In the context of ambitious targets for reducing environmental impact in the aviation sector, dictated by international institutions, morphing aircraft are expected to have potential for achieving ...the required efficiency increases. However, there are still open issues related to the design and implementation of deformable structures. In this paper, we compare three constrained parameterisation strategies for the aerodynamic design of a morphing leading edge, representing a potential substitute for traditional high-lift systems. In order to facilitate the structural design and promote the feasibility of solutions, we solve a multi-objective optimisation problem, including constraints on axial and bending strain introduced by morphing. A parameterisation method, inherently producing constant arc length curves, is employed in three variants, representing different morphing strategies which provide an increasing level of deformability, by allowing the lower edge of the flexible skin to slide and the gap formed with the fixed spar to be closed by a hatch. The results for the optimisation of a baseline airfoil show that the geometric constraints are effectively handled in the optimisation and the solutions are smooth, with a continuous variation along the Pareto frontier. The larger shape modification allowed by more flexible parameterisation variants enables an increase of the maximum lift coefficient up to 8.35%, and efficiency at 70% of stall incidence up to 4.26%.
Several passive and active techniques were studied and developed by compressor designers with the aim of improving the aerodynamic behavior of compressor blades by reducing, or even eliminating, flow ...separation. Fluidic-based methods, in particular, have been investigated for a long time, including both steady and unsteady suction, blowing and oscillating jets. Recently, synthetic jets (zero mass flux) have been proposed as a promising solution to reduce low-momentum fluid regions inside turbomachines. Synthetic jets, with the characteristics of zero net mass flux and non-zero momentum flux, do not require a complex system of pumps and pipes. They could be very efficient because at the suction part of the cycle the low-momentum fluid is sucked into the device, whereas in the blowing part a high-momentum jet accelerates it. To the authors’ knowledge, the use of synthetic jets has never been experimented in transonic compressor rotors, where this technique could be helpful (i) to reduce the thickness and instability of blade suction side boundary layer after the interaction with the shock, and (ii) to delay the arising of the low-momentum region which can take place from the shock-tip clearance vortex interaction at low flow operating conditions, a flow feature which is considered harmful to rotor stability. Therefore, synthetic jets could be helpful to improve both efficiency and stall margin in transonic compressor rotors. In this paper, an accurate and validated CFD model is used to simulate the aerodynamic behavior of a transonic compressor rotor with and without synthetic jets. Four technical solutions were evaluated, different for jet position and velocity, and one was investigated in detail.
In this paper, a fast and effective CFD-based automatic loop for optimization of rotorcraft components is presented. The automatic loop is strictly designed around an innovative Multi Objective ...Evolutionary Algorithm (MOEA) developed at University of Padua, namely the GeDEA-II. This algorithm allows performing multi-objective, multi-point optimization works in a fast and robust way. It combines novel crossover and mutation operators when compared to other state-of-the-art MOEA. Recent papers show its excellent performance when tested on state-of-the-art problems. In order to test the performance of this algorithm, two test cases are presented, each having peculiar characteristics making them even harder to solve. Test cases regard the aerodynamic shape optimization of ERICA components, that is an innovative tilt-rotor concept conceived and designed recently. The first problem regards the single-objective, multi-constrained aerodynamic optimization of the ERICA tilt-rotor cockpit region. The second one is a multi-objective multi-constrained optimization of the ERICA landing gear sponsons. Results demonstrate the effectiveness of this automatic optimization loop in tackling real-world engineering problems.
The present work aims at introducing a fast and effective CFD-based automatic loop for optimization of rotorcraft components. The automatic loop presented here was strictly designed around an ...innovative Multi Objective Evolutionary Algorithm, developed at University of Padua, namely the GeDEA-II. Recent papers showed its excellent performance when tested on state-of-the-art problems. In order to test the performance of this algorithm two test cases are presented, each having its peculiar characteristics. The first problem regards the single-objective, multi-constraints aerodynamic optimization of the ERICA tilt-rotor cockpit region. The second one is a multi-point multi-constraint optimization of the left intake of the AgustaWestland AW101 helicopter. Results demonstrate the effectiveness of this automatic optimization loop in tackling real-word engineering problems.
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