Roberto da Mota Girardi

WING STRUCTURAL WEIGHT EVOLUTION WITH THE CRUISE MACH NUMBER OF A COMMERCIAL TRANSPORT AIRCRAFT

The present work performs a detailed analysis of the impact of the cruise speed of a commercial twinjet transport aircraft on its wing structural weight. The results will provide designers some guidelines for conceptual studies, when a cruise speed must be then specified. Some assumptions were made in order to conduct the proposed analysis: the fuel shall be store d in the wings only; the same fuselage was considered for all configurations, regardless of their cruise speed; and a maximum range of 3,695 nm (6,843 km). An algorithm named Asa Turbo was developed for the estimation of the initial wing configuration. By fulfilling design requirements and employing a performance calculation code, the procedure is able to calculate the corresponding lift coefficient and wing geometry parameters such as sweep angle, area, and airfoil maximum thickness, additionally providing an initial estimation for the wing structural weight according to the Torenbeek’s method. In order to better calculate the wing structural weight, a framework for wing structure preliminary design was employed. A code developed as PDWSW, which stands for Pre-Design Wing Structural Weight, was conceived to satisfy structural constraints as well as design requirements, based on load envelops and stress analyses under a Knowledge Based Engineering (KBE) environment. PDWSW outputs a minimum-weight structural configuration for a given wing planform. In order to start the weight estimation procedure, the wing conceptual -design Asa Turbo generated ten wing geometries for different cruise Mach numbers, ranging from Mach 0.75 to 0.90. All these wings were then modeled with CATIA ® and their structural design was considerably refined with the PDWSW framework. In order to utilize PDWSW, the user must define the position of the spars, ribs, and stringers and provide all preliminary dimensions of wings structure elements to obtain the minimum weight, within the required boundary safety. The numerical procedure implemented obtains the optimal number of ribs per wing box (main and trailing), the optimal number of stringers per rib bay, and optimal sizing of all structural components (skin, spars, ribs and stringers). This procedure guarantees that acceptable margins of safety and functionality requirements are fulfilled. The automation of the process is important in this particular application considering the enormous amount of data to be handled in a short period of time.

Wing Planform Optimization of a Transport Aircraft

The present work deals with multi-disciplinary design and optimization (MDO) of a transport aircraft wing. The aircraft must fulfil a given mission requirements under restrictions imposed by different aeronautical disciplines. The mathematical model of the MDO framework includes the calculation of aircraft drag polar (based on geometrical characteristics), engine trust, aircraft structural weight, volume available for fuel tank (which is stored only in the wings), stability derivatives, and performance for some flight phases. MATLAB was used then to implement build the related computational routines. Some design tasks for a twinjet aircraft, carrying eight passengers and a crew of three, were carried out for some specified maximum ranges and the results are analyzed here. 22nd Applied Aerodynamics Conference and Exhibit 16-19 August 2004, Providence, Rhode Island AIAA 2004-5191 Copyright

STUDIES USING WIND TUNNEL TO SIMULATE THE ATMOSPHERIC BOUNDARY LAYER AT THE ALCÂNTARA SPACE CENTER. doi:10.5028/jatm.2009.01019198

The Alcântara Space Center (ASC) region has a peculiar topography due to the existence of a coastal cliff, which modifies the atmospheric boundary layer characteristic in a way that can affect rocket launching operations. Wind tunnel measurements can be an important tool for the understanding of turbulence and wind flow pattern characteristics in the ASC neighborhood, along with computational fluid dynamics and observational data. The purpose of this paper is to describe wind tunnel experiments that have been carried out by researchers from the Brazilian Institutions IAE, ITA and INPE. The technologies of Hot-Wire Anemometer and Particle Image Velocimetry (PIV) have been used in these measurements, in order to obtain information about wind flow patterns as velocity fields and vorticity. The wind tunnel measurements are described and the results obtained are presented.

UTILIZAÇÃO DE TÚNEL DE VENTO PARA ESTUDOS DE DISPERSÃO HORIZONTAL DO ESCOAMENTO ATMOSFÉRICO NO CENTRO DE LANÇAMENTO DE ALCÂNTARA (CLA)

Utilizacao de tunel de vento para estudos de dispersaohorizontal do escoamento atmosferico no Centro deLancamento de Alcântara (CLA)

Effect of Tangential Blowing on Two Dimensional Boundary Layer of a Wind Tunnel

This paper reports an experimental effort to investigate the influence high-pressure air jet on the boundary-layer of the research low–speed wind tunnel of the Instituto Tecnologico de Aeronautica (ITA). Boundary layer control is very important in two-dimensional airfoil model tests. This may be done by either suction or blowing of the boundary layer. At ITA it was decided to blow high energy air into the test section. The literature reports that tunnel wall boundary-layer control, at the wall-model junctions, is necessary in order to obtain useful results from two-dimensional high-lift tests in wind tunnels. Here, it is shown results of the interaction of several configurations of the air jet with the wind tunnel boundary layer. Three injector thicknesses were used 1.0 mm, 1.5 mm and 2.0 mm. The angle was either of 10 o or 20 o . Boundary layer measurements were obtained using a pressure rake. It was positioned at eight stations along the test section, X1=10 cm, X2=16 cm, X3 =22 cm, X4= 28 cm, X5= 34 cm, X6= 40 cm, X7= 50 cm e X8= 60 cm measured from blower slot. The free stream dynamic pressure was kept constant, q∞ = 325 mmH2O.

Wind Tunnel Test of a Three-Element Airfoil Configuration: Development of Experimental Apparatus and Procedure Required for Obtaining Reliable Results

In order to minimize the three dimensional flow on a two dimensional model placed inside a wind tunnel, blowers are installed at the wind tunnel walls where the model extremities are fixed. The basic idea is to increase the momentum of the wind tunnel boundary layer and avoid migration of fluid particles from the wind tunnel surface to the upper surface of a two dimensional model. With such kind of procedure the flow along the model span is minimized and true two dimensional characteristics can be obtained. The objective of the present paper is to describe the experimental apparatus designed and installed in the new wind tunnel of the Technological Institute of Aeronautics (ITA), which has been used to develop a new experimental procedure for obtaining a true two dimensional flow over a three element airfoil, used in the EMBRAER 170. The second objective of the present paper is to report the results of the initial experiments, which were conducted to determine the data acquisition system parameters required to obtain accurate results for the average pressure coefficient. Other detail investigated during this research was the influence of the flow originated at the blower on the dynamic pressure of the wind tunnel. All the effort performed by the authors is correlated to a great research line, whose objective is to develop experimental procedures for obtained reliable results.