, which would eliminate the ground clearance problem and, in addition, reduce ground noise. Over-wing nacelle installation acquired a bad reputation in the past since the benefits of such configuration would be often outweighed by poor aerodynamic performance. Nonetheless, some recent studies indicate that over-wing mounted nacelles could be a feasible integration option. This paper provides an aerodynamic evaluation of an over-the-wing mounted nacelle configuration compared with an under-the-wing configuration for a mid-cruise condition. The nacelles and pylons are designed by using an in-house tool for engine aircraft aerodynamic integration. The flow field is computed by means of Reynolds-averaged Navier-Stokes equations. The effects of wing/nacelle/pylon interference are investigated, and the aerodynamic performance of each configuration is evaluated by means of thrust and drag bookkeeping. Results show that the over-the-wing nacelle installation has increased the overall drag by 19.7 drag counts, when compared to a conventional under-wing mount, which was caused mainly due to a higher wing wave drag and pylon/nacelle interference drag.
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| 7. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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Influence of Variable Geometry Compressor on Transient Performance of Counter-Rotating Open Rotor Engines
- 2018
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 140:12
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Tidskriftsartikel (refereegranskat)abstract
- This work describes a methodology used for counter-rotating (CR) propellers performance estimation. The method is implemented in an in-house program for gas turbine performance prediction, making possible the simulation of the counter-rotating open rotor (CROR) architecture. The methodology is used together with a variable geometry compressor control strategy to avoid surge conditions. Two cases are simulated under transient operation for both fixed and variable geometry compressor. The influence of the variable geometry control on the transient performance of CROR engines is evaluated and a comprehensive understanding on the transient behavior of this type of engine could be obtained. It is shown that the use of the variable geometry compressor control does not significantly affect the overall engine performance, while avoiding the surge conditions, thus ensuring the engine operation safety.
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| 8. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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MULTIPOINT AERODYNAMIC DESIGN OF A NACELLE FOR AN ELECTRIC FAN
- 2022
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Ingår i: ICAS Proceedings. - 2958-4647.
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Konferensbidrag (refereegranskat)abstract
- Attention to aircraft electrification has been growing quickly since such technology carries the potential of drastically reducing the environmental impact of aviation. This paper describes the re-design of a nacelle for an electric fan, which is developed as part of the EleFanT (Electric Fan Thruster) project. A multipoint nacelle design approach was carried out. Initially the nacelle shapes were optimized for a cruise condition by employing an evolutionary genetic algorithm (GA). The flow field around the nacelles was calculated by conducting 2D axisymmetric computational fluid dynamics (CFD) simulations, and the objective functions were computed by means of thrust and drag bookkeeping. It was found that the optimizer favored two types of nacelle shapes that differed substantially in geometry. The designs were referred to as low spillage and high spillage types. The optimum low spillage and high spillage cases were selected and investigated further by the means of 3D CFD simulations at cruise and at an end of runway takeoff condition, where the nacelle is subjected to high angle of attack. Whilst the low spillage case provided a slightly better performance at cruise, it presented high levels of distortion and boundary layer separation at takeoff, requiring a substantial shape modification. The high spillage case performed well at takeoff; however, supersonic velocities could be observed at the cowling when it was subjected to incoming flow at an angle of attack. Nonetheless, such problem was easily corrected by drooping the inlet. Due to its superior performance at takeoff, the drooped high spillage design type was recommended.
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| 9. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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Multipoint aerodynamic design of ultrashort nacelles for ultrahigh-bypass-ratio engines
- 2022
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Ingår i: Journal of Propulsion and Power. - 1533-3876 .- 0748-4658. ; 38:4, s. 541-558
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a newly developed methodology for multipoint aerodynamic design of ultrashort nacelles for ultrahigh-bypass-ratio turbofan engines. An integrated aerodynamic framework, based on parametric geometry generation and flowfield solution via three-dimensional Reynolds-averaged Navier-Stokes equations, was built and used for designing several ultrashort nacelle shapes and to evaluate their aerodynamic performance. An approach for modeling the inlet-fan coupling is presented and validated. A design strategy is introduced, and various test cases are evaluated under the following critical operating conditions: midcruise, low speed/high angle of attack, and pure crosswind. The major design parameters are highlighted and their influence in the flowfield is discussed in detail for all the chosen flight conditions. Performance was evaluated by assessing inlet flow distortion and by bookkeeping of thrust and drag. The framework has proven to be suitable for designing high-performance nacelles capable of operating under critical flight conditions, without flow separation or high levels of distortion. Drooping the inlet by 4 deg is shown to reduce the drag at cruise by 1.9%, which also has a large beneficial impact on internal lip separation at high-incidence conditions. Furthermore, crosswind was identified as the most severe of the conditions, requiring a drastic reshaping of the nacelle to avoid internal lip separation. Two final nacelle designs were compared: the first allowed inlet separation under a 90 deg crosswind condition, whereas the second was reshaped to be separation-free under all operating conditions. Reshaping to avoid separation has increased drag by 5.1% at cruise.
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| 10. |
- Tavares Silva, Vinícius, 1991, et al.
(författare)
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Over-wing integration of ultra-high bypass ratio engines: A coupled wing redesign and engine position study
- 2023
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Ingår i: Aerospace Science and Technology. - 1270-9638. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- The integration of next-generation high-bypass turbofan engines poses a major challenge to the aeronautical industry due to the larger fans necessary to achieve more fuel-efficient engines. The limited space underneath the wings and the strict ground clearance constraints bring the necessity to investigate solutions other than the conventional under-wing mounted engines. Over-wing installed nacelles have the potential to solve the ground clearance issue and, in addition, might reduce ground noise due to acoustic shielding from the wing. Nevertheless, a strong and complex coupling between aerodynamics and propulsion is the result of such integration choice, and traditional design practices may result in configurations with prohibitively high drag penalties. This paper presents a novel wing redesign method, specifically developed for over-wing mounted engines. The wing is reshaped to recover the spanwise lift distribution of the clean airframe (wing-body) configuration, for a single aisle airliner at a cruise condition. The wing redesign is conducted along with an engine position sensitivity study, in which the wing is reshaped for different engine axial and vertical positions. The coupling between propulsion and aerodynamics is thoroughly investigated, as well as the interaction and interference effects between the wing, pylon, and nacelle. Moreover, the best over-wing solution is compared to a baseline under-wing mounted nacelle. Results show that, by applying the developed method, an overall drag reduction of 17.65 counts, or 6.4%, was obtained, compared to the initial over-wing configuration, comprising the original wing and baseline engine position. Nonetheless, the best over-wing nacelle design is still 5.58 counts, or 2%, higher in overall drag compared to the baseline under-wing mounted nacelle case.
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