Fernando Martini Catalano

Drag optimization for transport aircraft Mission Adaptive Wing

A direct optimization study was performed to produce a preliminary evaluation of the potential benefits of a mission adaptive wing employing variable camber technology in typical jet transport aircraft missions, in terms of fuel efficiency increase directly obtainable from airfoil viscous drag reduction alone. A 2-D airfoil analysis approach was adopted, associated with an idealized variable camber mechanism based on elastic deformation and surface extension. Using a direct function optimization program coupled to a viscous-inviscid airfoil analysis routine, optimized variable camber configurations were obtained for several weight conditions of a typical transport aircraft along a sub-critical cruise mission leg. Independent runs were executed considering only trailing and both leading and trailing-edge camber variation and, for each of them, an integrated range parameter has been obtained, proportional to the maximum possible aircraft range. Results indicate that the range increases up to 7.03% over the base airfoil that could be reached with camber variation in the trailing edge region only, and up to 24.6% when leading edge adaptation was considered simultaneously. However, pressure distribution results indicate that the high leading-edge curvatures required for that would probably decrease cruise critical Mach. On other hand, the trailing-edge only approach may offer better conditions for supercritical cruise.

Numerical study of synthetic jet actuator effects in boundary layers

This work has as a fundamental objective the numerical study of the effects of synthetic jet actuators on the flow of the boundary layer developed on a flat plate and on a hypothetical airfoil. The aim is to obtain computational data to indicate how these effects may be used as a means of flow control, describing the dynamics of the synthetic jet in the presence of external flow. The present paper uses a spatial Direct Numerical Simulation (DNS) to solve the incompressible Navier-Stokes equations, written in vorticity-velocity formulation. The spatial derivatives are discretized with a sixth order compact finite difference scheme. The Poisson equation for the normal velocity component is solved by an iterative Line Successive Over Relaxation Method and uses a multigrid Full Approximation Scheme to accelerate the convergence. The results of simulations with different values of frequency, amplitude and slot length were analyzed through a temporal Fourier analysis. Through this analysis the decision as to which are the better parameters to delay the separation of the boundary layer is examined.

Aerodynamic Analysis of High Rotation and Low Reynolds Number Propeller

An analysis of the accuracy of Vortex Theory of propellers to predict the characteristics of high rotation and low Reynolds number propellers is presented. Since the beginning of the nineteenth century, reliable basis theories have been applied on the aerodynamics analysis of full-scale propellers. However, the ever growing number of UAVs, most of them in smallscale for mapping and monitoring missions, demands new information on propeller behavior used on these aircrafts. The propellers involved must operate in a low Reynolds number, in the range of 60,000 to 160,000, and in a high rotation velocity, around 10,000 RPM. These features came from the small dimensions of the blades and the properties of the light engines, as two-stroke, Wankel and electric engines. The recognized Vortex Theory was employed to predict the aerodynamic characteristics of a 13-in diameter propeller and the results were compared with tests performed at the Engineering School of Sao Carlos, University of Sao Paulo. The maximum error in the prediction of the efficiency of the propeller was 8.8%. Therefore, the results indicate the limitations of the classical theories in the project of propellers for this regime, besides indicating regions where their applications is suitable.

Novel hybrid electric motor glider-quadrotor MAV for in-flight/V-STOL launching

This work presents a novel lightweight electric UAV that features fixed-wing motor glider aircraft and quadrotor helicopter capabilities. This paper presents the hybrid concept, design, evaluation and operation of a MAV (Mini Aerial Vehicle) named Sharky, fully designed and crafted by ART (Aerial Robots Team), which may be a versatile flying robot to broaden the scope of a great number of autonomous/tele-operated missions. To illustrate, Sharky may be potentially useful on precise positioning of sensors/equipment at any point in water/ground/air areas. The MAV may aid atmospheric sensing, water sample collecting, precise positioning of sensor for agriculture, surveillance of restricted/non-structured areas, such as post-disaster sites. The aircraft is morphologically and aerodynamically shaped to perform well defined and specific features, e.g., in-flight stable launching from a carrier, gliding ability, powered flight (motor-glider), transition between glider and quadrotor (and vice versa) and base level launching either as a quadrotor or a motor glider. Sharky transition (glider/quadrotor/glider) may be achieved at anytime during the mission. The aircraft center of mass is slightly shifted to offer gliding/motor gliding stability. Because it is a quadrotor, Sharky may either work as an inverted pendulum problem. Thus, translations and rotations are easily achieved using part of the potential energy from center of mass unbalance. Still, Sharky is easily able to return back to glider/motor glider configuration by using the same principle. That helps minimizing brushless motors usage and, therefore, battery consumption. Dynamic models are presented and analyzed. Sharky stability and controllability are first evaluated in VLM/Panels software. Secondly, wind tunnel analysis are run.

Experimental Aeroacoustic and Aerodynamic Analysis of a Large-scale Flap Side-edge Model

ACEVEDO, G. D. Experimental Aeroacoustic and Aerodynamic Analysis of a Large-Scale Flap Side-Edge Model. 2019. 142p. Dissertation (Master of Science) São Carlos School of Engineering, University of São Paulo, São Carlos, 2019. The first bypass turbofan engines came into operation in the early 1970’s. The need for reductions in the fuel consumption affected aircraft noise positively through reductions in the jet noise. Over the past decades, the bypass ratio of turbofan engines has continuously increased and, as a result, aircraft engine noise has decreased to a level comparable to the noise originated from the turbulent flow around the airframe for take-off and landing conditions. Although aircraft have become quieter, the number of individuals affected by the aviation growth is likely to increase. Airframe noise has been currently identified as the ultimate aircraft noise barrier and many efforts devoted to its reductions have focused specifically on landing gears and high-lift devices, which are the most relevant noise contributors. Some devices have been designed to reduce flap noise, however, not all of them have been successfully tested in a detailed large-scale flap model due to their difficult implementation in real flap side-edges. This research investigates the relationship between the parameters of a large-scale flap model at 1.50× 106 Reynolds number and the physics responsible for flap side-edge noise generation, one of the most dominant sources of the airframe noise. Experimental tests were conducted in a wind-tunnel and flow-field measurements were taken by a multi-hole pitot probe and an aerodynamic balance and complemented by phased microphone array techniques towards a deeper understanding of flap side-edge noise sources and their correlations to unsteady vorticity fluctuations. Conventional beamforming and CLEAN-SC and DAMAS deconvolution methodologies provided far-field acoustic spectra estimations and noise source mapping. The model used for the tests consists of an unswept isolated flap element with representative tip details present in conventional medium-range transport aircraft. The instrumentation includes 106 steady pressure taps distributed chord-wise and span-wise and a sand trip tape to transition the laminar boundary layer. Different side-edge devices were assessed towards airframe noise reductions. A perforated side-edge treatment was also applied to the flap side-edge. Results of aerodynamic and aeroacoustic tests conducted in the LAE-1 closed circuit wind tunnel with a closed test section at the São Carlos School of Engineering University of São Paulo (EESC-USP) at up to 40 m/s flow speeds provided specific information on the aeroacoustic and aerodynamic characterization of the dominant acoustic source mechanisms of the flap model.

Study on a Camber Adaptive Winglet

Morphing structures are devices intended to be implemented in specific parts of the aircraft such to improve some aspects of the flight such as performance and maneuverability. More specifically for the wings, the in flight capability of adaptation of airfoil profile and control surfaces bring possibility to the aircraft operate at optimum performance condition during all flight phases. Morphing structures can only lead to optimal flight maneuverability and performance conditions if the morphed geometry leads to an improved flight condition. Aiming at the reduction of the lift induced drag in all flight phases, this research focus on the application of the genetic optimization algorithm for the definition of the camber section of an winglet. This research proposes the optimization at four different flight phases namely: climb, heavy cruise, mid cruise and light cruise. BLWF – a full potential equation solver coupled with 3D boundary layer modelling – is adopted in the aerodynamic performance, e.g. lift and drag ratio, calculation. A conventional genetic algorithm is adopted in the optimization of the camber of the airfoil composing the winglet. This paper describes the optimization procedure and compares geometries showing that the in flight change of the winglet geometry can sensibly contribute to the improvement of the aircraft performance reducing the fuel consumption.

SquidCop: Design and evaluation of a novel quadrotor MAV for in-flight launching air-to-ground missions

Energy limitations play a major drawback in aerial robotics. Regarding the deployment of a MAV (Mini-Aerial-Vehicle), depending on the distance between base and robot, most of battery charge is simply wasted in the robot round trip. Non-structured or difficult-access locations may detract from the task or be unreachable to a flying robot in terms of energy capacity. In that sense, a novel category of MAVs that may be in-flight launched may broaden and optimize the scope and quality of several tasks not covered by current MAVs and UAVs (Unmanned Aerial Vehicle). The originality of this work is to introduce a specially shaped quadrotor named SquidCop, which may perform autonomous and stable in-flight launching from a carrier aircraft. SquidCop is a low scale MAV fully designed by ART (Aerial Robots Team), which is intended to broaden the scope and range of missions, indoor, outdoor or both together. SquidCop is aerodynamically designed to offer passive stability during release, free fall and positioning at a certain point in the space. Overall drag coefficient is carefully calculated to provide correct sink rate. Still, structural integrity is guaranteed from stress. Such features ensure correct attitude angle and minimum usage of reverse power from electric motors. Unlike regular missions where MAVs necessarily use battery power between the base and the point of interest, SquidCop is intended to use minimum battery charge at descent. Hence, more battery charge may be available to be used from the very moment when mission starts. Low-cost assembly is suitable for extreme missions that may potentially represent the complete loss of the equipment. Complete analysis involves modeling, CFD (Computational Fluid Dynamics) and wind tunnel evaluation.

The Influence of Demoiselle Aircraft on Light and General Aviation Design

In 1907, aviation pioneer Santos-Dumont had the idea of building a very light airplane. He designed and built the SD19, the Demoiselle, an aircraft with a 6 meter wing span and a 24 HP engine of his own design. The Demoiselle was very successful in flying and, became very popular and its development continued as SD20, SD21 and SD22 (his last airplane). The influence of the Demoiselle on design principles of light aircraft and general aviation were studied in this work, using statistical entropy. The designs number 20 and 22 may be considered dominant and influenced the design principles of light aircraft and general aviation.