Second Order Slip Flow And Heat Transfer Over A Stretching Sheet With Non-Linear Navier Boundary Condition

In this paper, we analyze the second order slip flow and heat transfer over a stretching sheet. The governing partial differential equations of the flow and heat transfer are reduced into non-linear ordinary differential equations. An exact solution for the momentum equation is obtained and the governing energy equation is solved numerically by a fourth order Runge-Kutta method with shooting technique. The effects of various physical parameters such as the mass transfer parameter s, the first order slip parameter γ and the second order slip parameter δ on the fluid flow are analyzed (through graphs). Also the effects of the above said parameters (s, γ, δ) and the Prandtl number Pr on heat transfer are investigated and discussed for two general heating conditions (i) prescribed surface temperature (PST case) and (ii) prescribed heat flux (PHF case). Furthermore, the numerical results for the wall temperature gradient (the Nusselt number) in PST case and wall temperature in PHF case are presented in a table and the salient features are discussed. © 2012 Elsevier Masson SAS. All rights reserved

Mhd Flow And Heat Transfer Over A Stretching Surface With Variable Thermal Conductivity And Partial Slip

In this paper we analyze the flow and heat transfer of an MHD fluid over an impermeable stretching surface with variable thermal conductivity and non-uniform heat source/sink in the presence of partial slip. The governing partial differential equations of the problem are reduced to nonlinear ordinary differential equations by using a similarity transformation. The temperature boundary conditions are assumed to be linear functions of the distance from the origin. Analytical solutions of the energy equations for Prescribed Surface Temperature (PST) and Prescribed Heat Flux (PHF) cases are obtained in terms of a hypergeometric function, without applying the boundary-layer approximation. The effects of the governing parameters on the flow and heat transfer fields are presented through tables and graphs, and they are discussed. Furthermore, the obtained numerical results for the skin friction, wall-temperature gradient and wall temperature are analyzed and compared with the available results in the literature for special cases. © 2012 Springer Science+Business Media Dordrecht

Numerical Simulation and Validation of the Aerodynamics of Static and Dynamic Spoilers

Spoilers play a vital role in the flight control systems of modern transport aircraft. Due to their efficiency and fast deflection rates they are widely used to assist in roll control or for gust load alleviation purposes. Simulating the aerodynamic behavior of spoilers still is a challenging task as deflecting a spoiler always induces flow separation. The work presented in this paper therefore focused on extending the application range of DLR’s in-house flow solver TAU by verifying and validating it for spoiler applications. In a first step, the work focused on steady and unsteady simulations of static and dynamic spoiler deflections in the low-speed regime. It was shown that the chosen numerical approach is well-suited to reproduce the surface pressure distribution for static spoiler deflections of up to 50°. Above that, the simulated transient aerodynamic response was found to be in good agreement with experimental data for a variety of deflection times and deflection angles

Towards the Investigation of Unsteady Spoiler Aerodynamics

Aircraft configurations with deployed control surfaces are increasingly in the limelight of aerodynamic investigations using high-fidelity based Computational Fluid Dynamics to possibly reduce the conservatism in the design process. So far, most applications Focus on static control surface deflections. To close the gap towards future simulations of entire flight maneuvers, including gust encounters, the dynamic motion of the control surfaces and their transient impact on the aircraft configuration need to be taken into account. Hence, extending the application range of its flow solver TAU is of strategic interest for the Institute of Aerodynamics and Flow Technology of the German Aerospace Center (DLR). To support these numerical activities DLR developed a wind tunnel model with an active spoiler. In collaboration with German-Dutch Wind Tunnels, the aerodynamic Performance of this model has been examined in two wind tunnel campaigns in 2016, focusing on static and dynamic spoiler deflections. The present paper gives an overview on the motivation of this work and highlights the experimental setup as well as exemplary results. The data will later be used to further validate the DLR flow solver TAU