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A risk-based UAM airspace capacity assessment method using Monte Carlo simulation
Get PDFInspired by risk analysis assistance service and dynamic capacity management service in U-space service, this paper investigates a risk-based UAM airspace capacity assessment method using Monte Carlo simulation for future urban air mobility. The quantitative risk assessment of the flight plan is divided into three parts: the ground / air risks of the flight plan and the mid-air collision risk between UAM. Using the comprehensive risk assessment method, this paper generates several simulation scenarios in the airspace to be evaluated in terms of the type of participants, the presence of the detect and avoid system, and the total number of participants in the airspace, conducts Monte Carlo simulations, and records the simulation data for analysis. Through the analysis of simulation data, it is found that the maximum risk of UAM in airspace increases with the increase of the number of airspace invaders and the total number of UAM. However, the maximum risk of UAM in airspace decreases when the aircraft in airspace contains the detection and avoid system with the same other conditions. Based on simulation data, this paper informatively proposes the concept of a 3D risk surface and a risk-based airspace capacity envelope, using the horizontal surface formed by a specific risk threshold to cut the 3D risk surface to form an airspace capacity envelope, which visually describes the number of aircraft that can be contained in the airspace under a specific risk threshold.2023 IEEE/AIAA 42nd Digital Avionics Systems Conference (DASC
Review of sonic boom prediction and reduction methods for next generation of supersonic aircraft
Get PDFThe reduction of sonic boom levels is the main challenge but also the key factor to start a new era of supersonic commercial flights. Since 1970, a FAA regulation has banned supersonic flights overland for unacceptable sonic booms at the ground, and many research studies have been carried out from that date to understand sonic boom generation, propagation and effects, both on the environment and communities. Minimization techniques have also been developed with the attempt to reduce sonic boom annoyance to acceptable levels. In the last 20 years, the advances in both knowledge and technologies, and companies and institutions’ significant investments have again raised the interest in the development of new methods and tools for the design of low boom supersonic aircraft. The exploration of unconventional configurations and exotic solutions and systems seems to be needed to effectively reduce sonic boom and allow supersonic flight everywhere. This review provides a description of all aspects of the sonic boom phenomenon related to the design of the next generation of supersonic aircraft. In particular, a critical review of the prediction and minimization methods found in the literature, aimed at identifying their strengths, limitations and gaps, is made, along with a complete overview of disruptive unconventional aircraft configurations and exotic active/passive solutions to boom level reduction. The aim of the work is to give a clear statement of state-of-the-art sonic boom prediction methods and possible reduction solutions to be explored for the design of next low-boom supersonic aircraft.European Union funding: 101006742Aerospac
Elastic wave mechanics in damaged metallic plates
Get PDFHuman health monitoring (HHM) is essential for continued daily task execution, as is structural health monitoring (SHM) for structures to ensure the continual performance of their designed tasks with optimal efficiency. The existence of damage in a structure affects its optimal use through stiffness deterioration. Damage of different forms could occur in a structure but have the singular objective of material degradation, leading to its underuse for a task. Guided wave ultrasonics has shown strength in detecting sundry damage in structures, but most of the damage monitored and detected is unfilled with substances. However, some damage could trap and accumulate substances that could hasten material degradation through corrosion activities under favorable conditions, especially in the oil and gas industry. This study used the ultrasonic-guided waves’ pitch–catch inspection technique to identify damage filled with different materials. The assessment was based on the RMSD of the dominant Lamb wave mode’s average maximum amplitude and the response signals’ transmission coefficient (TC). A five-cycle tone burst of excitation signals of different frequencies was created to generate propagating Lamb waves in the structure. The fundamental antisymmetric mode was found to be more sensitive than the fundamental symmetric mode when detecting damage filled with various substances. At 80 kHz, the deviation of the current response signals from the baseline response signals due to different filled substances in the damage was distinct and decreased with increased fluid viscosity. Given that structures in the oil and gas sector are particularly susceptible to substance-induced damage, the outcomes of this study are paramount.Symmetr
Design optimisation of non-axisymmetric exhausts for installed civil aero-engines
Get PDFFuture civil aero-engines are likely to operate with higher bypass-ratios (BPR) than current power-plants to improve propulsive efficiency and reduce specific thrust. This will probably be accompanied by an increase of fan diameter and size of the power plant. Consequently, future configurations are likely to require more close-coupled installations with the airframe due to structural and ground clearance requirements. This tendency may lead to an increase in the adverse installation effects which could be mitigated with non-axisymmetric exhausts. However, due to the prohibitive computational cost, limited regions of the design space have been studied. For this reason, a relatively low-cost design approach for the integrated system is required. The aim of this work is to establish a method to map the non-axisymmetric exhaust design space where the effects of the propulsion system installation are taken into account. The methodology relies on the generation of a design database using inviscid computational fluid dynamics (CFD) methods. This is used to characterise the design space, identify the dominant design parameters and build response surface models for optimisation. The candidate designs that arise from the optimisation are assessed with viscous CFD simulations to assess the aerodynamic mechanisms and performance characteristics. The result is a set of design recommendations for installed configurations with non-axisymmetric exhausts. The method is an enabler for the optimisation of installed propulsion systems and has provided an exhaust design with a 0.7% improvement on net vehicle force relative to an axisymmetric exhaust, for a close coupled configuration where the fan cowl is overlapped with the wing. A reduction in net vehicle force is expected to lead to a similar reduction in cruise fuel burn.Rolls Royce plc.
Cranfield UniversityAerospace Science and Technolog
Resonance mechanism of hydroelastic response of multi-patch floating photovoltaic structure in water waves over stepped seabed
Get PDFThis paper investigates the hydroelastic response of a multi-patch floating photovoltaic (FPV) structure in water waves over a stepped seabed. The resonance conditions and underlying mathematical mechanism of FPV patches are explored based on the linear potential-flow theory and the thin-plate model. An implicit function of the open-water wavelength and the FPV patch's structural wavelength is derived. Resonance conditions occur in the FPV patch when the patch length and structural wavelength (rather than the water wavelength, as commonly believed) satisfy certain proportions. Mathematical derivations are conducted to interpret the value of each proportion. Two resonance conditions are recognized based on the mathematical structure of the solution. The effects of a stepped seabed and adjacent patches on the resonance conditions and hydroelastic behavior of FPV structures are also investigated. For a given stiffness parameter, the resonance conditions of FPV patches are solely determined by the water depth. The distance between adjacent patches does not alter the resonance conditions of each patch. Resonance occurs in the water body between two patches when the ratio of patch distance to water wavelength takes certain proportional values. A resonant water body tends to amplify the oscillation amplitude of both patches. However, when two FPV patches and a constrained water body reach their theoretical resonance conditions at the same time, the oscillation amplitudes of both the seaward patch and the constrained free surface are evidently suppressed. The transmitted waves of an FPV structure are largely determined by the dynamics of the leeward patch.Physics of Fluid
Assessment of novel hybrid treatment wetlands as nature-based solutions for pharmaceutical industry wastewater treatment
Get PDFThis study investigated the use of nature-based solutions for treating real pharmaceutical industry wastewater in Jordan. A pilot-scale hybrid treatment wetland (TW) equipped with local zeolite was employed, comprising a tidal flow TW and a horizontal subsurface flow TW. This system was efficient in treating pharmaceutical wastewater with removal efficiencies of 61.4%, 52.6%, 60.1%, and 61.9% for chemical oxygen demand, total phosphorus, total nitrogen, and NH4+-N, respectively. The final effluent met Jordanian standards for the reuse of treated wastewater in irrigation (Class B). Five pharmaceuticals, namely, enrofloxacin, ciprofloxacin, ofloxacin, lincomycin, and trimethoprim, demonstrated nearly completed removal (93.6–99.9%). Moderated removal performances (59.2–68.2%) were observed for two compounds, flumequine and sulfaquinoxaline. However, three pharmaceuticals, namely, carbamazepine, diclofenac, and sulfadimidine, showed limited removal performances (1.1–20.5%). This study supported the feasibility of using nature-based solutions for treating pharmaceutical wastewater and highlighted that future studies are required to optimize this strategy for removing a broader range of pharmaceuticals.Water and Environment Journa
Dynamic separation minima prediction with collision risk modelling (CRM)
Get PDFIn this paper, we modelled the geometry between 2 proximate aircraft as an oblate-spheroid and obtained a collision risk model based on collision probability. The methodology entails translating the communication, navigation and surveillance error characteristics, and wind uncertainty into the spatial domain of spheroid. Furthermore, we used the collision probability to design a dynamic separation minima based on the parameters of the oblate-spheroid geometry. The results showed that by varying the parameters of the spheroid, allows for a dynamic setting of the separation minima. The collision probability was compared to Monte Carlo simulations as a baseline model. Therefore we proposed a dynamic configuration of the separation minima between aircraft as a function of the collaborative geometry to increase the airspace capacity, especially with great demand from unmanned operations.IEEE/AIAA 42nd Digital Avionics Systems Conference (DASC) 202
Transitioning through the vapour-liquid equilibrium for low energy thermal stripping of ammonia from wastewater: enabling transformation of NH3 into a zero-carbon fuel
Get PDFVacuum thermal stripping permits the recovery of ammonia from wastewater in a concentrated form, which is key to its exploitation in the circular economy, but the latent heat demand for thermal separation remains a critical barrier to exploitation. In this study, we investigate the vapor-liquid equilibrium (VLE) for ammonia-water as a mechanism to enhance recovered ammonia quality and minimise the thermal energy required for ammonia separation. Below the dew point (65 °C at 0.25 bar) a two-phase region of the VLE exists where 48 %wt gas-phase ammonia could be produced (61 °C) compared to only 2 %wt within the stripping region adopted widely in the literature. This was complemented by a 98 % reduction in thermal separation energy, since limited water vaporization can occur when the feed is maintained below the activation energy threshold for bulk evaporation. Operation within this practically unexplored region of the ammonia-water VLE fosters a gas-phase product suitable for energy generation in gas turbines or solid oxide fuel cells. Comparable product quality was achieved using concentrated wastewater, which validated the VLE for design in the presence of a broad range of dissolved gases and volatile inorganic compounds. Rapid desorption of CO2 occurred during vacuum stripping, subsequently increasing pH >9 without the requirement for alkali addition to shift the ammonia-ammonium equilibrium in favor of gaseous ammonia. Consequently, the two-phase region of the VLE defined for vacuum thermal stripping provides a synergistic strategy to mitigate chemical demand, minimise separation energy and recover gas-phase ammonia for zero carbon energy generation, constituting a significant advancement toward the net zero ambitions of the water sector.Engineering and Physical Sciences Research Council (EPSRC): STREAM CDTWater Researc
Enabling UAVs night-time navigation through mutual information-based matching of event-generated images
Get PDFAdvanced Air Mobility is expected to revolutionize the future of general transportation. However, to make it a reality, significant challenges arise requiring technologies to ensure the expected attributes in these scenarios: resilience, robustness, large operational range, high accuracy, low SWaP equipment, and real-time processing. Although existing visual-based navigation solutions for aerial applications provide outstanding results under nominal conditions, their performance is highly constrained by the lighting conditions, making them infeasible for real operations. With the main focus of addressing this limitation, and expanding the current operational range to include extreme low-illuminated environments, this paper presents a solution which leverages one of the most powerful properties of event cameras: their high dynamic range. Thus, data provided by an event camera (also called dynamic vision sensor) is used to estimate the relative displacement of a flying vehicle during night-time conditions. To that end, two different threads running in parallel have been developed: a reference map generator, operating at low frequency, focused on reconstructing a 2-D map of the environment, and a localization thread, which matches, at high frequency, real-time event-generated images against the reference map by applying Mutual Information to estimate the aircraft’s relative displacement.IEEE/AIAA 42nd Digital Avionics Systems Conference (DASC) 202
Microscale electromagnetic actuation of ferrofluid for enhanced cooling efficiency
No full textEfficient cooling solutions can greatly enhance the performance and reliability of electronic systems. Traditional cooling methods have been well-developed, but most are based on not highly efficient cost effective conduction heat exchange. Improving heat exchange efficiency at low cost is a crucial task for all cooling applications. In this paper, we propose a novel method to improve heat exchange efficiency based on ferrofluid, a fluid with ferromagnetic properties, as a coolant. As a result, conduction heat exchange can be easily transformed into convection heat exchange in a passive manner with no additional energy required, significantly increasing cooling efficiency at a relatively low cost. A cooling system using ferrofluid as a coolant is designed and applied to a multi-junction ,or concentrated, photovoltaic and thermal (CPV/T) system through CFD modelling. Novel unsteady flow is generated resulting in higher thermal efficiency. Since ferrofluid is a nanoparticle, the proposed cooling method can be downsized to micro- or nano-scales for potential applications in many new areas.2023 IEEE International Electric Machines & Drives Conference (IEMDC