Computational approach for investigation of thrust and acoustic performances of present-day nozzles

A computational viewpoint on the problems of design and numerical simulation for the nozzles of modern aircraft turbofan engines is presented. Modern concepts of noise-suppressing nozzles for civil aircraft are reviewed. Examples of application of CFD (computational fluid dynamics) methods to the analysis of nozzle flow structure and assessment of nozzle thrust characteristics are given. Errors of turbulence models in simulation of jets are analyzed. The authors’ experience in simulation of noise-suppressing nozzles for supersonic civil aircrafts is demonstrated. Insufficient accuracy of acoustic analogies for this class of tasks is shown, but a possible area of acoustic analogies application is noted. The essential elements of computational aeroacoustics (CAA) approach and numerical methods characteristic of CAA are reviewed. Numerical methodology for the simulation of nozzle acoustic performance is described in detail, including methods for simulation of near and far field of a nozzle, for generation of input perturbations and for the processing the far-field noise. Results of verification and methodical analysis of this acoustic methodology are presented.     

Computational tools for supporting the testing of civil aircraft configurations in wind tunnels

Following a review of well-known CFD packages, this paper presents the mathematical and methodical ideas, which became the basis of the numerical method for a solution of the Reynolds (time)-averaged Navier–Stokes equations (RANS), relevant to supporting testing an aircraft configuration in wind tunnels (WTs). The estimation of finite speed of information propagation due to diffusion is given. Explicit and implicit methods for numerical solution of gasdynamic equations are compared. Stability conditions, taking into account both interaction of convection with diffusion and presence of exponentially varying modes of solution, are considered. Three methods of time stepping organization are described—global, local and fractional time stepping. Numerical boundary conditions for simulation of flow in the WT are proposed. Examples of method implementation for the European Transonic Windtunnel (ETW) case are presented.     

Trajectory Control for a Spacecraft with an Inflatable Braking Device in the Martian Atmosphere

The possibility of using an inflatable braking device for controlled descent in the Martian atmosphere of large-capacity cargoes is analyzed. The most complicated version of the trajectory control problem is considered, namely, the injection of a spacecraft at hyperbolic velocity into a parking orbit after braking in the atmosphere.