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Research Project
Associate Laboratory of Energy, Transports and Aerospace.
Funder
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Publications
The impact of revolutionary aircraft designs on global aviation emissions
Publication . Abrantes, Ivo; Ferreira, Ana F.; Magalhães, Leandro; Costa, Mário; Silva, André
The discussion about the environmental impact caused by aviation has gained greater prominence due to the increased demand for this sector and, consequently, the increase in the number of flights. Environmental concerns have stimulated the development of novel approaches to reduce pollutants and CO2 emissions. This study aims to assess the impact of disruptive concepts on commercial aircraft by reducing CO2 emissions by 50% by 2050. In this regard the fleet system dynamics model is used to assess the effects of technological progress on future air transport systems. It accounts for the manufacturer’s production capabilities and current projections and forecasts on the needs and evolution of global air transport, as well as their expected entry into service. The main factors reported were production capacity, year of entry of the technology/concept, and the transport capacity and range of aircraft. The sensitivity study on the production capacity of new aircraft/concepts showed that with a 15% increase, emissions can be reduced between 1 and 2.6%, depending on the case and scenario. On the other hand, increasing the aircraft production capacity could lead to a problem of overcapacity.
Real-time optimization of wing drag and lift performance using a movable leading edge
Publication . Camacho, E. A. R.; Silva, Maíra Martins da; Silva, A. R. R.; Marques, Flávio D.
A real-time optimization strategy can provide any system with a considerable boost in performance on the fly, which in real-world applications can be translated to lower energy consumption or higher efficiency. This study investigates the particular case of using real-time optimization to improve wing aerodynamic performance with a dynamically activated deflectable leading edge. Its activation aims to minimize drag and maximize lift and is governed by real-time and gradient-based optimization. An extension to a classic method is suggested to enhance gradient estimation accuracy. Experimental data are obtained at a Reynolds number of
with the wing fixed at five positions. For each of these positions, optimal leading-edge deflections are found. The results indicate that deflecting the leading edge has a negligible impact on drag and lift before the stall onset. However, the reduction in the pitching moment cannot be ignored. When the wing is experiencing a proper stall, the movable leading edge yields remarkable enhancements, with the lift being approximately raised by 45% together with a substantial increase in the critical angle of attack. The findings highlight the potential of real-time optimization in experimental aerodynamic studies, reinvigorating its application in improving aircraft performance.
Fast Flapping Aerodynamics Prediction Using a Recurrent Neural Network
Publication . Pereira, João A. F.; Camacho, Emanuel A. R.; Marques, Flávio D.; Silva, A. R. R.
One of the major tasks of aerodynamics is the study of the flow around airfoils. While most conventional methods deal well with steady flows, unsteady airfoils, like the ones on helicopter blades, are subject to such complex dynamic flows that their study can impose substantial difficulties. However, recent applications of machine learning, in the form of neural networks, have shown very promising results when dealing with complex dynamic aerodynamic phenomena. For this reason, this paper proposes the implementation of a recurrent neural network for the time-wise prediction of the lift, momentum, and drag coefficients for an airfoil subject to plunging motion, using the 𝑅𝑒, k, h, 𝑘ℎ, and the time history of the effective angle of attack as inputs. Results from early training already suggest the network’s capability to approximate the desired outputs, even if with some limitations. However, the network configuration is flexible enough to be fed with either experimental or numerical data in the future.
Predicting the NACA0012-IK30 Airfoil Propulsive Capabilities with a Panel Method
Publication . Camacho, E. A. R.; Marques, Flávio D.; Silva, A. R. R.
Unsteady airfoils play a pivotal role in comprehending diverse aerospace applications, being one of those flapping propulsions. The present paper studies this topic by bringing back an old unsteady panel method to juxtapose its results against CFD data previously obtained. The central objective is to revive the interest in these reduced order models in the topic of unsteady airfoils, which can be extended to model highly nonlinear effects while keeping computational resources fairly low. The findings reveal that while the potential flow-based UPM (Unsteady Panel Method) struggles to accurately capture the airfoil’s propulsive power, it remains adept at estimating consumed power. Moreover, an investigation into the pressure coefficient shows the potential benefits of UPM in contexts where flow separation can be disregarded. Despite inherent limitations, these simplified methodologies offer an effective preliminary estimation of flapping airfoil propulsive capabilities.
Modelling a Loop Heat Pipe as Heat Switch for Transient Application in Space Systems
Publication . Castanheira, João Pedro Conceição; Dias, Nicole G.; Melício, Rui; Gordo, Paulo; Silva, André; Pereira, Roger Michael
Heat switches are devices for controlling heat flow in various applications, such as electronic devices, cryogenic cooling systems, spacecraft, and rockets. These devices require non-linear transient thermal simulations, in which there is a lack of information. In this study, we introduce an innovative 1D thermo-hydraulic lumped parameter model to simulate loop heat pipes as heat switches by regulating the temperature difference between the evaporator and the compensation chamber. The developed thermo-hydraulic model uses the continuity, energy, and momentum equations to represent the behaviour of loop heat pipes as heat switches. The model also highlights the importance of some thermal conductance parameters and correction coefficients for accurately simulating the different operational states of a loop heat pipe. The simulations are conducted using the proposed 1D model, solved through the application of the Mathcad block function. The numerical model presented is successfully validated by comparing the temperatures of the evaporator and condenser inlet nodes with those of a referenced loop heat pipe from the literature. In conclusion, in this research, the mathematical modelling of loop heat pipes as heat switches is presented. This is achieved by incorporating correction coefficients with Boolean logic that results in non-linear transient simulations. The presented 1D thermo-hydraulic lumped parameter model serves as a valuable tool for thermal system design, particularly for systems with non-linear operational modes like sorption compressors. The graphical and nodal representation of this proposed 1D thermo-hydraulic model further enhances its utility in understanding and optimising loop heat pipes as heat switches across various thermal management scenarios.
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
LA/P/0079/2020