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Technical Paper

Nearfield Analysis of Low Speed Flow over a Dielectric Barrier Discharge Device for Enhancement of Small UAV Aerodynamics

2018-10-30
2018-01-1953
As unmanned aerial vehicle applications continue their rise in popularity in the public and private sectors, there is an increasing demand in many cases for smaller, more efficient low speed unmanned aerial vehicles (UAVs). Although the primary drivers for the continued performance improvement of smaller UAV platforms tend to be in the areas of electronics miniaturization and improved energy storage, aerodynamics, particularly in the low Reynolds number regime, still have a significant role in the overall performance enhancement of small UAVs. This paper focuses on the study of the nearfield aerodynamic effects of a low-power active flow enhancement technique known as dielectric barrier discharge (DBD) in very low speed/low Reynolds number flows most closely associated with small and micro unmanned aerial vehicles.
Technical Paper

Development of a Climate and Altitude Simulation Test Bench for Handheld Power Tools

2018-10-30
2018-32-0033
A climate and altitude conditioning test bench was developed at the Institute of Energy Efficient Mobility (IEEM) of Karlsruhe University of Applied Sciences to evaluate the overall sustainability of using innovative biofuels in handheld power tools such as chainsaws, trimmers and blowers under any typical operating condition worldwide. The 6 m3 hermetically sealed and thermally insulated test chamber is large enough to fit the entire power tool. A two-stage refrigeration system with intake air drying and electric heating allows for realistic temperature conditions to be set in the test chamber, ranging from arctic cold to tropical heat (-28 to 45 °C). Altitudes of up to 3500 m above sea level can be simulated using a throttle valve at the inlet of the chamber and a pressure-controlled rotary screw compressor positioned downstream the test chamber outlet.
Technical Paper

Environmental and Sustainability Aspects of an Aviation Auxiliary Power Unit Analyzed with the Aid of Exergy

2018-10-30
2018-32-0071
During the past decade environmental and sustainability issues have become major problems to overcome since they have caused regional and global consequences. This paper discusses the environmental and sustainability aspects of Gas Turbine (GT) based aviation Auxiliary Power Unit (APU) analyzed with the aid of exergy. Exergy analysis is a potential tool to determine exergy destructions and losses and their true magnitudes and exact locations. In this study some exergy based parameters such as: exergetic efficiency, waste exergy ratio, exergy recoverability ratio, exergy destruction ratio, environmental impact factor, and exergetic sustainability index are proposed and investigated. Cycle operating parameters such as compressor-pressure-ratio (rp,c), Turbine Inlet Temperature (TIT) have been chosen for analysis of the gas turbine cycle based APU. Mathematical modeling of the cycle has been done and the same has been coded in MATLAB.
Technical Paper

The Distributed Simulation of Intelligent Terrain Exploration

2018-10-30
2018-01-1915
In this study we consider the coordinated exploration of an unfamiliar Martian landscape by a swarm of small autonomous rovers, called Swarmies, simulated in a distributed setting. With a sustainable program of return missions to and from Mars in mind, the goal of said exploration is to efficiently prospect the terrain for water meant to be gathered and then utilized in the production of rocket fuel. The rovers are tasked with relaying relevant data to a home base that is responsible for maintaining a mining schedule for an arbitrarily large group of rovers extracting water-rich regolith. For this reason, it is crucial that the participants maintain a wireless connection with one another and with the base throughout the entire process. We describe the architecture of our simulation which is composed of HLA-compliant components that are visualized via the Distributed Observer Network tool developed by NASA.
Technical Paper

Multi-level Modeling Methodology for Aircraft Thermal Architecture Design

2018-10-30
2018-01-1910
This paper proposes a new methodology to conduct thermal analysis in the conceptual phase of the aircraft development process. Traditionally, thermal analysis is conducted after the system architecture has already been defined. The aircraft system thermal environment evaluation may lead to late design changes that can have a significant impact on the development process. To reduce the risk of late design changes, thermal requirements need to be defined and validated in the conceptual design phase. This research paper introduces a novel multi-level modeling strategy based on a bottom-up approach. It proposes an automatic geometrical simplification procedure for Computational Fluid Dynamic (CFD) analysis, a methodology for the generation of analytical correlations based on highly detailed methods, and a thermal risk assessment approach based on dimensionless numbers.
Technical Paper

The Fault-Augmented Approach for the Systematic Simulation of Fault Behavior in Multi-Domain Systems in Aerospace

2018-10-30
2018-01-1917
A library for modelling faults in multi-domain physical systems is introduced. The library is based on the simulation of fault effects on the system’s behavior. The motivation of how and why to model faults systematically as well as a description of the Modelica®-based library structure with a wizard supporting the semi-automatic augmentation process of faults are outlined. The fault types are classified into continuous and discrete with dedicated type definitions. The application of the Fault library is exemplified in the field of aerospace electrohydraulic actuator. The actuator is equipped with hydromechanical, electrical and digital systems for mitigating failures, which should be tested at an early stage of design. To perform the tests, a multi-domain, dynamic system model is created, wherein failures are systematically simulated using a special approach for fault augmentation.
Technical Paper

Reliability Case Analysis of an Autonomous Air Cooling System (AACS) for Aerospace Applications

2018-10-30
2018-01-1916
Current More Electric Aircraft (MEA) utilize Liquid Cooling Systems (LCS) for cooling on-board power electronics. In such LCS, coolant pipes around the structure of the aircraft are used to supply water glycol based coolant to sink heat from power electronics and other heat loads in the electronic bay. The extracted heat is then transferred to ram air through downstream heat exchangers. This paper presents a reliability examination of a proposed alternative Autonomous Air Cooling System (AACS) for a twin engine civil MEA case study. The proposed AACS utilizes cabin air as the coolant which is in turn supplied using the electric Environmental Control System (ECS) within the MEA. The AACS consists of electrical blowers allocated to each heat load which subsequently drive the outflow cabin air through the heat sinks of the power electronics for heat extraction. No additional heat exchanger is required after this stage in which the heated air is directly expelled overboard.
Technical Paper

Feedback on Application of MBSE to an Avionics Subsystem

2018-10-30
2018-01-1922
In avionics domain, currently most engineering efforts and costs come from integration, verification and validation activities. Each error found on requirements during product verification or validation requires a full engineering cycle to manage the change: impact analysis, design, realization, integration, verification and validation again. Hence, ensuring early and continuous validation of requirements in the engineering life cycle, becomes more and more crucial. In this paper, a Model-Based Systems Engineering (MBSE) approach is proposed. The proposed approach relies on SysML models and is composed of modelling tasks to capture requirements and to structure functional interfaces and functions. This approach has been applied in the frame of SAE ARP4754A aerospace recommended practices.
Technical Paper

Analysis of the Effects of Modeling Depth and Parameter Uncertainties on the System Behavior of a Multifunctional High Lift Actuation System

2018-10-30
2018-01-1918
Modeling and simulation have become an important aspect of the design and development process of aircraft systems. During the design of high lift actuation systems for example, the dynamic loads in the transmission are estimated by simulation. Nevertheless huge development efforts and financial resources are still invested in physical testing. These integration and testing phases take place at a late stage in the design process. Therefore, identified malfunctions and development errors lead to undesired iterations and thus to high costs as well as to an increased development time. This issue is emphasized as system complexity is rises continuously in conjunction with an increase in the number of interconnections and functionality. Hence, early and continuous virtual testing activities on the overall system level become increasingly important.
Technical Paper

Highly Efficient Civil Aviation, Now via Operations - AAR and Challenges

2018-10-30
2018-01-1925
Global civil aviation growth at 5+% yearly poses extreme environmental challenges. Advances have appeared gradually through improved aerodynamic shapes, using carbon fibres, and enhanced engines; however, as these technologies mature, direct efficiency advances require increasing effort. Often Passenger convenience is forgotten e.g. the long-range air traffic has developed on hub-spoke basis implying extra feeder flights, transit passenger inconveniences, capacity issues. Efficiency metrics emphasize “Why, How & What”, with an understanding of the range sensitivities, operational concepts and performance goals via the important “X-factor”. For given range, current aircraft are “greener” than previous generations. Medium range aircraft s are always greener than those for short or long ranges. However, currently, the major trend is for the latter: twin-aisle A350, A380, B787, B777X (10+% payload, 40+% fuel to MTOW).
Technical Paper

Development of the Multi-Resolution Modeling Environment through Aircraft Scenarios

2018-10-30
2018-01-1923
Multi-Resolution Modeling (MRM) is one of the key technologies for building complex and large-scale simulations using legacy simulators. MRM has been developed continuously, especially in military fields. MRM plays a crucial role to describe the battlefield and gathering the desired information efficiently by linking various levels of resolution. The simulation models interact across different local and/or distance area networks using the High Level Architecture (HLA) regardless of their operating systems and hardware. The HLA is a standard architecture developed by the US Department of Defense (DoD) and is meant to create interoperability among different types of simulators. Therefore, MRM implementations are very dependent on Interoperability and Composability. This paper summarizes the definition of MRM-related terminology and proposes a basic form of MRM system using Commercial Off-The-Shelf (COTS) simulators and HLA.
Technical Paper

Challenges of Digital Twin in High Value Manufacturing

2018-10-30
2018-01-1928
Digital Twin (DT) is a dynamic digital representation of a real-world asset, process or system. Industry 4.0 has recognised DT as the game changer for manufacturing industries in their digital transformation journey. DT will play a significant role in improving consistency, seamless process development and the possibility of reuse in subsequent stages across the complete lifecycle of the product. As the concept of DT is novel, there are several challenges that exist related to its phase of development and implementation, especially in high value manufacturing sector. The paper presents a thematic analysis of current academic literature and industrial knowledge. Based on this, eleven key challenges of DT were identified and further discussed. This work is intended to provide an understanding of the current state of knowledge around DT and formulate the future research directions.
Technical Paper

Transient Stability Analysis of DC Solid State Power Controller (SSPC) for More Electric Aircraft

2018-10-30
2018-01-1927
The solid state power controller (SSPC) is one of the most important power electronic components of the aircraft electrical power distribution (EPS) systems. This paper presents an architecture of the DC SSPC and provides the mitigation techniques for transient voltage overshoot during its turn-off. The high source side inductance carries breaking current (9xnominal current) just before turnoff and induces large voltage transient across the semiconductor devices. Therefore, the stored inductive energy needs to be dissipated in order to prevent semiconductor switches from over-voltage/thermal breakdown. Three different transient voltage suppression (TVS) devices to reduce voltage stress across switches are included in the paper for detail study. The comprehensive comparison of the TVS devices is presented. In addition, the thermal impact of the TVS devices on the semiconductor switches is also analyzed.
Technical Paper

Improving Manufacturing Efficiencies through Industry 4.0 Technologies in Aerospace

2018-10-30
2018-01-1929
1 In the age of 4th industrial revolution, operational and information technologies are increasingly getting converged to help organizations improve their topline through new innovative products and services, and improve bottom line by improving efficiencies. This transformation is driven by convergence of many advanced technologies such as advanced sensor and communication technologies, big data, advanced analytics, Artificial Intelligence (AI), robotics, additive manufacturing, virtual and augmented reality (VR/AR). Enterprises digitization journey continues to adopt advanced technologies through multi-pronged approach to achieve their near-term and long-term goals. This paper summarizes Industry 4.0 journey, its relevance and applications to aerospace.
Technical Paper

Power Dissipation Optimization for Solid State Power Control Modules in the Aircraft Secondary Power Distribution System

2018-10-30
2018-01-1930
In the last two decades, an aerospace industry trend in the secondary power distribution concept has been dominated by power electronics technology which includes power converters and Power Control Modules based on Solid State Power Control (SSPC) switching elements. These Power Control Modules, grouped around microprocessor based controllers and combined in a single electronic chassis, have become a backbone of electrical power distribution systems on all major commercial and military transport aircraft. Due to the resistive properties of the semiconductor-based SSPC devices, whose behaviors can be described as nonlinear functions of ambient operating temperature, power distribution system integration with SSPCs is challenged and heavily affected by operating temperatures and power dissipation limits. Although aircraft compartments where Power Control Modules are located are considered temperature and pressure controlled, high ambient operating temperatures are possible and expected.
Technical Paper

Definitions of Test Conditions for High Voltage Aerospace Systems Using the IAGOS Atmospheric Dataset

2018-10-30
2018-01-1931
Aerospace electrical systems are continuing to increase their voltage levels to meet the on-board power demands of more-electric aircraft (MEA) where hydraulic and pneumatic systems are replaced with electrical equivalents. This trend will only continue as hybrid and all- electric aircraft are developed. These higher power demands require the use of higher voltages and as such it is essential to explore the behaviour of the insulation system in the aerospace environment. This insulation must operate in an environment where the operating temperatures range from 250°C to -65°C, the air pressure is around one tenth of that at ground level and where the levels of humidity and ozone vary rapidly. Understanding the impact of these variables on aircraft high voltage insulation systems is crucial in predicting their behaviour and lifetime.
Technical Paper

Energetic, Environmental and Range Estimation of Hybrid and All-Electric Transformation of an Existing Light Utility Commuter Aircraft

2018-10-30
2018-01-1933
Today it is necessary to face the energetic, environmental, and safety-related issues of a significant industrial sector such as aeronautic one. It is a marginal contributor to today global GHG emissions (less than 3%), In any case, the associated impacts grows with the increase of air traffic with annual rate 5%. Consequently, aviation will need to face four fundamental problems for the future: 1 the overall impact of aviation is expected to grow up to 10÷15% of global GHG emissions by 2050; 2 the emissions of pollutants by commercial aviation affects the fragile atmospheric layers in the low stratosphere; 3 the increasing age of the flying fleet deals with increasing maintenance and safety issues; 4 the dependence on fossil fuels relates to problems of geopolitical instability and consequence volatility of prices. Substantial innovations are expected for both reducing energy consumption and environmental impacts of aviation and reducing the age of the fleets.
Technical Paper

DC Arc Fault Detection Methods in MEA Distribution Systems

2018-10-30
2018-01-1934
Direct current (DC) for primary power distribution is a promising solution that is being explored by aircraft system integrators for MEA applications to enable the paralleling of non-synchronized engine off-take generators, and to enable the reduction of energy conversion stages required to supply electronically actuated loads. However, a significant challenge in the use of DC systems is the reliable detection of arc faults. Arcing presents a significant fire risk to aircraft and their presence can result in critical system damage and potentially fatal conditions. Series arc faults in DC systems are particularly challenging to detect as the associated reduction in system current eliminates the use of conventional overcurrent and current differential methods for fault detection. This paper provides an overview of series arc faults in DC systems and presents both simulation and hardware results to illustrate key trends, characteristics and discriminating features.
Technical Paper

Towards Dual and Three-Channel Electrical Architecture Design for More-Electric Engines

2018-10-30
2018-01-1935
In recent years, the More-Electric Aircraft (MEA) concept has undergone significant development and refinement, striving towards the attainment of reductions in noise and CO2 emissions, increased power transmission efficiency and improved reliability under a range of flight scenarios. The More-Electric Engine (MEE) is increasingly being seen as a key complementary system to the MEA. With this concept, conventional engine auxiliary systems (i.e. fuel pumps, oil pumps, actuators) will be replaced by electrically-driven equivalents, providing even greater scope for the combined aircraft and engine electrical power system optimisation and management. This concept, coupled with extraction of electrical power from multiple engine spools also has the potential to deliver significant fuel burn savings. To date, single or dual channel electrical power generation and distribution systems have been used in engines and aircrafts.
Technical Paper

Dynamic Stability Analysis of High-Speed Traction Drive CVT for Aircraft Power Generation

2018-10-30
2018-01-1936
The traction-drive integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators mounted on Japanese military aircraft. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24000 rpm, that is, a 400 Hz AC power supply. To cope with recent trends of more electric aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over other transmissions. The torque on the half-toroidal variator is transmitted through multiple power rollers. The equal load sharing among power rollers is typically controlled by a mechanical hydraulic feedback system, whose stability is one of the main issues for the high-speed traction-drive CVT. Previous studies have shown that insufficient damping and stiffness of the mechanical hydraulic feedback system cause self-induced vibration.
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