Vol 20, No 2 (2021)

Derivation of analytic expressions making up the basis of a mathematical model of aircraft flight dynamics for the differential equations describing the change in the rate of roll, yaw and pitch, as well as flight velocity components in projections on the body-fixed coordinate axes is presented. The origin of the coordinate system does not in general coincide with the center of mass of the plane, and the axes are not the same as its main central axes of inertia. The differential equations for angular and linear velocities are reduced to the form convenient for the use of numerical methods and computer systems and make it possible  to get consistent results of simulating the dynamics of aircraft spatial motion with an arbitrary tensor of inertia and center of gravity position.

The article discusses the issue of automating the serial process of bleeding and control of the pitot- static system of passenger airplanes. A functional diagram and basic design of some parts of the combined equipment are proposed. This equipment makes it possible to alternate the above-mentioned operations with great effectiveness. At the system control stage, the pressure or vacuum in it is created by a pressure-vacuum pneumatic unit. This pneumatic unit consists of a compressor and a set of electromagnetic valves that allow the compressor to be connected to the pumping or scavenging line. The value of the generated pressure is regulated by the flow rate in the pressure/scavenging channel and in the venting channel. Simulation of changes in ambient temperature is achieved due to blowing heated or cooled air over the temperature sensors of the aircraft. Pressure or vacuum in the controlled system is created in turn, in each of its lines. At the expulsion stage, a compressed-nitrogen cylinder acts as the pressure source. The pressurized gas passes through the pitot and is released into the atmosphere, cleaning out the contaminations. No manual operations are required for installing and removing connection hoses after connecting the proposed combined equipment to the pitot-static system. Remote-controlled electromagnetic valves connect the channels of the controlled system to the pressure-vacuum pneumatic unit and the source of compressed nitrogen. This reduces the duration of successive operations for the system’s maintenance.

When solving the problem of reducing the acoustic load on the spacecraft during the launch and flight of the launch vehicle, finite element modeling of acoustic processes under the nose fairing is carried out. To successfully solve this problem, a mathematical model of the acoustic characteristics of the material used for sound insulation is required. The existing mathematical models of the acoustic characteristics of materials are not suitable for the material under consideration that can be used in rocket and space technology to increase the sound insulation of the payload fairing + transfer compartment assembly. To obtain the sound absorption coefficient of the material, an impedance tube measurement method with two microphones is used. Using the method of differential evolution, the coefficients of a mathematical model of acoustic characteristics of the Delany-Bazley type for the specified material are selected. The sound absorption coefficient obtained experimentally and that calculated using the obtained model are compared; the average and maximum values of the error are shown. The resulting model will make it possible to carry out finite element modeling of acoustic and vibroacoustic processes under the nose fairing, taking into account the location of the sound-absorbing material.

The thermal fields of the “Photon-Amur 2.0” payload electronic board developed for nanosatellites were studied. The “Photon-Amur 2.0” payload consists of an electronic control board with a casing mounted in a nanosatellite and a remote panel with experimental photovoltaic converters. A modified heat balance method was used for numerical simulation of the thermal fields of the control board and the casing. The constructed model and the obtained results of the numerical simulation were verified by comparison with the thermal diagrams obtained for the “Photon-Amur 2.0” electronic board under normal operating conditions. For modeling the outer space operating conditions, it was assumed that there is a vacuum outside and inside the “Photon-Amur 2.0” casing, and the thermal effect is transmitted from the nanosatellite racks to the payload electronic board through the fastenings. The thermal effect is of a periodic nature with amplitude of –45 to +80^○C and a period of 96 min, which approximately corresponds to the motion of a nanosatellite in a 575 km-high orbit. It was demonstrated that with such composition of the payload module, its casing can work as a passive thermoregulator of thermal fields on the electronic board of “Photon-Amur 2.0”. The simulation showed that the casing helps to keep the temperature on the control board in the interval of –15°C to +85°C, which is acceptable for the electronic components used on the payload control board.

The existing methods for calculating the assembly dimensional chains of aircraft engine rotors are analyzed. The factors that have a significant impact on the reliability of the calculation of the controlled assembly parameters of the product are identified. One of these factors is the existence of parallel connections of parts in the rotor. In the drum & disk rotors, parallel rotor connections are formed by mating their parts along several end surfaces in the axial direction. A mathematical model is proposed that allows taking into account the parallel connections of the rotor parts. The form of relationship between rotor end run-outs and amplitudes of deviations of the shape of the mating surfaces of the parts and their angular positions in the unit is determined. The determined dependence includes many coefficients that allow taking into account the amplitudes of deviations of the shape of the mating surfaces, parallel connections of parts in the rotor, and their angular position. Determination of dependence coefficients’ values is solved as a problem of regression analysis. The initial data for obtaining the dependence are formed using the developed parameterized finite element model (FEM) of a part of the rotor of an aircraft engine high-pressure compressor (HPC). The results of research of end run-outs of control surfaces of disks of the considered HPC rotor assembly part are presented. The values of the dependence coefficients for assessing the end run-outs of the rotor are determined.

The article is prepared for the centenary of the birth of Alexander Petrovich Merkulov. The stages of creating the theoretical basis of the vortex effect of energy separation of gases (the hypothesis of vortex interaction), and the creation and implementation of vortex devices based on the use of the vortex effect for aviation and medicine are considered. The role of Professor A.P. Merkulov in the study of characteristic features of the energy separation process in vortex tubes and practical application of the vortex effect in the USSR is shown. The works of ONIL-9 (KuAI-SGAU) headed by Alexander Petrovich Merkulov ensured the leading position of the Soviet school of thought in the field of vortex effect. These works contributed to the formation of modern understanding of the vortex effect and the successful beginning of industrial application of vortex apparatuses.