Swedish Defence Research Agency

About: Swedish Defence Research Agency is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Radar & Laser. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

A computational study of supersonic combustion behind a wedge-shaped flameholder

Abstract: In this study, large eddy simulation (LES) has been used to examine supersonic flow, mixing, self-ignition and combustion in a model scramjet combustor and has been compared against the experimental data. The LES model is based on an unstructured finite-volume discretization, using monotonicity-preserving flux reconstruction of the filtered mass, momentum, species and energy equations. Both a two-step and a seven-step hydrogen–air mechanism are used to describe the chemical reactions. Additional comparisons are made with results from a previously presented flamelet model. The subgrid flow terms are modeled using a mixed model, whereas the subgrid turbulence–chemistry interaction terms are modeled using the partially stirred reactor model. Simulations are carried out on a scramjet model experimentally studied at Deutsches Zentrum fur Luft- und Raumfahrt consisting of a one-sided divergent channel with a wedge-shaped flame holder at the base of which hydrogen is injected. The LES predictions are compared with experimental data for velocity, temperature, wall pressure at different cross sections as well as schlieren images, showing good agreement for both first- and second-order statistics. In addition, the LES results are used to illustrate and explain the intrinsic flow, and mixing and combustion features of this combustor.

A realistic military scenario and emulation environment for experimenting with tactical communications and heterogeneous networks

Abstract: Emulation environments are an effective approach to experimenting with and evaluating network protocols, algorithms, and components. This paper describes a joint effort by the NATO Science & Technology Organization's IST-124 task group to develop and distribute an emulation environment and scenario. The most significant contribution is a vetted and militarily-realistic scenario that provides a rich combination of elements for experimentation. The scenario includes detailed mobility patterns for a battalion-sized operation over the course of two hours, which has been developed by military experts in planning and performing real exercises. The mobility patterns are used to drive the network emulation.