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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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Transactions on Aerospace Research
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0509-6669 - ISSN (Online) 2545-2835
Published by Sciendo Homepage  [370 journals]
  • Eddy Current Techniques for Detecting Hidden Subsurface Defects in
           Multilayer Aircraft Structures

    • Abstract: In-service non-destructive inspection (NDI) is a very important part of the aircraft maintenance program that minimizes aircraft breakdowns due to the fracture of critical components. The eddy current (EC) NDI method is one of the most applicable methods for this purpose, due to its high sensitivity to fatigue cracks and corrosion damage in the main structural materials. In this paper, selective double differential type EC probes characterized by the enhanced possibility of detecting subsurface cracks initiated by fatigue or stress corrosion phenomena are presented. For different applications, a family of double differential type EC probes was developed with different sizes (from 5 to 33 mm) and different spatial resolutions. These types of probes are characterized by different operational frequencies in a wide frequency range (from 0.2 kHz to 1.0 MHz), high penetration depth and unique sensitivity to subsurface defects of different types (like elongated fatigue cracks or local corrosive pitting), and a high level of specific noise suppression concerned with the scanning inspection procedures. The EC probes proposed were investigated as effective tools for characteristic aircraft applications concerned with subsurface defect detection in multilayer structures, such as the detection of cracks in the second layer of a riveted two-layer structure or cracks initiated on the side surface of a multilayer structure with the suppression of the reinforcing hoop influence; the detection of subsurface defects in arc welding with a rough surface; the detection of cracks through repair patches fabricated from aluminum alloy or carbon fiber reinforced plastic, etc. These techniques create remarkable possibilities for the well-timed detection of dangerous damage without disassembling the aircraft structure or removing protective coating.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • Comparing Methods of Calculating Aircraft Engine Emissions of Harmful
           Exhaust Components During the Takeoff and Landing Cycle in the Airspace of
           an Airport

    • Abstract: An airport authority needs accurate information about the actual amount of harmful emissions being generated within its airspace, to be able to take measures leading to their reduction. This article presents two methods for estimating the amount of these emissions from aircraft engines during the take off and landing cycle (LTO) in the airspace of a medium-sized airport: one based on the total amount of the aircraft annually operated in it, and a second, more precise, one for a specific airline annually operating at this airport. The conclusions stemming from the comparison of these methods can support the introduction of operational and technical procedures reducing harmful emissions in the airport airspace during LTO cycle.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • Feasibility Study for a Fuel Cell-Powered Unmanned Aerial Vehicle with a
           75 Kg Payload

    • Abstract: Among the possible electric powerplants currently driving low-payload UAVs (up to around 10 kg of payload), batteries offer certain clear benefits, but for medium-payload operation such as aerotaxis and heavy-cargo transportation UAVs, battery capacity requirements restrict their usage due to high weight and volume. In light of this situation, fuel cell (FC) systems (FCS) offer clear benefits over batteries for the medium-payload UAV segment (> 50 kg). Nevertheless, studies regarding the application of FCS powerplants to this UAV segment are limited and the in-flight performance has not been clearly analysed. In order to address this knowledge gap, a feasibility analysis of these particular applications powered by FCS is performed in this study. A validated FC stack model (40 kW of maximum power) was integrated into a balance of plant to conform an FCS. As a novelty, the management of the FCS was optimized to maximize the FCS efficiency at different altitudes up to 12500 ft, so that the operation always implies the lowest H2 consumption regardless of the altitude. In parallel, an UAV numerical model was developed based on the ATLANTE vehicle and characterized by calculating the aerodynamic coefficients through CFD simulations. Then, both models were integrated into a 0D-1D modelling platform together with an energy management strategy optimizer algorithm and a suitable propeller model. With the preliminary results obtained from the FCS and UAV models, it was possible to ascertain the range and endurance of the vehicle. As a result, it was concluded that the combination of both technologies could offer a range over 600 km and an endurance over 5 h. Finally, with the integrated UAV-FCS model, a flight profile describing a medium altitude, medium endurance mission was designed and used to analyse the viability of FC-powered UAV. The results showed how UAVs powered by FCS are viable for the considered aircraft segment, providing competitive values of specific range and endurance.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • The Contribution of A. K. Oppenheim to Explaining the Nature of the
           Initiation of Gaseous Detonation in Tubes

    • Abstract: This paper analyzes A.K. Oppenheim’s original works on the transition of deflagration to detonation and reviews them from the perspective of new numerical and experimental results recently obtained on such phenomena. Particular attention is focused on processes happening in the boundary layer of the tube walls ahead of the accelerating flame. The results of the theoretical analyses of temperature variations inside developing boundary layer are presented and compared to the temperature variation in a free stream away from the boundary layer. Analyses of temperature increase in such layers clearly indicate that the self-ignition of the mixture happens in the boundary layer ahead of the propagating flame front. New experimental results obtained recently by a research group from the A. V. Luikov Heat and Mass Transfer Institute in Minsk, Belarus, combined with previously conducted theoretical analyses and numerical simulations, show clearly and unambiguously that the origin of the “explosion in the explosion”, postulated by A. K. Oppenheim in 1966, is always responsible for the Deflagration-Detonation Transition (DDT) in gases and is located in the boundary layer ahead of the accelerating flame front.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • Development of a Flight Simulator for Conceptual Aircraft Design and
           Sizing

    • Abstract: This article describes the development of a flight simulator module within the ADEMAO aircraft design framework to investigate the effects of novel airframe and propulsion technologies on new generations of aircraft. Methods used to develop and integrate the fight simulator into the overall design framework are described. The simulator is validated based on existing data from the Convair CV-880M and is then used to analyze an example case of a conceptual medium-range aircraft with advanced airframe technologies designed in the Sustainable and Energy-Efficient Aviation research cluster at the Institute of Aircraft Design and Lightweight Structures at the Technische Universität Braunschweig. Results show the deficiencies of the medium-range aircraft in short-period pitch and Dutch roll performance, and recommendations for modifications to the conceptual medium-range aircraft are drafted.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • Diagnostic Model of Aircraft Turbine Engine Governor Pump

    • Abstract: This paper presents a mathematical model for a hydromechanical fuel governor pump, to be used in parametric diagnostics. The design and operation of the governor are described. The main requirements of the model are formulated, its structure is determined, corresponding to the specifics of the diagnostic task, and assumptions to make the model simpler are presented (single-dimensional flow and absence of heat exchange). The presented model consists of idealized elements with lumped parameters (such as pressure and mass consumption of the working fluid), accounting for the compressibility of the substance and the design arrangement of the governor (presence of mechanical rests, metering orifices of complex shapes, relay switchers, etc.). Equations of elements with lumped parameters, linked by hydraulic channels in one node, are presented. The model – a system of first-order differential-algebraic equations – is solved and the parameters of the governor pump are determined for different steady-state and transient operation modes. We compare our results to the requirements for the corresponding parameters outlined in the Engineering Specifications. The model is matched to the specifications by correcting setting parameters (tightening of elastic springs, areas of throttles, etc.), and a method of initial model linearization is developed. Based on the results, we conclude that our model can be used as a diagnostic algorithm for a governor pump, at the testing and development stages, during manufacturing, repair and maintenance.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
       
  • Threats to Aviation Safety Caused by Defects in Aircraft Airframe Systems

    • Abstract: Alongside the increase in air traffic and number of aircraft, the number of reported aviation events has also been increasing. We processed the data included in the European Coordination Centre for Aviation Incident reporting Systems (ECCAIRS), analyzing small and large aircraft reliability and the safety of their operations, covering events according to ICAO aviation occurrence categories. Airframe systems are the largest contributor to the total number of reported events which occurred in Polish registered aircraft in the years 2008–2020. A detailed study of airframe systems reliability was carried out in order to assess the real reason for the failures. Airframe systems faults were assigned to specific ATA chapters and then to each of their sections. The results of this analysis may support the decisions of supervisory authorities in the areas where security threats are most important. They can also help aircraft operators with identification of the airframe units which require special attention. Identification of significant parts due to the frequency of malfunctions of particular system components may support designers. In short, these results are valuable in terms of further developments in statistical tools facilitating New Product Introduction (NPI).
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • Theoretical and Methodological Approaches to the Information Base for an
           Airline’s Flight Safety System

    • Abstract: This article presents a model and an algorithm for identifying, collecting, processing, analyzing and using data on risks at an airline (deviations from the standards in the activities of various airline units and personnel) to minimize them and thereby to achieve an acceptable level of flight safety. A methodology is also presented for formulating the composition of flight safety indicators, based on an expert approach, for the units and personnel of the airline, making decisions in this field in various areas of its activities. The model is based on the quality and flight safety systems that form part of an integrated management system at one of Latvia’s airlines. The system makes it possible to analyze safety aspects on the basis of actual information drawn from various sources into the airline’s information base, where it is collected, classified, stored and analyzed.
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • A CFD Study of the Aerodynamic Characteristics of Twardowsky and FOK
           Rockets

    • Abstract: Stability and performance are crucial characteristics for aerospace vehicles. The ability to investigate the aerodynamics and performance of rockets gives an insight into their stability before flight and the potential for design and performance enhancements. For the past 13 years, the rocketry Division within the students’ space Association of Warsaw University of technology has been developing sounding rockets of different designs and mission profiles. Two rockets have been chosen for the CFD (Computational Fluid Dynamics) campaigns, FOK and Twardowsky. This paper describes the mathematical model of aerodynamic loads used by the Division for sounding rocket simulation, followed by CFD campaigns for the two rockets. The results of the CFD analysis are then used to calculate the rockets’ aerodynamic derivatives according to a previously defined mathematical model.
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • Measuring Exposure to High-Frequency Electromagnetic Fields Experienced by
           a Helicopter Crew During Flight

    • Abstract: High-frequency electromagnetic fields (EMF) can have a negative effect on both the human body and electronic devices. Monitoring and measurement of the electromagnetic field generated by devices is important from the point of view of environmental protection, the human body and electromagnetic compatibility. In this study, we tested the value of the electromagnetic field strength determined by the NHT3DL by Microrad with measurement probes during flights in the Robinson R44 helicopter. The reference point for the results obtained were the normative limits of the electromagnetic field permitted to affect the crew and passengers during flight. The maximum RMS values recorded during the measurements were E = 4.399 V/m in the 100 kHz–6.5 GHz frequency band and for the magnetic component H = 2.829 A/m in the 300 kHz–30 MHz frequency band. These results were passed to the Statistica 13.3 software for a detailed stochastic analysis of the values tested.
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • Method of Designing a Distortion Gauze for Testing a Boundary Layer
           Ingesting Fan

    • Abstract: As global trends aim to reduce emissions of pollutants, boundary layer ingesting (BLI) propulsions are attracting more and more attention. As such, N+2 generation aircraft with propulsion placed in the aft of the aircraft are gaining in popularity. The boundary layer is formed on the fuselage before entering the engine located in the aft of the aircraft. Due to significant difficulties in performing experimental tests of BLI propulsors with full-size aircraft, distortion gauzes are one of the methods to provide the desired air velocity profile at the inlet. This paper describes a novel method of designing such gauzes, a topic which is not well covered in the existing literature. In the first stage of the presented method, single orifices of different sizes were calculated using CFD tools. The relationship between their size and the gauze resistance coefficient was identified, making it possible to model the distortion gauze using porous media. An iterative approach was used to design a gauze that meets the requirements. This is, to our knowledge, the first distortion gauze design description where a porous media model has been used. Experimental tests demonstrated that the produced distortion gauze yields a velocity profile comparable to the desired one. This indicates the great potential of using the presented approach in further research on boundary layer ingesting propulsions. It offers an opportunity to reduce substantially both the costs of experimental research and the time required to design a distortion-tolerant fan.
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • Solving a Certain Two-Alternative Problem in the Optimal Organization of
           Aviation Transportation in Conditions of Uncertainty

    • Abstract: This paper proposes a solution to a certain two-alternative problem of aviation transportation optimal organization in conditions of uncertainty of the subjective preference functions. Conditional optimization of the objective functional containing the entropy of the individuals’ operational effectiveness functions preferences is carried out in the framework of the simplest variational problem. The advantages of the described optimization approach are demonstrated in the generalized terms of the operational effectiveness functions for aviation transportation organization.
      PubDate: Tue, 22 Mar 2022 00:00:00 GMT
       
  • A Comparative Structural Analysis of Four Radiosonde Models

    • Abstract: In this study, we first performed a comprehensive structural analysis of four models of radiosondes (devices intended for use as the meteorological probe of a sounding balloon) manufactured by three different companies – Graw, Vaisala and Meteomodem. The radiosondes were disassembled for visual inspection and manual measurement, three-dimensional computed tomography images were taken of their inner structure, and the outer shapes of the radiosondes were scanned with a structured-light three-dimensional scanner. The structural properties of the radiosondes thus identified were then compared to one other, based on which the Meteomodem M10 was ranked as the least harmful in a potential collision. Next, the Meteomodem M10 radiosonde was used in collision tests with a heavy target and with a pumpkin model, in order to evaluate the possible damage caused by and to the radiosonde in different types of collisions.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • Determining the Aerodynamic Characteristics of a Propeller-Driven Anti-UAV
           Fighter While Designing Air Propellers

    • Abstract: Given the rising importance of unmanned aerial vehicles (UAVs), this article addresses the urgent scientific problem of determining the aerodynamic characteristics of a UAV while laying out the propellers for the wings. We discuss the methodology for experimental wind-tunnel studies of aircraft configurations with propellers. It is shown that a characteristic feature of the configuration small-elongation wing with propellers is the absence of elements that are not affected by propellers. This feature makes it difficult to implement and automate a wind tunnel experiment, since there are problems with providing similar criteria for a working propeller; it is difficult to achieve perfect balancing for solid drive propellers, which causes vibration, the level of which depends on uncontrolled factors; the inability to neglect the presence of the body elements influence to the blades of propellers; the difficulty of direct measuring propeller thrust and torque. The presented methodology involves the integrated usage of experimental and numerical methods to eliminate the difficulties in conducting physical experiments in a wind tunnel. This approach makes it possible to combine the high credibility of experimental data in the study of the physical essence of phenomena with high efficiency and accuracy in determining aerodynamic characteristics by numerical methods. Using this approach, we established dependences of the aerodynamic characteristics of the small-elongation wing configuration with counter-rotating propellers on the geometric and kinematic parameters of the configuration for other extensions and constrictions of the wings. These data can serve as the basis for the development of recommendations for the selection of sensible geometric parameters of the aerodynamic configuration of a small-elongation wing with counter-rotating propellers.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • Numerical Simulation of the Deflagration to Detonation Transition in a
           Tube with Repeated Obstacles: Experimental Scale Simulation Using the
           Artificial Thickened Flame Method

    • Abstract: The Artificial Thickened Flame (ATF) method, which involves artificially increasing the flame thickness so as to simulate with a coarse grid resolution, is applied to reduce the computational cost of predicting the Deflagration to Detonation Transition (DDT) in a tube with repeated obstacles. While simulation results depended on the parameter N (the number of grid points in laminar flame thickness), it was found that N values of more than 10 may be excessive. The results show that the chosen simulation method predicts the flame speed as compared to a reference experiment and captures the detail of the strong ignitions near the corner between the obstacle and the sidewall. The present simulation also captures the wrinkle flame front structure during the acceleration of flame.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • Prospects for the Implementation of New Materials and Technologies in the
           Aerospace Industry

    • Abstract: This article considers the main materials used to make aircraft, both fuselage and engines. First, the problems that force developers to introduce new materials in aircraft production are identified. We then present features of the introduction of heat-resistant titanium alloys, ways of improving the mechanical properties of parts made of titanium alloys, and methods of manufacturing complex details. Other promising materials for the aviation industry, such as high-entropy alloys, quasicrystals, carbon-carbon materials, and nickel foam, are also considered.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • The KhAI-90 Light Civil Turboprop Airplane Pilot Project

    • Abstract: The pilot project of new light civil turboprop aircraft, called the KhAI-90, featuring a cruising speed of 350km/h, payload of 600 kg at 500 km range, and equipped with two turboprop Rolls-Royce 250-B17F engines each with power of 420 hp (alternatively, two AI-450C engines each with power of 450 hp may be installed) is presented herein. Based on the developed technical task, the concept for creating the KhAI-90 new competitive light civil aircraft, and the analysis of prototypes’ aircraft parameters and characteristics, the main tactical and technical requirements are assigned. The take-off weight of the new aircraft is determined in three approximations at the preliminary design stage of light civil turboprop aircraft, using the iterative software “CLA-TOW”, studying the influence of the wing geometric parameters and lift devices on aerodynamic performance, the power-to-weight ratio and the airplane weight parameters. The following parameters are calculated for the design: minimum take-off weight WTO min = 3,600 kg, optimal wing loading p0 opt = 130 daN/m2, optimal aspect ratio 9.6, taper ratio 2.25, sweep angle at leading edge 3 degrees, airfoil relative thickness 10.6%. A general view and three-dimensional parametric models of the master-geometry and passenger cabin space distribution are constructed for the KhAI-90 by means of the SIEMENS NX computer integrated system. More broadly, this pilot project has also demonstrated the viability of the method we developed and previously reported for determining light civil turboprop airplane parameters.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • Using Heinrich’s (Bird’s) Pyramid of Adverse Events to Assess the
           Level of Safety in an Airline

    • Abstract: One of the key concepts in matters of flight safety is that of special (abnormal) situations, with airworthiness regulation and certification of aviation equipment being based on this concept. At the same time, one is forced to admit that today there is no explicit interpretation of the standardized traits of special situations, nor are they not fully elucidated in the scientific literature. In this article we propose a pyramid-based approach to interpreting special (abnormal) in-flight situations, which allows for risk assessment not using risk matrices, but instead relying only on the probabilistic characteristics of the occurrence of events. Using the presence of a causal relationship between the layers of the pyramid, we propose an algorithm for the transition of varying degrees of danger of special situations. This algorithm can be used to develop an on-board device that informs the pilot about the dynamics of transitions from one situation to another, representing each emergency situation in a certain color.
      PubDate: Mon, 27 Dec 2021 00:00:00 GMT
       
  • Enhanced Feature Extraction Algorithms Using Oscillatory-Mode Pulsed Eddy
           Current Techniques for Aircraft Structure Inspection

    • Abstract: A review of the existing literature shows that modern pulsed eddy current (PEC) technique for flaw detection in aircraft structure inspection is typically carried out in aperiodic mode. Аt the same time, the unstable characteristic points of the EC signal usually used as informative parameters can restrict the potential of this excitation mode due to significant measurement errors.This article considers an advanced PEC method of NDT based on the oscillatory mode. To obtain the conditions concerned with different modes of EC probe response oscillations, an equivalent scheme of the “testing object – EC probe” system was developed and analyzed. The frequency and attenuation coefficient of natural oscillations are proposed as the informative parameters of the probe signals. The obtained mathematical model of the probe signals allows for the dependence of proposed signal parameters on the characteristics of the testing object to be evaluated.Herein, we first develop algorithmic software for determining and analyzing the discrete amplitude and phase characteristics of PEC NDT signals based on the simulation results. The errors of the natural frequency oscillations and the attenuation coefficient determination as well as the optimal time for its determination are analyzed in order to minimize the possible errors. Next, the proposed informative parameters are experimentally investigated using a set of specimens. The obtained results confirm the possibility of the proposed methodology to enhance the inspection procedures related to the electrical conductivity and geometric parameters measurements as well as the detected defect sizing.
      PubDate: Fri, 08 Oct 2021 00:00:00 GMT
       
  • Numerical Simulation of the Exit Temperature Pattern of an Aircraft Engine
           Using a Temperature-Dependent Turbulent Schmidt Number

    • Abstract: This paper presents a numerical simulation for predicting the combustor exit temperature pattern of an aircraft engine, developed using the commercial fluid simulation software Ansys Fluent, which assumes a shape probability density function for the instantaneous chemistry in the conserved scalar combustion model and the standard k-ε model for turbulence. We found the compliance of the radial and circumferential non-uniformities of the exit temperature with the experimental data to be insufficient. To achieve much more accurate result, the mixing intensity was enhanced with respect to the initial calculation due to using the reduced value of the turbulent Schmidt number Sc. Numerical simulation was performed for values of the turbulent Schmidt number from Sc = 0.85 (default) up to Sc = 0.2, with results confirming the reduction of radial and circumferential non-uniformities of exit temperature. However, correlation between radial and circumferential non-uniformities is not admissible for these cases. Therefore, we propose to use a temperature-dependent formulation of the turbulent Schmidt number Sc, accounting for the increase in Sc number with increasing gas temperature. A user defined function (UDF) was used to implement the Sc number temperature dependence in Ansys Fluent. The numerical results for the proposed Schmidt number Sc temperature dependence were found to be in acceptable agreement with the experimental data both for radial and circumferential non-uniformities of the exit temperature pattern.
      PubDate: Fri, 08 Oct 2021 00:00:00 GMT
       
 
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