Guilherme Lara Oliveira

Grid Sensitivity Effects in Collection Efficiency Computation

The present work compares the effects on accuracy of different grid generation choices and practices with respect to collection efficiency calculation on a typical aircraft configuration. It is known that hexahedral mesh es provide more accurate and better representation of the surface gradients, but on the other hand, requires more expertise and effort. This paper compares hexahedral, tetrahedral and hybrid (tetra + prism) meshes with respect to collection. Results indica te that the impingement region limits are rather insensitive to mesh choice, but the maximum and averaged collection can vary significantly. Some general levels of equivalency are proposed based on the experiments performed for the DLR -F4 configuration.

Computational Study of Submerged Air Inlet Performance Improvement Using Vortex Generators

In this computational work, the influence of a delta wing vortex generator on the boundary layer that develops upstream of a submerged air intake is studied. The state-of-the-art analysis and design of these intakes is discussed in detail. The flow in a conventional NACA inlet is analyzed numerically and its results are considered as a reference for the cases in which the vortex generator is included. A delta wing vortex generator is designed and mounted to the conventional NACA inlet, and the result of this configuration is studied through parametric variations of the vortex generator geometry. Finally, a support mast of the vortex generator is designed and included in the model, and simulations are performed for the configuration NACA inlet with vortex generator and mast. Three sideslip angles are considered for the mast. The results show that the use of the delta wing vortex generator is responsible for considerable reductions of the boundary-layer thickness and, consequently, significant improvements of the performance parameters of the NACA inlet. The improvements relative to the conventional NACA intake in terms of ram-recovery ratio and mass flow rate are of up to 53 and 19%, respectively.

Study of the Influence of Aircraft Geometry on the Computed Flowfield During Thrust Reversers Operation

Computational Fluid Dynamics (CFD) evaluation of aircraft installed thrust reverser flows is a particularly challenging problem due to the inherent complexity of the phenomena involved in terms of engine/aircraft transients and geometric configuration. In this paper, the methodological approach to the use of CFD for the analysis and study of the airflow from a cascade thrust reverser in a regional jet is discussed. Three different landing configurations, representatives of a regional jet aircraft with wing-mounted engines and cascade-type thrust reverser were defined: (i) baseline geometry with clean wing configuration and without landing gears or spoilers; (ii) intermediate geometry containing the baseline with wingtips, flaps and slats deployed; (iii) a complete configuration which adds landing gears and spoilers to the intermediate geometry. The effects of the geometric configuration in the computed flowfield during thrust reverser operation were evaluated. A commercial CFD solver was used in the computations. The adequacy of solver parameters and turbulence models chosen for thrust reverser calculations were verified by comparing results from simulations with experimental results in a problem of a jet in a cross flow. Results indicate that a detailed modeling of the aircraft in landing configuration could be necessary, particularly for evaluation of exhaust flow re-ingestion by the engines and regions impinged by the reverser flow on the fuselage.

A Methodology for the Design of APU Air Inlets for Regional Commercial Aircraft

A methodology for the design of air inlets used in Auxiliary Power Units (APU) of regional commercial aircraft is described. Starting from the general requirements for the aircraft and the APU system the methodology is divided in steps of increasing complexity. In the preliminary design, it is defined the location and main geometrical parameters, based on semi-empirical methods. In a second phase 2D inlet profiles are generated and evaluated through CFD in terms of inlet pressure recovery and aerodynamics. In the last phase 3D CFD calculations area used to define parameters as inlet alignment with external flow and to check the 2D results. An application of the methodology in the design of APU inlets for a new tailcone project of the ERJ145 aircraft is presented.

Inverse aerodynamic design applications using the MGM hybrid formulation

The well-known modified Garabedian–Mcfadden (MGM) method is an attractive alternative for aerodynamic inverse design, for its simplicity and effectiveness (P. Garabedian and G. Mcfadden, Design of supercritical swept wings, AIAA J. 20(3) (1982), 289–291; J.B. Malone, J. Vadyak, and L.N. Sankar, Inverse aerodynamic design method for aircraft components, J. Aircraft 24(2) (1987), 8–9; Santos, A hybrid optimization method for aerodynamic design of lifting surfaces, PhD Thesis, Georgia Institute of Technology, 1993). Owing to these characteristics, the method has been the subject of several authors over the years (G.S. Dulikravich and D.P. Baker, Aerodynamic shape inverse design using a Fourier series method, in AIAA paper 99-0185, AIAA Aerospace Sciences Meeting, Reno, NV, January 1999; D.H. Silva and L.N. Sankar, An inverse method for the design of transonic wings, in 1992 Aerospace Design Conference, No. 92-1025 in proceedings, AIAA, Irvine, CA, February 1992, 1–11; W. Bartelheimer, An Improved Integral Equation Method for the Design of Transonic Airfoils and Wings, AIAA Inc., 1995). More recently, a hybrid formulation and a multi-point algorithm were developed on the basis of the original MGM. This article discusses applications of those latest developments for airfoil and wing design. The test cases focus on wing-body aerodynamic interference and shock wave removal applications. The DLR-F6 geometry is picked as the baseline for the analysis.

Conjugate Heat Transfer Methodology for Aircraft Pylon Analysis

EMBRAER’s new family of aircraft, the E170/E190 family, has its engines placed under the wing. This fact required a new process for pylon design when compared to the previous aircraft (the ERJ145) with the rear fuselage placed engine pylons. The new process had to take into account a much more severe thermal environment. This work presents the pylon analysis methodology based on CFD developed by EMBRAER. Applying this process thoroughly on the E170/E190 family pylon design allowed great savings in pylon weight at relatively short turnaround design time. The accuracy of the conjugate CFD simulations is evaluated by comparing the results for surface temperature on the pylon and internal systems with measured data gathered during flight test campaign.