Analysis of stress state in a root-airfoil transition zone of hollow wide chord fan blades

In this paper, under consideration is the complex approach to analyzing the operation of a simulator for the hollow blade made from the VT6 titanium alloy. The stress state parameters in the hollow-monolithic part transition zone of the cantilevered simulator at bending under the distributed load are determined.     

Antenna systems of radio equipment for advanced UAVs: Problems and lines of development

The paper deals with the problem of creating airborne antenna systems for advanced unmanned aerial vehicles (UAVs). The ways of solving the basic problems, based on a combination of empirical approaches, electrodynamic simulation, and experimental results are proposed.     

Experimental study of pressure fields in a multilobe journal bearing

An experimental pressure field in operating clearance and flowrate parameters analysis for different eccentricities, inlet oil pressures, and journal rotating velocities are presented for a radial multilobe journal bearing. Lubricating film breakdown zones in bearing oil ducts caused by complicated construction and journal rotation are observed.     

Validation of numerical prediction of dynamic derivatives: The DLR-F12 and the Transcruiser test cases

The dynamic derivatives are widely used in linear aerodynamic models in order to determine the flying qualities of an aircraft: the ability to predict them reliably, quickly and sufficiently early in the design process is vital in order to avoid late and costly component redesigns. This paper describes experimental and computational research dealing with the determination of dynamic derivatives carried out within the FP6 European project SimSAC. Numerical and experimental results are compared for two aircraft configurations: a generic civil transport aircraft, wing-fuselage-tail configuration called the DLR-F12 and a generic Transonic CRuiser, which is a canard configuration. Static and dynamic wind tunnel tests have been carried out for both configurations and are briefly described within this paper. The data generated for both the DLR-F12 and TCR configurations include force and pressure coefficients obtained during small amplitude pitch, roll and yaw oscillations while the data for the TCR configuration also include large amplitude oscillations, in order to investigate the dynamic effects on nonlinear aerodynamic characteristics. In addition, dynamic derivatives have been determined for both configurations with a large panel of tools, from linear aerodynamic (Vortex Lattice Methods) to CFD. This work confirms that an increase in fidelity level enables the dynamic derivatives to be calculated more accurately. Linear aerodynamics tools are shown to give satisfactory results but are very sensitive to the geometry/mesh input data. Although all the quasi-steady CFD approaches give comparable results (robustness) for steady dynamic derivatives, they do not allow the prediction of unsteady components for the dynamic derivatives (angular derivatives with respect to time): this can be done with either a fully unsteady approach i.e. with a time-marching scheme or with frequency domain solvers, both of which provide comparable results for the DLR-F12 test case. As far as the canard configuration is concerned, strong limitations for the linear aerodynamic tools are observed. A key aspect of this work are the acceleration techniques developed for CFD methods, which allow the computational time to be dramatically reduced while providing comparable results.     

Formation of required transfer zero location in the multiconnected dynamic system

A method for providing the required location of a transfer zero set in the linear multiconnected dynamic system with an equal number of inputs and outputs is considered.     

Experimental study of strain for plates discretely connected to a cylindrical shell

We present the results of an experimental study of deflections for the loaded plates that are discretely connected to a circular cylindrical shell along the generatrix lines. The influence of structure element connection elasticity on these deflections has been examined. The unique experimental setup and three specimens being tested are described. Satisfactory agreement is shown between the experimental results and the calculation data obtained by the simplified mechanical model of a plane problem.     

Control of spacecraft turns in scheduled time using rocket engines

We obtained an on-off control law for two spacecraft (SC) rocket engines creating the angular acceleration in the opposite directions considering that SC is controlled by the rocket engines with an exponential increase of thrust at starting and decrease at shutdown. This control law provides the change-over of SC from the initial angular position to the final one in the scheduled time. A special trajectory consisting of eight typical segments is proposed to identify the angular acceleration and delay of its formation in the rocket engines. Both problems are solved by the method of analytical construction of composite trajectories for the angular turn from the typical segments on which the differential equations of angular motion have analytical solutions. The results are applicable for the development of promising space interceptors and design of onboard control systems.     

Divergence of a plate discretely supported by the stringer system

An approximate solution of the divergence problem, that is, of the static instability of a plate discretely supported by a system of stiffening ribs (stringers) in the gas flow. The critical velocity of divergence is determined in one-term approximation and the influence of stringers on it is analyzed.     

Construction of an airfoil with an irregularity in the flow

Using the method of quasisolutions for inverse boundary-value problems of aerohydrodynamics, a problem of constructing an airfoil was solved by the specified velocity distribution along the sought airfoil contour when there is an irregularity in the flow such as a vorticity source. The cases of a source (sink) and vortex are obtained as particular ones. The airfoils are constructed numerically and analytically and conclusions are made about an influence of the irregularity position and type on the shape and aerodynamic characteristics of the airfoil.     

Analysis of chaotic vibrations for the distributed systems in the form of the Bernoulli-Euler beams using the wavelet transform

A problem on chaotic vibrations of the Bernoulli-Euler beams is formulated. The wavelet transform was first applied to investigate the complex beam vibrations. The validity of results was provided by using two methods of solution, namely, the finite element method and finite difference method.