Refine Your Search

Search Results

Technical Paper

Highly Efficient Civil Aviation, Now via Operations: AAR & 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

Towards Two 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 (fuel pump, oil pump, engine actuation) will be replaced by the 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 engine and aircraft.
Technical Paper

A Study of Cycle-to-Cycle Flow Variations in a Small Spark-Ignition Engine at Low Throttle Opening

2018-10-30
2018-32-0035
Cycle-to-cycle flow variations significantly influence the combustion variations from one cycle to the next, particularly at low operating loads in small spark-ignition engines. Hence in the present work, cycle-to-cycle flow variations are analyzed at low throttle opening of 25% in a small spark-ignition engine using particle image velocimetry (PIV) technique. Experiments are conducted in an optically accessible single-cylinder, port-fuel-injection engine (volume: 110 cm3) at 1200 rpm engine speed. Images are captured at different crank angle positions during both intake and compression strokes over a tumble measurement plane bisecting the intake and exhaust valves, and processed using cross-correlation method to obtain the instantaneous velocity fields considering 200 image pairs at each crank angle position considered.
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. Subsequent extracted heat is then transferred to ram air through downstream heat exchanger/s. 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 compared to the LCS, utilizes cabin air as the coolant which is in turn supplied using the electric Environmental Control System (ECS) within the MEA. The AACS consist 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.
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

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.
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

An Integrated Approach to Model Based Engineering with SysML, AADL and FACE

2018-10-30
2018-01-1942
Multiple model-based engineering (MBE) frameworks have emerged to cover the many requirements for the engineering of avionics systems: from early requirement capture to the final system and embedded software generation, through refinement and V&V activities. In this paper, we consider the SysML, AADL and FACE standards. They are promoted by different standardization bodies, with different objectives. We note they are often seen as competitive, while we argue it is the opposite: there is a potential for a synergistic coupling. To date, no complete open evaluation on the feasibility of such capability has been done. In this paper, we present one workflow that illustrates the joint use of SysML, AADL and FACE. We consider a basic flight control system to exercise the proposed process and gateways between the three notations.
Technical Paper

Modulation Limit Based Control Strategy for More Electric Aircraft Generator System

2018-10-30
2018-01-1937
Vector based control strategies have been extensively employed for drive systems, and in recent times to the More Electric Aircraft (MEA) generator based systems. The control schemes should maintain the bus voltage and adhere to the generator system voltage and current limits throughout a wide speed range. Typically, the current limit is prioritised first due to ease of implementation and simple control structure. As a result, the voltage limit can be exceeded due to change in operating conditions or disturbance factors. In flux weakening regions, this may affect the controllability of the power converter and lead to generator system instability. In this paper, an alternative control strategy has been investigated to address this drawback. The proposed control scheme refers to the modulation index limit which is the ratio between the power converter input and output voltages as the voltage limit.
Technical Paper

Model-Based Systems Engineering Methodology for Implementing Networked Aircraft Control System on Integrated Modular Avionics – Environmental Control System Case Study

2018-10-30
2018-01-1943
Integrated modular avionics (IMA) architectures host multiple federated avionics applications on a single platform and provide benefits in terms of size, weight, and power, which, however, leads to increased complexity, especially during the development process. To cope efficiently with the high level of complexity, a novel, structured development methodology is required. This paper presents a model-based systems engineering (MBSE) development approach for the so-called “distributed integrated modular architecture” (DIMA). The proposed methodology adapts the open-source Capella tool, based on the Architecture Analysis & Design Integrated Approach (ARCADIA) methodology, to implement a complete design cycle, starting with requirements captured from the aircraft level to streamline the development, culminating in the integration of an avionics application into an ARINC 653 platform.
Technical Paper

Safety Analysis of an Airship that Loses Buoyant Gas from the Hull

2018-10-30
2018-01-1954
This study investigates the physical phenomena that affect a high-altitude airship in the presence of lifting gas losses from the hull. General atmospheric thermodynamics and basic physical principles are adopted to describe the behavior of an airship with envelope failures that generate buoyant gas dispersion or depressurization phenomena. Overpressure that could grant to maintain some controllability during a large part of the descent is assessed by mean of the thermodynamic model of the envelope in the presence of gas losses. An optimization of the inflation parameters is provided and the conditions for avoiding dangerous crashes on the ground and the potential recovery of a damaged vehicle, people and its payload. In particular, the requirements for a slow depressurization is computed by the equilibrium with the atmosphere and then how can it be possible to sustain controlled navigation are determined.
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. Even if it is a marginal contributor to today global GHG emissions (less than 3%), the increasing mobility of people is determining a continuous increase of air traffic with an annual rate of growth around 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 also deals with increasing maintenance and safety issues; 4. the dependence on fossil fuels which deals strictly with areas which are characterized by significant problems of geopolitical instability and oscillations of prices.
Technical Paper

Anomaly Based Intrusion Detection for an Avionic Embedded System

2018-10-30
2018-01-1941
This paper firstly describes the challenges raised by the introduction of Intrusion Detection Systems (IDS) in avionic systems. In particular, we discuss some specific characteristics of such systems and the advantages and limitations of signature-based and anomaly-based techniques in an avionics context. Based on this analysis, a framework is proposed to integrate a Host-based Intrusion Detection System (HIDS) in the general Integrated Modular Avionics (IMA) development process, which fits avionic systems constraints. The proposed HIDS architecture is composed of three modules: anomaly detection, attack confirmation, and alert sending. To demonstrate the efficiency of this HIDS, an attack injection module has also been developed. The overall approach is implemented on an IMA platform running a cockpit display function, to be representative of embedded avionic systems.
Technical Paper

Simulation Optimization of the NASA Mars Fuel In-Situ Resource Utilization and Its Infrastructure

2018-10-30
2018-01-1963
The National Aeronautics and Space Administration’s (NASA) current objectives include expanding space exploration and planning a manned expedition to Mars. In order to meet the latter objective, it is imperative that humans generate their own products by harnessing space resources, a process referred to as In-Situ Resource Utilization (ISRU). ISRU will enable NASA to reduce both payload mass and mission cost by reducing the number of consumables required to be launched from Earth. The discrete-event simulation discussed focuses primarily on one ISRU system, the production of fuel for a return trip to Earth by utilizing Mar’s atmosphere and regolith. This ISRU system primarily uses autonomous rovers for exploration, excavation, processing of Mar’s regolith to produce fuel, and disposal of the processed regolith. This study explores individual rover and component requirements including rover speeds, travel distances, functional periods, charging, and maintenance times.
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

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

Lessons Learned in Inter-Organization Virtual Integration

2018-10-30
2018-01-1944
The SAE AS2C Standard AS5506C Architecture Analysis and Description Language (AADL) is a modeling language for predictive analysis of real-time software reliant, safety and cybersecurity critical systems that provides both the precision of formal modeling and the tool-agnostic freedom of a text-based representation. These traits make AADL ideal for virtual integration, a process that enables early detection of integration defects through model integration of software, computer hardware, and interacting physical devices. AADL supports multiple domains of architectural analysis such as timing, latency, resources, safety, scheduling, and cybersecurity. Adventium Labs conducted an exercise to determine the applicability of software engineering practices (e.g., continuous integration (CI), application programming interface (API) sharing, test driven development (TDD)) to the AADL-based Architecture Centric Virtual Integration Process (ACVIP).
Technical Paper

A Methodology for Formal Requirements Validation and Automatic Test Generation and Application to Aerospace Systems

2018-10-30
2018-01-1948
Automation on Validation and Verification (V&V) leveraging Formal Methods, and in particular Model Checking, is seeing an increasing use in the Aerospace domain. In recent years, Formal Methods have been used to verify systems and software and its correctness as a way to augment traditional methods relying on simulation and testing. Recent updates to the relevant Aerospace regulations (e.g. DO178C, DO331 and DO333) now have explicit provisions for utilization of models and formal methods. In a previous paper a compositional methodology for the verification of Aerospace Systems has been described with application to Electrical Power Generation and Distribution Systems. In this paper we present an expansion of the previous work in two directions. First, we describe the application of the methodology to the validation of Proximity Sensing Systems (PSS) requirements showing the effectiveness of the method to a new aerospace domain.
Technical Paper

Novel Framework Approach for Model-Based Process Integration from Requirements to Verification Demonstrated on a Complex, Cyber-Physical Aircraft System

2018-10-30
2018-01-1947
This paper presents a demonstrator developed in the European CleanSky2 project MISSION (Modelling and Simulation Tools for Systems Integration on Aircraft). Its scope is the development towards a seamless integrated, interconnected toolchain enabling more efficient processes with less rework time in todays, highly collaborative aerospace domain design applications. The demonstration described here, consists of an open, modular and multitool platform implementation, using specific techniques to achieve fully traceable (early stage) requirements verification by virtual testing. The most promising approach is a model based integration along the whole process from requirements definition to the verified, integrated (and certified) system. Extending previous publications in this series, the paper introduces the motivation and briefly describes the technical background and a potential implementation of a workflow suitable for that target.
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.
X