Vol 61, No 1 (2018)

The calculation of the design parameters of lifting airscrew systems with fixed and tilted rotor, including the investigation of the operation schemes of actuators for the propeller control system, is carried out.

The possibility of constructing an optical scheme of a telescope for a small satellite based on mirrors with freeform surfaces and a curved photodetector is considered. It is shown that the use of a new element base allows the effective area of the main mirror to be maximized and the field of view up to 9.4 times to be increased in comparison with the classical scheme of the Ritchey–Chretien scheme in ensuring the high image quality.

Real values of parameters for a space vehicle and its steering devices are specified by using the motion parameters measured in flight based on solving the differential equations of motion.

This paper applies the Detached-Eddy Simulation (DES) method to resolve a larger part of the flow spectrum around rotor blades in hover and forward flight. A comparison between DES and Unsteady Reynolds–Averaged Navier–Stokes simulation was carried out for the case of a forward flying rotor suggesting that DES has great potential for rotor applications.

Active influence dimension of film cooling along the blade profile is investigated with using the Spalart–Allmaras turbulence model. The cooling effectiveness of vane platforms and vane fillets is studied with the use of perforation holes on the leading edge.

This paper presents the results of an investigation of ejectors with the low entrainment ratio. A technique for calculating the ejectors with a curvilinear axis has been developed. Comparative studies of the performance characteristics of ejectors with the rectilinear axis of the mixing chamber and the curvilinear initial section of the mixing chamber are carried out.

This paper demonstrates that in transition from the one-dimensional longitudinal-channel motion of the coolant in the regenerative cooling system of the liquid propellant engine to the twodimensional (interchannel) channel motion (transpiration) through a porous mesh material (PMM), the hydraulic losses decrease. Experimental data on PMM hydraulic resistance coefficients and heat transfer in porous paths with the interchannel coolant transpiration (ICCT) is presented.

A dimensionless system K was obtained to determine the concentration of nitric oxide in the addition of hydrogen to the air-fuel mixture by calculation. The model obtained was tested on the VAZ-1118 engine.

This paper considers an issue of increasing reliability of turboprop engine simulation on a semi-full-scale simulation test bench. A detailed mathematical model (subassembly model) of a turboprop engine is used for improving simulation quality and optimizing the algorithms of turboprop automatic control system in the operation conditions being expected.

Influence of stack structure on porosity of composite materials at different modes of autoclave molding was studied. To reduce porosity of composite materials, specific stack structure and molding mode are recommended.

Gas and powder flow structure in a four-jet nozzle of a laser cladding head was optimized using a shadow imaging device and high-speed tracer visualization. Experimental results show that an excessive protective gas flow rate can lead to the spatial defocusing of transport gas jets.

The paper considers the physical principles of operation, performance and structural diagram of the short base sonar navigation system installed aboard an amphibious unmanned aerial vehicle. This system provides the required course piloting in the seaplane basin that is assigned by the network system of bottom transmitter-receiver antenna assemblies.

This paper analyzes the possibility of increasing the spectral efficiency of phase radio-technical data transmission systems that operate under conditions of mutual interference of symbols when “transparency windows” are used. The conditions for emergency of “transparency windows” are defined, recommendations for their application with the purpose of increasing the spectral efficiency of communication systems being considered are presented. Changes in time characteristics of “transparency windows” are analyzed (their lengths over the range of channel symbol time duration) depending on the frequency detuning.

The scaling factors in the problems of assessing the resistance to high-speed impact of plates and shells are analytically determined. Numerical experimentation shows the possibility of applying certain scaling factors in assessing the impact resistance of laminated plates and shells from materials with orthotropic properties.

The problem of identifying rigidities in stiffeners of a four-stiffener torsion box operating in tension–compression under the action of an external load is considered. An iterative approach is proposed using a sensitivity function and a sensitivity matrix.