TRANSPORTATION SYSTEMS
At the present stage of the development of aviation activity, there is a significant increase in aviation traffic, which in turn puts a significant burden on the supply of jet fuel to civil aviation. On average, 10.9 million tons of aviation kerosene per year are supplied to the domestic market of the country1. In Russia, a significant market share in the supply of aviation fuel is occupied by the leaders, among which now are Lukoil, Rosneft and Gazprom which all together are vertically integrated oil companies (VIOC). Along with the colossal volumes of production and supply of jet fuel, which include many technological operations, starting from the production stage to the direct delivery “to the wing” of the aircraft, the probability of production and supply of not only high quality, but also substandard jet fuel increases. Substandard fuel poses a rather serious threat during the operation of aviation equipment, being one of the many factors leading to failures of aviation equipment, aviation accidents and incidents, thereby reducing the level of flight safety. Oil refining companies, refueling complexes and airlines are interested in the safety of their activities, which have reliable systems and means to ensure it, but nevertheless substandard fuel takes place. One of the important reasons is the lack of a unified integrated flight safety system in terms of aviation fuel supply for air transportation, and therefore, it is necessary to search for new or implement existing adapted methods, solutions, systems and means to ensure the required level of flight safety.
The nature of the causes of prerequisites for flight accidents due to meteorological conditions has remained unchanged for many years. For the effective operation of aviation, it is necessary to solve the issues of the timely detection of weather hazards and the identification of their intensity. This article discusses the research into the atmospheric reflectivity and turbulence in cumulonimbus clouds using a near-field meteorological radar system. Experimental studies are carried out with the aim of obtaining estimates of statistical characteristics of the reflectivity distribution and turbulence for weather hazards. The methodology for conducting an experimental study to obtain information about the weather hazards (rain shower, thunderstorm and hail), special features of the radar reflectivity propagation and the specific rate of turbulent energy dissipation in the considered conditions for the Tver region is presented. The analysis of the obtained results has been carried out: comparisons of meteorological data derived, using the meteorological radar complex of the near airfield zone (WR BZ), with the reliable sources of meteorological observation data obtained during experimental studies. Studies of horizontal sections and vertical profiles of the weather hazards parameters under consideration, associated with the cumulonimbus area, have been carried out. A data bank has been formed. Histograms of the information parameter distribution have been constructed. The article considers the results of experimental data approximation, using the χ2 criterion for various distribution laws. It is shown that the distributions of reflectivity and turbulence can be described by the generalized Rice’s law. The results obtained can be used to correct the classification criteria of weather hazards to subsequently increase the justification and reliability of the weather hazard classification. The further development of the method to process meteorological information is also of paramount importance to more correctly interpretate experimental data processing results of remote meteorological phenomena sensing.
In May 2022, Saudi Arabian Military Industries, a Saudi government agency, acquired an augmented reality training platform for pilots. In September, the Boeing Corporation began the development of an augmented reality pilot simulator. In November, a similar project was launched by BAE Systems, a leading British developer of aeronautical engineering. These facts allow us to confidently speak about the beginning of a new era of aviation simulators – simulators using the augmented reality technology. One of the promising advantages of this technology is the ability to safely simulate dangerous situations in the real world. A necessary condition for using this advantage is to ensure the visual coherence of augmented reality scenes: virtual objects must be indistinguishable from real ones. All the global IT leaders consider augmented reality as the subsequent surge of radical changes in digital electronics, so visual coherence is becoming a key issue for the future of IT, and in aerospace applications, visual coherence has already acquired practical significance. The Russian Federation lags far behind in studying the problems of visual coherence in general and for augmented reality flight simulators in particular: at the time of publication the authors managed to find only two papers on the subject in the Russian research space, while abroad their number is already approximately a thousand. The purpose of this review article is to create conditions for solving the problem. Visual coherence depends on many factors: lighting, color tone, shadows from virtual objects on real ones, mutual reflections, textures of virtual surfaces, optical aberrations, convergence and accommodation, etc. The article reviews the publications devoted to methods for assessing the conditions of illumination and color tone of a real scene and transferring them to virtual objects using various probes and by individual images, as well as by rendering virtual objects in augmented reality scenes, using neural networks.
Training pilots of latest-generation aircraft to interact with other crews in flight is complicated by the high level of cockpit automation and information overload of crews, on the one hand, and by the responsibility of pilots for decisions made regarding air traffic, on the other hand. Since the unified methodology for training pilots to interact with other crews in the same airspace is not available, the development of qualitative training is required. To address this issue, a method, based on a preliminary calculation of the amount of information which is necessary to process by a pilot when training depending on the type of this information for the efficient formation of a conceptual model of air traffic in flight, has been developed. The method of forming a conceptual model of air traffic is based on the application of a mathematical model of “random walk with absorption”. The method consists of three phases. In the first flight phase, a pilot should operate a training flight en route. In the first flight of the second training phase, a trainee evaluates the tendency for the approach (separation) of the assessed aircraft to the trainee aircraft. In the second flight of the second phase, the assessed aircraft position is determined by the crew position and altitude reports, in the third flight – by the crew position, heading and altitude reports. In the third training phase, when operating three flights primarily en route, a trainee is supposed to evaluate the air situation according to all the parameters reported by crews operating in the same airspace. After flights of the second and third training phases, the pilot is meant to analyze and evaluate the air situation while operating a flight comprehensively by the number of aircraft in the flight area, their position and the sequence of their motion. The experimental results made it possible to determine that participants in the experimental group were 24% more efficient in evaluating the air situation and interacting with other crews in flight in the same flight area compared to the control group pilots. Processing of the experimental results showed that when employing the proposed training method, the reliability of the latest-generation aircraft crew interaction at the automatic piloting mode was statistically significantly increased.
Huge territories of the Russian Federation are occupied by permafrost. Often aviation is the only mode of transport that connects remote north areas of the country with the rest of Russia. The main feature of permafrost regions is the harsh climate, which includes low negative temperatures, an abundance of snow and strong winds. Such conditions make it extremely difficult to operate ground vehicles that service and maintain flights. In recent years, more and more domestic tankers have been exhausting their life span. At present, a significant number of northern refueling complexes have switched to the operation of foreign tankers based on Volvo and Mercedes-Benz tractors. The operation of these vehicles has already revealed a series of shortcomings which extremely complicate the normal procedures. There is an acute need to refine the components and assemblies in order to reduce the failures that affect the regularity and safety of aircraft flights. One of the main problems of fuel tankers operation at low temperatures is the malfunction of the electropneumatic bottom valve, due to its freezing. The paper proposed replacing this problematic node with a mechanical bottom valve, which is not susceptible to low temperatures. In order to avoid cracking of rubber products of the underwing refueling nozzle and to increase the flexibility of the dispensing hoses, it is proposed to carry out heating of the glass of the refueling nozzle and the filling module by means of exhaust gas bypass and pumping hot coolant through the system of nozzles. The most serious problems are the difficulties of operating a diesel-powered tractor at low temperatures. Problems arise already at startup. Diesel fuel at low subzero temperatures can thicken or even solidify, the lubricant also thickens. There have been cases when the startup was complicated by low compression in the cylinders. But even if the engine was able to start, after a while it may start to stall. This is due to oxygen starvation, which occurs because the icy air entrains water, which is deposited as frost on the air filters, thereby blocking the oxygen supply to the engine. After prolonged parking at low temperatures, during the first seconds of starting the piston engine, the parts come into contact with each other without lubrication. The reason is the viscosity of the oil which decreases at extremely low temperatures, therefore, in order for the lubricant to reach the end users through narrow oil pipelines, it takes some time to warm up (about 10 minutes). As a result of such cold starts and the risk of bullying on the parts of the piston group, their durability is reduced by more than 40%. When starting cold, the engine additionally warms up itself at higher idle speeds. To prevent undesirable consequences, as well as to create more favorable conditions for starting the diesel unit, reducing fuel consumption, it is proposed to use a pre-heater with an external power source from the 220 V electrical network. In order to facilitate the start of the diesel engine, it is necessary to provide the heating of the fuel line and fuel pump filters. To eliminate oxygen starvation of the engine, due to the formation of frost on the filter elements, and to increase the stability of the engine, it is necessary to provide the heating of the air filter.
These days, strict requirements to aeronautical equipment are imposed to enhance reliability, durability, and environmental compatibility. Aeronautical equipment operation reliability depends not only on its structural and technologic abilities, but also on the fact how aviation oils, fuels and technical fluid meet quality requirements during operation. During the aircraft engine operation, oils are subjected to the thermal impact. As a consequence, their properties and composition change which can affect the engine operation, on the whole. The most promising means of improving thermal resistance of aviation oils is developing new ones and improving available oil compositions. Therefore, it is feasible to analyze the kinetic properties of the oil thermal conversion which will make it possible to predict their resistance within the extensive temperature range. The paper investigates thermal decomposition kinetics of aviation oils MS-8P, TN-98 and TN-600 used on different types of aircraft in civil aviation of the Republic of Belarus by the method of a thermo-gravimetric analysis. The composition of oil samples has been researched into by IR spectroscopy, chromatography-mass spectroscopy methods. A comparative analysis of research results of new oils and oils drained from aircraft engines indicates that even under insignificant overheat during the operation, a change in the hydrocarbon composition occurs, and the hydrocarbon content of basic types varies to some extent. The oil thermolysis research reveals that potential overheat after engine shutdown complies with the temperatures at which the decomposition commences. Thermal conversion products of oil carbohydrates will contribute to the defect formation in friction subunits. As a result of test data processing of thermal conversion of aviation oils MS-8P, TN-98, TN-600, the principles of their decomposition as well as macrokinetic parameters, allowing us to precisely evaluate the effect of oils operation temperature conditions on their conversion rate, have been specified. It is essential while simulating the aircraft engine operation and predicting variations of oil quality properties during their operation.
MECHANICAL ENGINEERING
The article deals with issues related to the use of parametric information of the transient-state gas turbine engines (GTE) operation conditions for diagnosing their technical condition during the operation. A review of general approaches to computational algorithms for the recognition and classification of the condition applicable to aircraft GTE has been carried out. The significance of analytical models in modern algorithms for assessing the technical GTE condition is emphasized. The construction of a linearized mathematical model for the transient-state condition of the generalized-scheme aircraft GTE operation has been considered. It represents a system of equations analytically combining the relative parameter divergences measured during the engine operation with the relative divergences of unmeasured thermogasdynamic parameters and geometric gas-air flow duct parameters allowing for the technical condition of gas-air channel elements to be classified. A method for constructing mathematical and diagnostic engine models, using the transient response data, has been formulated. The capability of employing a method of insignificant divergences, used to build linear (linearized) mathematical and diagnostic GTE models for the steady-state conditions of its operation, has been demonstrated as well. It is shown that, despite the structural similarity of linear models of the steady and transient-state processes, diagnostics by means of the stated above processes is based on completely different principles – under the steady-state condition, the classification of a technical condition is determined by the variation in the value of the group of controlled responses, and under the transient-state condition, this operation is based on correlating the change in the transient-state behavior. To ensure the versatility of employing proposed methods regarding various GTE designs installed on modern civil aircraft, a generalized-design aircraft GTE model – a three-shaft bypass turbojet engine with mixing flows in a common jet nozzle, has been considered.
ISSN 2542-0119 (Online)