Este trabalho apresenta uma metodologia para a extensão do Método da Rede Turbilhonar Generalizado na obtenção da evolução temporal dos coeficientes de força e momento aerodinâmicos em regime de vôo supersônico não estacionário. É utilizado um modelo linearizado das equações básicas da mecânica dos fluidos para a obtenção da resposta indicial de asas planas e sem espessura. Os resultados são comparados aos existentes na literatura, obtidos por meio de cálculos analíticos, demonstrando a validade do método. São estudadas as influências das características geométricas da asa e do número de Mach na resposta aerodinâmica a uma variação em degrau de ângulo de ataque. Devido à linearidade do modelo, os resultados obtidos podem ser utilizados na obtenção da resposta a um movimento qualquer, por meio do princípio da superposição e da aplicação da integral de Duhamel.

Unsteady phenomena like flutter, buffeting, rapid maneuvers in flight and gust entry are usually modeled and studied by a theoretical treatment involving potential flow methods. The resulting equation from this approach is the governing differential equation for general non-steady, non-viscous, potential flow known as convected wave equation. The disturbance, represented in this equation by the velocity potential, is propagated as wave which spreads at a rate equal to the local speed of sound. Linearization on the basis of small disturbances in a uniform stream of compressible fluid is made upon the equation by the procedure of retaining first order terms. Elementary solutions for this simplified equation recognized as primary extension of the concepts of source, sink, vortex and doublet, used together with boundary conditions associated with the governing equation, enables proper treatment for understanding and tackling non-steady aerodynamic problems. This thesis presents a numerical solution for the aerodynamics lift coefficient of a thin airfoil in arbitrary motion in a uniform, compressible, subsonic flow field. Distribution of vortex type elementary solutions of the convected wave equation is used together with a time function that schedules the vortex strength in time to represent in effect the arbitrary vortex moving along a chosen path. A field point is then influenced by the continuous disturbances generated by the vortex with a delay relative to the time of action of the same vortex. A fixed coordinate system in space relative to the body is chosen. So the body is fixed in a moving flow. The analytical vortex solution is presented together with the appropriate transformation variables needed to treat the problem.

Unsteady solutions for the aerodynamic coefficients of a thin airfoil in compressible subsonic or supersonic flows are studied. The lift, the pitch moment, and pressure coefficients are obtained numerically for the following motions: the indicial response (unit step function) of the airfoil, i.e., a sudden change in the angle of attack; a thin airfoil penetrating into a sharp edge gust (for several gust speed ratios); a thin airfoil penetrating into a one-minus-cosine gust and sinusoidal gust (a typical gust used in commercial aircraft design); oscillating airfoil; and also the interaction of the airfoil with a shed (from convection phenomenon) vortex passing under the airfoil, a phenomenon known in literature as AVI (Airfoil Vortex Interaction). The present work uses a numerical approach based on vortex singularity. The numerical model is created by means of the airfoil discretization in uniform segments and the compressible flow vortex singularity is used. The results available in the literature are based on approximated exponential equations, or computed via Computational Fluid Dynamics (CFD). Thus, the purpose of this method is to obtain a more accurate computation compared to those of approximated equations, and numerically quite faster compared to those obtained via CFD.

This work presents a study on aeroelastic analyses of composite laminated flat plates subject to large displacements through the coupling of a nonlinear corotational shell finite element (FE) with an unsteady vortex-lattice method (UVLM) formulation. A FE implemented for the analysis of flat plates has been extended to model laminated composites with different lamina orientations. An UVLM formulation that is capable of coupling with this large displacement structural model is implemented. An explicit partitioned method is evaluated for the coupling of both models, using spline functions to interpolate information from the structural operator to the aerodynamic one, inside a Generalized-? time-marching solution. The resulting aeroelastic formulation provides a framework able of performing time marching simulation of structures made of composite material allowing the characterization of their nonlinear behavior and of the limit-cycle oscillation response. Laminated flat plates designed for high flexibility and low flutter speed onset are used as investigation models. To support the numerical studies, test specimens made of carbon fiber were used in experimental modal analysis and wind tunnel aeroelastic tests. Effects of nonlinearities are easily observed in the numerical results, which are promising for expansion of the work and application to the analysis of more refined and complex composite flexible wings.

O processo de injeção de combustíveis nas câmaras de combustão é de vital importância, sob diversos aspectos, para o funcionamento ideal de cada tipo de motor. O elemento responsável pela introdução de propelentes líquidos e gasosos na câmara de combustão de foguetes e pela transformação de massas líquidas em "sprays" é o injetor que converte a energia potencial dos propelentes em energia cinética, pela queda de pressão em seu interior, formando um jato ou folha líquida que se desintegra então em gotas[

Presented here is the effort concerning the application of Computational Fluid Dynamics (CFD) as a swirl injector analysis tool. A literature review of the major inviscid swirl models is provided along with the viscous correction procedure. The bi-propellant atomizer design process is described and the features of previous designs are also detailed. The study was undertaken by focusing on the 5-[kN]-thrust rocket engine currently in development. Theoretical predictions of the discharge coefficient, spray angle and liquid film thickness were obtained for both the inner and outer swirlers of the core injection elements. The governing equations are solved based on the laminar volume of fluid (VOF) interface capturing method. Results from cold flow experiments and particle image velocimetry (PIV) are compared to the predictions of the swirl models and the numerical results. The laminar VOF model was able to predict the spray angle with reasonable confidence, however, a deviation of 25 % was observed in the mass flow rate and discharge coefficient. Although the laminar VOF model has proven inadequate, it constitutes a good starting point in the procedure needed to assess swirl injector performance.