rss_2.0Transactions on Aerospace Research FeedSciendo RSS Feed for Transactions on Aerospace Research on Aerospace Research Feed and Estimating Local Corrosion Damages in Long-Service Aircraft Structures by the Eddy Current Method with Double-Differential Probes<abstract> <title style='display:none'>ABSTRACT</title> <p>Monitoring corrosion in aircraft structures through nondestructive testing is crucial for maintaining long-term aircraft serviceability. Corrosion monitoring is particularly challenging when corrosion damage is situated on internal surfaces of multilayer aircraft structures. The eddy current method is one of the most promising techniques for detecting and measuring such subsurface corrosion damage without direct contact or disassembly. However, due to their low sensitivity traditional eddy current probes with coaxial coils are not well suited for detecting corrosion damages of the local type, such as pitting or corrosion pits, in multilayer aircraft structures. This study tested the use of low-frequency eddy current probes of the double-differential type, characterized by 8 and 10 mm operational diameters, in detecting and measuring hidden corrosion damages of this local type. Such corrosion damages were simulated by means of flat-bottomed drilled holes of differing diameters and depths (or different diameters and residual thicknesses of the inspected sheet in the damaged area). The signals from the eddy current probes were evaluated in the complex plane using a universal eddy current flaw detector. The correlations between the amplitude and phase of the eddy current signal and depth of location of the local corrosion damages were analyzed. Results indicate that it is possible to estimate the residual thickness of the skin in locally corroded areas by measuring the eddy current signal phase, independently of the local corrosion damage diameter (size), providing useful information for residual service life determination.</p> </abstract>ARTICLEtrue Simulation-Based Methodology for Reducing The Risk of Fuel Fire In An Aircraft’s Fuel System Enclosure<abstract> <title style='display:none'>ABSTRACT</title> <p>This study applies advanced computational fluid dynamics (CFD) simulations to enhance the safety of an aircraft’s fuel system by striving to minimize the risk of on-board fire hazards. Employing a detailed flow simulation model, this research assesses the efficacy of newly designed measures within a fuel system, designed for a modified radial engine on a test-bed AN 2 airplane. The model simulates internal airflow, droplet particle flow, the formation of Eulerian Wall Film, and the vaporization process from the fuel film within the enclosure of the aircraft’s equipment bay. By exploring both the original and modified geometries of this fuel system enclosure, the simulations provide insights into the flowpaths of leaking fuel, the spatial and temporal distribution of fuel vapor concentrations, and the overall effectiveness of design modifications aimed at rapid removal of hazardous substances. Structural improvements, including the addition of strategic ventilation inlets and outlets, are proposed based on the simulation results to ensure rapid dispersion of vapors and minimal residual fuel, effectively reducing the potential for vapor ignition. This study thus underscores the potential of precise CFD modelling in identifying risks and developing robust fire hazard mitigation strategies in aviation fuel systems.</p> </abstract>ARTICLEtrue of Eddy Current Array Performance in Detecting Aircraft Component Defects<abstract> <title style='display:none'>ABSTRACT</title> <p>Eddy current array (ECA) technology is increasingly being used in the aerospace industry for non-destructive testing of aircraft components. This study evaluates the performance of ECA in detecting defects in aircraft components, focusing on its effectiveness, reliability, and sensitivity. The study evaluates the effectiveness of ECA technology in eddy current defectoscopy by introducing a dimensionless efficiency coefficient, then seeks to validate this coefficient through experimental testing of aircraft component materials with artificially induced defects of various sizes, types, and orientations to simulate real-world scenarios. ECA’s sensitivity in detecting small and subsurface defects is analyzed, along with precise defect sizing and positional information. Reliability and repeatability are investigated through repeated measurements. Furthermore, the article analyses the impact of various factors on the performance of ECA, including surface conditions, probe configurations, and inspection parameters. Comparative analysis is performed to assess the advantages and limitations of ECA in comparison to other conventional inspection methods. The findings of this study will contribute to a better understanding of the capabilities and limitations of ECA in detecting aircraft component defects. The results will aid in optimizing inspection strategies, enhancing the reliability of defect detection, and improving the overall maintenance practices in the aerospace industry.</p> </abstract>ARTICLEtrue Command Recognition in Air Traffic Control Through Advanced Classification Techniques<abstract> <title style='display:none'>ABSTRACT</title> <p>This paper addresses the persistent challenges in speech processing within the Air Traffic Control (ATC) domain, a field where despite extensive research, issues such as handling noisy environments, accented speech, and the need for strict adherence to standard phraseology continue to undermine conventional language models. Our study employs a hybrid approach that integrates syntactic analysis with advanced machine learning classification algorithms – Logistic Regression, Lagrangian Support Vector Machine, and Naïve Bayes. By mixing and matching algorithms tailored for specific aspects of speech processing, our approach moves away from traditional reliance on a singular integrated system, illustrating through rigorous testing with the ATCOSIM dataset that such a multifaceted strategy markedly improves command recognition accuracy and adapts more effectively to the unique linguistic features of ATC speech. Results highlight the superior performance of Logistic Regression across various command recognition categories, pointing towards a promising direction for future advancements in ATC speech recognition technologies aimed at reducing human workload and increasing automation precision. This paper explores the complexities of the required analysis techniques and underscores the necessity of employing diverse algorithms in the processing pipeline to enhance overall system accuracy.</p> </abstract>ARTICLEtrue Simulation of Workflow for Evaluating Flame Tube Thermocyclic Durability<abstract> <title style='display:none'>ABSTRACT</title> <p>This paper explores strategies for extending the operational lifespan of flame tubes in turbofan engines – a critical component for maintaining engine efficiency and reliability, in line with global trends aimed at maximizing the use of laid reserves of aircraft engine performance. Utilizing a combination of advanced computational simulations and empirical research, the study meticulously analyzes the internal processes within the flame tube of the AL-31F turbofan engine. A detailed geometric model and finite element grid were created and adapted to simulate various operating conditions and assess their impact on the flame tube’s performance. Special attention is given to understanding the thermal and mechanical stresses that influence its durability and serviceability. The results, compared against experimental data, validate the simulations and are crucial for identifying critical sections prone to damage, thereby facilitating enhanced decision-making regarding maintenance schedules and overhaul practices. This approach not only aims to minimize downtime and reduce maintenance costs but also extends the service intervals for critical engine components, thereby improving thermocyclic durability based on the damage mechanisms identified.</p> </abstract>ARTICLEtrue of Approaches to Assessing Flight Delays Due to Technical Issues at Airline Network Airports Within the Operational Management Framework<abstract> <title style='display:none'>ABSTRACT</title> <p>This paper analyzes approaches to developing models for the technical exploitation (TE) of aircraft within operational management framework. The operational management contour of the TE of the airline’s AC fleet is considered as a TE process consisting of a sequence of flight routes, which, in turn, comprise a sequence of flights between airports in the airline network during the calendar interval when the aircraft are in this contour. We present a model that evaluates the capacity for aircraft recovery at the network airports of a hypothetical airline (dubbed “RAF”) if the need so arises, utilizing the probabilistic and temporal characteristics of the airports used for aircraft recovery.</p> </abstract>ARTICLEtrue Strut Fairing System Expluatation and Critical Path Method Use<abstract> <title style='display:none'>ABSTRACT</title> <p>The flap strut fairing system is made of movable construction inside, but the outer skin is made of composite material. Each day, we can face an expensive repair for movable construction and outer skin as most of the aviation companies are dealing with mechanical issues that are not solved during a long period of time or somebody misses it due to human errors. In this abstract, we will look for options for easier and faster solutions to avoid the expensive operation process.</p> </abstract>ARTICLEtrue of Stability Criteria of Automatic Control Systems By Multiparametric Aviation Objects<abstract> <title style='display:none'>ABSTRACT</title> <p>This paper considers the comparative analysis of the physical and mathematical methods of the optimal operation of aviation objects’ automatic control systems, which is an urgent scientific and technical task. The paper also represents the corresponding stability criteria, depending on the operating conditions, and the influence of external factors that allows ensuring the automatic control systems’ reliable operation not only in normal circumstances, but also in the presence of probable disagreements. The scientific novelty of the research lies in developing new stability criteria by means of synthesising the influence of different factors and also the ability to ensure optimal functioning of the automatic control systems. Corresponding mathematical and computer models have been developed. The use of these models allows to determine the optimal stability criteria for control systems with parameters of a different physical nature and ensure reliable operation of electromechanical systems for general and special applications based on the current analysis. The research results are illustrated by corresponding mathematical models, engineering calculations and modelling of the optimal control limits depending on the influence of various factors. The simulation results coincide with the theoretical calculations, which indicates the consistency between the microprocessor-based and software of automatic control systems.</p> </abstract>ARTICLEtrue Analysis of Wind Parameters at the Planned Construction Sites of Wind Generators<abstract> <title style='display:none'>ABSTRACT</title> <p>To choose optimal place for wind turbine, you need to know two basic parameters: <list list-type="order"> <list-item><p><italic>V</italic><sub>average</sub> – the average wind throughout the year (or during the season when more electricity is needed). The total amount of kilowatt hours of electricity you will get, depends on this parameter.</p></list-item> <list-item><p><italic>V</italic><sub>max</sub> – the maximum possible dangerous gust of wind during a storm. The required strength depends on this parameter and hence the cost of construction.</p></list-item> </list></p> <p>In order to evaluate the place itself, it is possible to combine these two parameters to only one physical parameter: <italic>V<sub>Bojat</sub></italic> – the average wind speed which is devaluated by hurricanes.</p> <p>In this article, it is called: “Bojatspeed”: <inline-formula><alternatives><inline-graphic xmlns:xlink="" xlink:href="graphic/j_tar-2024-0006_ieq_001.png"/><mml:math xmlns:mml="" display="inline"><mml:mrow><mml:msub><mml:mi>V</mml:mi><mml:mrow><mml:mtext>Bojat</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:msubsup><mml:mi>V</mml:mi><mml:mrow><mml:mtext>average</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msubsup></mml:mrow><mml:mrow><mml:msubsup><mml:mi>V</mml:mi><mml:mrow><mml:mi>max</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msubsup></mml:mrow></mml:mfrac></mml:mrow></mml:math><tex-math>\[{{V}_{\text{Bojat}}}=\frac{V_{\text{average}}^{3}}{V_{\max }^{2}}\]</tex-math></alternatives></inline-formula>.</p> <p>Measurements for <italic>V</italic><sub>average</sub> must be done for at least a year, but for <italic>V</italic><sub>max</sub> for at least ten years. They are obligatory before any decision about construction of wind turbine. And not generally in the country, but exactly in the particular place. A system of two devices for such measurements is described in this article: anemometer and brazmometer. Both are made in Latvia. They are purely mechanical and include no electronics – that is why they do not require battery or any service during many years.</p> </abstract>ARTICLEtrue Approach to Landing<abstract> <title style='display:none'>ABSTRACT</title> <p>The article describes the problem of controlling an aircraft control when performing a landing on a curvilinear trajectory. The adoption of a curvilinear approach trajectory allows reducing the impact of air traffic on the areas adjacent to the airport. Performing the correct approach on the curvilinear path requires support. For the correct execution of the landing manoeuvre on the curvilinear track, it is necessary to establish reference points so that the repeatability of the manoeuvre is ensured, especially in the case of landing more than one aircraft at the same time. In the following parts, the landing control system is presented. Particularly carefully presented is the issue of performing tests of the designed control system, which in the case of the aircraft control system during the approach to landing must be extremely thoroughly verified. The test plan included both verification the correctness of the adopted control laws and their robustness to interference occurring as a result of atmospheric air streams.</p> </abstract>ARTICLEtrue and Design of the Main Equipment for Mobile Space Simulation System<abstract> <title style='display:none'>ABSTRACT</title> <p>This article presents the results of the analysis of approaches to designing a mobile vacuum system ‘METAMORPHOSIS’ for simulation of space environment, which could help provide services of testing space objects at the request of the customers at a place and time acceptable to them, which allows saving time and assets in the development of space objects, their elements, including satellites. As a result of the conducted analysis, methodological approaches to the determination of the structure of the vacuum system were undertaken. To avoid unanticipated issues and to validate computer-driven modelling, testing in a space simulation chamber is an important part of the quality-assurance process. Spacecraft and their components must withstand extreme temperatures and pressure to travel outside the Earth’s atmosphere. Space simulation testing involves the use of a thermal vacuum chamber to replicate the conditions experienced in space.</p> </abstract>ARTICLEtrue Blowing-Suction Schemes for Manipulating Turbulent Boundary Layers<abstract> <title style='display:none'>ABSTRACT</title> <p>The methodology of efficiency analysis of turbulent flow modification by making permeable sections in the streamlined wing surface with the aim to reduce aerodynamic drag is the principal subject of the presented research. The numerical analysis of the effect of laterally and longitudinally located permeable sections on boundary-layer properties showed the following flow features: (1) the most effective place for permeable surface is an upwind side of the wing; (2) multi-sectional blowing can simply be organised as non-uniform (especially in the case of laterally arranged permeable sections) that brings additional flexibility to change the blowing intensity depending on flight mode and, first of all, on angle of attack; and (3) arrays of longitudinal permeable sections allow to intensify turbulent vortical structures exchange in the lateral direction and improve flow stability to stall. Moreover, due to creating the regular anisotropy of the boundary layer in the lateral direction, this modified blowing technique can potentially have some synergistic properties, which can give the additional benefit. All these effects are too delicate and their experimental study cannot be performed with the use of directed measurements of aerodynamic forces. The comparison of the obtained flow properties with the corresponding experimental data demonstrates an appropriate level of agreement.</p> </abstract>ARTICLEtrue of Failure States of Functional Systems of Aircraft Such as Boeing 737 in the Airline<abstract> <title style='display:none'>Abstract</title> <p>The article presents the results of analysis of failures of the main functional systems units of aircraft Boeing 737 during the last 10 years of its operation in the national airline of Latvia ‘Air Baltic Corporation’. Total flight time was T<sub>∑</sub> = 322,529 h and 184,538 cycles [<xref ref-type="bibr" rid="j_tar-2023-0024_ref_001">1</xref>]. These data were obtained from daily reports of defects and unplanned consumption of spare parts for these systems. Failures of instrumental equipment of avionic systems were investigated in detail. Based on calculations of their failure probability and component replacement frequency, a comprehensive system including measures and their technical and instrumental support has been developed to improve maintenance productivity. Such a system requires relatively inexpensive components, is simple and can be used in the operation of this type of aircraft.</p> </abstract>ARTICLEtrue Modelling of Static Aeroelastic Deformations of Slender Wing in Aerodynamic Design<abstract> <title style='display:none'>Abstract</title> <p>The article presents the validation of two methods for analyzing the aerodynamic properties of the aircraft wing concerning aeroelastic effects. The first method is based on low-cost computational models (Euler–Bernoulli Beam Model and Vortex Lattice Method [VLM]). Its primary objective is to estimate the wing’s deformation early in the design stages and during the automatic optimization process. The second one is a method that uses solutions of unsteady Navier–Stokes equations (URANS). This method suits early design, particularly for unconventional designs or flight conditions exceeding lowfidelity method limits. The coupling of the flow and structural models was done by Radial Basis Functions implemented as a user-defined module in the ANSYS Fluent solver. The structural model has variants for linear and nonlinear wing deformations. Features enhancing applicability for real-life applications, such as the definition of deformable and nondeformable mesh zones with smooth transition between them, have been included in this method. A rectangular wing of a high-altitude long-endurance (HALE) aeroplane, built based on the NACA 0012 profile, was used to validate both methods. The resulting deflections and twists of the wing have been compared with reference data for the linear and nonlinear variants of the model.</p> </abstract>ARTICLEtrue Eddy Current System for Aircraft Structure Inspection<abstract> <title style='display:none'>Abstract</title> <p>Aircraft part diagnostics are crucial during both production and maintenance, with eddy current nondestructive testing (ECNDT) being the method of choice due to its cost-effectiveness, informativeness, productivity, and reliability. ECNDT excels regardless of surface condition or coatings. It’s employed for diagnosing various aircraft components, necessitating diverse transducer types, excitation modes, and advanced signal processing. To improve ECNDT, this article explores integrating harmonic and impulse excitation modes in a single tool to enhance informativeness. Building upon a wireless eddy current system, the authors propose a comprehensive method for processing and displaying information suitable for object condition monitoring systems. The system includes automated transducer mode control and experimental data processing algorithms. The constant expansion of tested objects and new materials underscores the need to enhance the theoretical foundations of eddy current non-destructive testing, refine signal processing techniques, and identify informative signs. This demands the development of new automated ECNDT tools, and this article offers a promising avenue for improvement. The results include model and experimental tests of system components, showcasing the potential of this approach to enhance ECNDT effectiveness, automation, and informativeness in the realm of aircraft part diagnostics.</p> </abstract>ARTICLEtrue Strapdown Inertial Navigation System Performance by Self-Compensation of Inertial Sensor Errors<abstract> <title style='display:none'>Abstract</title> <p>Microelectromechanical systems (MEMS)-based strapdown navigation systems offer advantages such as small size, low cost and minimal power consumption. However, MEMS sensors are prone to significant low-frequency noise and poor bias repeatability, which can lead to navigational errors over time. These errors make them unsuitable for autonomous navigation applications, even with frequent recalibration. One way in which to solve this problem is by using the rotation modulation (RM) method. This approach is widely recognised but has only been successful with precise laser and fiber optic gyroscopes equipped with precise rotating platforms. This article focuses on the potential of adapting the RM method for the case of inexpensive MEMS sensors that can significantly improve navigation performance, while maintaining the benefits of microelectromechanical technologies. Potential issues of implementation were discussed, and corresponding requirements were formulated. The proposed optimal computation scheme was verified during static tests of the developed inertial measurement unit (IMU). Further steps in studying the adaptation of the RM method for MEMS sensors have also been outlined.</p> </abstract>ARTICLEtrue Operating Window in Selective Laser Melting Processes<abstract> <title style='display:none'>Abstract</title> <p>Selective laser melting (SLM) is one of the most effective methods of additive manufacturing (AM). It is used to manufacture products with very complex geometries using a wide range of materials. Practical process conditions are limited by the occurrence of undesirable melting instabilities that degrade the surface quality and lead to product defects. These disadvantages are related to the thermal limitations of the SLM process. The lower thermal limit is due to the need to completely melt the powder layer and partially remelt the underlying layer again to ensure proper bonding between the layers. Exceeding the upper thermal limit in the molten metal pool may cause extensive evaporation, boiling and ejection of molten metal droplets outside the melting area. The article presents an approach and methodology that enable the determination of thermal limits and the operating window of SLM/selective laser sintering (SLS) processes in a relatively simple way. The studies have been performed using various settings of SLM process parameters. The usefulness of the preliminary determination of thermal limitations and approximate prediction of operating window of SLM has been confirmed experimentally and by more accurate computer simulation.</p> </abstract>ARTICLEtrue Tonal Noise Prediction Using Urans<abstract> <title style='display:none'>Abstract</title> <p>To examine the feasibility of the laminar boundary layer (LBL), vortex shedding (VS) tonal noise modelling using unsteady Reynolds-averaged Navier–Stokes (URANS) was investigated for the non-symmetric S834 airfoil. A transition SST turbulence model was used to model the laminar-turbulent transition and its vital influence on the laminar bubble and hydrodynamic instabilities generation. The influence of turbulence on the unsteady vortex patterns was investigated. Hence, the hybrid aeroacoustic analysis with Lighthill analogy was conducted to obtain the acoustic pressure field. The approach allowed us to model hydrodynamic instabilities and the resulting VS tonal noise. The frequency of VS matched the experimental data, giving the same 1/3 octave tonal peak only for a limited freestream turbulence regime. The simplification of the present method did not allow us to model the aeroacoustic feedback loop, and resulted in lack of instabilities for higher freestream turbulence.</p> </abstract>ARTICLEtrue Venturi as a Mass Flow Controller in a Deep Throttling Liquid Rocket Engine<abstract> <title style='display:none'>Abstract</title> <p>The most common solutions for rocket engines are the single operation point (thrust level) units. Oxidiser and fuel mass flow rates and the oxidiser-to-fuel mass flow rate ratio (OFR) are some of the determinants of the thrust level. Based on these, planetary ascent and descent; space rendezvous; orbital manoeuvring, including orientation and stabilisation in space; hovering, hazard avoidance during planetary landing; and ballistic missile trajectory control propulsion systems could use throttleable liquid engines. Several engine throttling methods, such as supply pressure variation and variable injector area, can be applied. Among others, a cavitating venturi propellant regulatory valve is one of the most promising throttling method. This type of valve can provide steady mass flow, despite the downstream pressure disturbance (i.e. from the combustion chamber), which sustains a stable engine thrust as the mass flow is kept. The article presents the valve sizing method, design and prototype test results of the cavitating venturi valve that has potential for utilisation in a deep throttling rocket engine. Mass flow stability and repeatability are presented for valve operating points in the 10%–110% nominal mass flow range. Valve design optimisation, based on CFD, to sustain cavitation for a higher downstream-to-upstream pressure ratio is shown.</p> </abstract>ARTICLEtrue Principles and Mechanical Considerations of Satellites: A Short Review<abstract> <title style='display:none'>Abstract</title> <p>Satellites are used for navigation, communication, oceanography, astronomy, etc.. Satellites come in a diversity of sizes and forms. Depending on the satellite’s mission, different subsystems are used. These subsystems are installed inside a housing to protect them from the space environment. This housing, which is also known as the satellite primary structure or mechanical structure, is made of durable materials that can endure severe conditions during launch and in the orbit. The optimisation of satellite mass is crucial right now since satellites are losing mass every day to reduce the cost of manufacturing and launching. This review first introduces an overview of the satellite classifications and subsystems. Then, the different types of mechanical load analysis the satellite subjects itself to are demonstrated. The advanced approaches for promoting the performance of the mechanical structures of satellites are explored, with a spotlight on the effect of the optimisation parameters of isogrid and honeycomb sandwich structures on the mechanical performance of the satellite primary structure. The assembly, integration and testing (AIT) of the small satellite are briefly presented. Finally, the important potential designs to improve the mechanical performance of the satellite primary structure and the challenges of further research are summarised.</p> </abstract>ARTICLEtrue