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Abstract Inspection of Composite panels is vital to the assessment of their ability to be fit for purpose. Conventional methods such as X-ray CT and Ultrasonic scanning can be used, however, these are often expensive and time consuming processes. In this paper we investigate the use of off-the-shelf Non-Destructive Test, NDT, equipment utilizing Fringe projection hardware and open source software to rapidly evaluate a series of composite panels. These results are then verified using destructive analysis of the panels to prove the reliability of the rapid NDT methods for use with carbon composite panels. This process allows us to quickly identify regions of geometric intolerance or formed defects without the use of expensive sub-surface scanning systems, enabling a fast and cost effective initial part evaluation system. The focus of this testing series is on 6mm thick pre-preg carbon-epoxy composite laminates that have been laid up using AFP and formed using TRF.

Abstract The use of nanomaterials and nanostructures have been revolutionizing the advancements of science and technology in various engineering and medical fields. As an example, Carbon Nanotubes (CNTs) have been extensively used for the improvement of mechanical, thermal, electrical, magnetic, and deteriorative properties of traditional composite materials for applications in high-performance structures. The exceptional materials properties of CNTs (i.e., mechanical, magnetic, thermal, and electrical) have introduced them as promising candidates for reinforcement of traditional composites. Most structural configurations of CNTs provide superior material properties; however, their geometrical shapes can deliver different features and characteristics. As one of the unique geometrical configurations, helical CNTs have a great potential for improvement of mechanical, thermal, and electrical properties of polymeric resin composites.

Abstract This study discusses the experimental investigation on WEDM of combustor material (i.e., nimonic 263). Experimentation has been executed by varying pulse-on time (Ton), pulse-off time (Toff), peak current (Ip), and spark gap voltage (Sv). Material removal rate (MRR), surface roughness (SR), and wire wear rate (WWR) are employed as process performance characteristics. Experiments are designed as per the box-Behnken design technique. Parametric optimization has also been performed using response surface methodology. Besides this, field-emission scanning electron microscope (FE-SEM) and an optical microscope are utilized to characterize WEDMed and worn-out wire surfaces. It is observed that both surfaces contain micro-cracks, craters, spherical droplets, and a lump of debris. Furthermore, the mechanism of recast layer formation has been critically evaluated to apprehend a better understanding of the technique. The key features of the experimental procedure are also highlighted.

Abstract Transient numerical simulations are conducted over a NACA 0012 airfoil with triangular protrusions at a Reynolds number (Re) of 100000 using the γ-Reθ transition Shear Stress Transport (SST) turbulence model. Protrusions of heights 0.5%c, 1%c, and 2%c are placed at one of the three locations, viz, the leading edge (LE), 5%c on the suction surface, and 5%c on the pressure surface, while the angle of attack (AOA) is varied between 0° and 20°. Results obtained from the time-averaged solution of the unsteady Navier-Stokes equation indicate that the smaller protrusion placed at 5%c on the suction surface improves the post-stall lift coefficient by up to 59%, without altering the pre-stall characteristics. The improvement in time-averaged lift coefficients comes with enhanced flow unsteadiness due to vigorous vortex shedding.

Abstract The Naval Nose Landing Gear (NLG) structural assembly consists of components with complex structural geometry and critical functionalities. The landing gear components are subjected to high static and dynamic loads, so they must be appropriately designed, dimensioned, and made by materials with mechanical characteristics that meet high strength, stiffness, and less weight requirements. This article contributes to the shape, size, and material optimization for the NLG of a supersonic naval aircraft for the estimated static loads. The estimated modal frequency values of the NLG assembly using Finite Element Analysis (FEA) software were compared with available Ground Vibration Test data of an aircraft to literally prove the accuracy and suitability of finite element (FE) model that can be used for any further analysis.

Abstract It is reasonable to use a two-phase heat transfer loop (TPL) in a thermal control system (TCS) of spacecraft with large heat dissipation. One of the key elements of TPL is a heat-controlled accumulator (HCA). The HCA represents a volume which is filled with vapor and liquid of a single working fluid without bellows. The pressure in a HCA is controlled by the heater. The heat and mass transfer processes in the HCA can proceed with a significant nonequilibrium. This has implications on the regulation of TPL. This article presents a mathematical model of nonequilibrium heat and mass transfer processes in an HCA for microgravity conditions. The model uses the equations of mass and energy conservation separately for the vapor and liquid phases. Interfacial heat and mass transfer is also taken into account. It proposes to use the convective component k for the level of nonequilibrium evaluation.

Abstract ERRATUM

Abstract From the fact that a propulsor consumes less power for a given thrust if the inlet air is slower, simulations are conducted for a propulsor imposed behind an airfoil as ideal boundary layer ingestion (BLI) propulsor to stand on the benefits of this configuration from the point of view of power and efficiency and to get a closer look on the mutual interaction between them. This interaction is quantified by the impact on three main sets of parameters, namely, power consumption, boundary layer properties, and airfoil performance. The position and size of the propulsor have great influence on the flow around the airfoil. Parametric studies are carried out to understand their influence. BLI propulsor directly affects the power saving and all of the pressure-dependent parameters, including lift and drag. For the present case, power saving reached 14.4% compared to the propeller working in freestream.

Abstract The range of an aircraft is determined by the amount of energy that its batteries can store. Today, larger batteries are used to increase the range of electric vehicles, although energy efficiency decreases as the weight of the vehicles increases. Among the elements, lithium (Li) is the lightest and has the highest electrochemical potential. Therefore, the use of Li-ion batteries is recommended for hybrid aircraft. In addition, Li-ion batteries are the most common type of battery that is used in portable electronic devices such as smartphones, tablets, and laptops. However, Li-ion batteries may explode due to temperature. Therefore, the thermal analysis of Li-ion batteries was investigated both experimentally and numerically. Li-ion batteries were connected in series (the number is 9). Noboru’s theory of heat generation was discussed in the estimation of energy data.

Abstract Inline piston pumps are extensively used in aircraft hydraulic systems. They can be found in engine-driven large-sized hydraulic pumps and zonal electric motor-driven mid-small sized pumps. Inline piston pumps are positive displacement pumps with variable volumetric flow controls. Positive displacement pumps can provide a variable flow rate over a wide range of suction pressures. Aircraft fly at high altitudes, and therefore these pumps have to work in extreme conditions such as low atmospheric pressure, low temperature. At low inlet pressures, the pump is highly susceptible to cavitation, i.e., insufficient filling capacity. The pressure below which pump flow rate drops drastically is known as critical inlet pressure. Extensive research has been carried out to study cavitation in inline piston pumps.

Abstract The paper presents a complete description of the design and manufacturing of a Carbon Fiber/epoxy mold with an embedded Carbon Fiber resistor heater, and the mold performances in terms of its surface temperature distribution and thermal deformations resulting from the heating. The mold was designed for manufacturing aileron skins from Vacuum Bag Only prepreg cured at 135°C. The glass transition temperature of the used resin-hardener system was about 175°C. To ensure homogenous temperature of the mold working surface in the course of curing, the Carbon Fiber heater was embedded in a layer of a highly heat-conductive cristobalite/epoxy composite, forming the core of the mold shell. Because the cristobalite/epoxy composite displayed much higher thermal expansion than CF/epoxy did, thermal stresses could arise due to this discrepancy in the course of heating.

Abstract The supersession of metallic alloys with lightweight, high-strength composites is popular in the aircraft industry. However, aviation electronic enclosures for large format batteries and high power conversion electronics are still primarily made of aluminum alloys. These aluminum enclosures have attractive properties regrading structural integrity for the heavy internal parts, electromagnetic interference (EMI) suppression, electrical bonding for the internal cells, and/or electronics and failure containment. This paper details a lightweight carbon fiber composite chassis developed at Meggitt Sensing Systems (MSS) Securaplane, with a copper metallic mesh co-cured onto the internal surfaces resulting in a 50% reduction in weight when compared to its aluminum counterpart. In addition to significant weight reduction, it provides equal or improved performance with respect to EMI, structural and flammability performance.

Abstract The article considers one of the possible mechanisms of loading the solidity of a cylindrical metal composite high-pressure vessel (MC HPV). This mechanism manifests itself as delamination of a thin-walled metal shell (liner) from a more rigid composite shell causing local buckling. A similar effect can be detected in the manufacturing process of MC HPV, when the composite shell is formed by winding with tension a carbon fiber-reinforced plastic tape on the liner. Pressure transfer from the composite shell to the liner is carried out by the method of temperature analogy, that is, by cooling the composite shell, thermally insulated from the liner. To solve the problem of externally confined liner local buckling an approach is proposed, which is based on three points: the introduction of local technological deviations inherent in actual structures, the determination of the general stress-strain state, and a real-time deforming.

Abstract The purpose of this study is to examine the phenomenon of Dynamic Particle Generation in lubricating greases that are used in a variety of critical Aerospace mechanisms. Particle Generation occurs in bearings, ball screws, and other mechanical devices where dynamic conditions are present. This should not be confused with outgassing as particle generation is unrelated to the pressure effects on a system. This is a critical factor in many systems as particle generation can contaminate systems or processes causing them to fail. These failures can lead to excessive costs, production failure, and equipment damage. In this study, several greases made from Multiplyalkylated Cyclopentane and Perfluoropolyether base fluids were tested to evaluate their particle generation properties. This particle generation phenomenon was studied using a custom test rig utilizing a high precision cleanroom ball-screw to simulate true application conditions.

Abstract Aircraft subsystem development involves various combinations of testing and qualification activities to realize a flight-worthy system. The subsystem needs to be verified for a massive number of customer requirements. Power quality (PQ) testing is also an important testing activity carried out as part of the environmental qualification test. It is intended to verify the functionality of subsystems with various kinds of power disturbances and to determine the ability of a subsystem to withstand PQ disturbances. The subsystem being designed should be reliable enough to handle PQ anomalies. A PQ test results in an enormous amount of data for analysis with millions of data samples depending on the test and can be identified as big data. The engineer needs to analyze each set of test data as part of post-processing to ensure the power disturbances during testing are as per the standard requirements and that the functional performance of the subsystem is met.

Abstract A large amount of heat generated in the engineering compartment in a hovering helicopter may lead to premature degradation of inner skin of its engine cowling and cause serious failure on the engine cowling. This study proposes a solution of improving heat resistance of the helicopter engine cowlings by replacing the currently used intumescent coating with a ceramic coating material, Cerakote C-7700Q. Oven and flame tests were designed and conducted to evaluate the heat resistance of Cerakote C-7700Q. The test results show that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. Based on that, a new painting scheme with C-7700Q implemented was recommended.

Abstract Federal Aviation Administration (FAA)’s 20 years of research and development with 200 unleaded blends and full-scale engine tests on 45 high-octane unleaded blends has not found a “drop-in” unleaded replacement for aviation gasoline (AVGAS) 100 low lead (100LL) fuel. In this study, analysis of compatibility via optimization of Lycoming O-320 engine fuelled with RON 97, RON 98, RON 100, and AVGAS was conducted using the Response Surface Methodology (RSM). Test fuels were compositionally characterized based on Gas Chromatography (GC) analysis and were categorized based on types of Hydrocarbon (HC). Basic fuel properties of fuels in this research were analyzed and recorded. For optimization analysis, engine speed and fuel were considered as the input parameters.

Abstract The numerical analysis of the three-dimensional (3D) flow over a National Advisory Committee for Aeronautics (NACA) 6321 airfoil to evaluate the mass flow rate by using a novel method Improved Blowing and Suction System (IBSS) to control the boundary layer is presented in this study. Analysis is performed based on 3D Reynolds-Averaged Navier-Stokes (RANS) equation with a K-omega SST solver. The aerodynamic performance of the NACA 6321 is analyzed at a Mach number of 0.10 with three different mass flow rates, namely, 0.08 kg/s, 0.10 kg/s, and 0.12 kg/s. From the study, it is seen that when the mass flow rate decreased, the aerodynamics performance also reduced, and the aerodynamic performance improved with the increase in mass flow rate.

Abstract Possible oil contamination of aircraft bleed air is an ongoing operational issue for commercial aircraft. A sensitive and reliable method to detect contamination, especially at very low levels, has been elusive due, in part, to the lack of information about the physical nature of oil that results when entrained in the bleed air by an engine compressor. While it was expected that high shear rates in the compressors would result in very finely dispersed particles, detailed data on the size characteristics of these droplets were not available, making it difficult to develop reliable detection techniques. The goal of the reported research was to collect experimental data to provide this information. The concentration and size distribution of particles were measured for bleed air with different rates of controlled oil contamination under various engine operating conditions.

Abstract Aircraft lift bag is the equipment used for the recovery of an aircraft and is considered as a lifting equipment. Boeing 737 is a domestic aircraft considered for designing this bag. The aircraft lift bag is made of composite material, and the most widely used materials are nylon and neoprene. A composite material is used to make the bag lightweight and easy to handle. For calculation of properties and the engineering constant of the respective composite materials, micromechanics approach is used, in which the method of Representative Volume Element (RVE) is taken into consideration. The loading and boundary conditions are the exact replica of the working conditions. The operation of this bag is completely pneumatic. The stresses induced in the bag are analyzed in finite element software and are compared with the calculated theoretical values. CATIA is used to model the bag, and ABAQUS is used for the finite element calculations.