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Viewing 1 to 30 of 2815
2017-08-29
Journal Article
2017-01-9001
Hermann Ferschitz, Michael Wannemacher, Otto Bucek, Florian Knöbel, Wolfgang Breitfuß
Abstract RTA Rail Tec Arsenal Fahrzeugversuchsanlage GmbH has focused on the simulation of in-flight icing conditions since 2012. Following the successful implementation of the icing conditions specified in EASA CS-25 Appendix C, it was expected that the facility could also be used to simulate the SLD conditions required by EASA CS-25 Appendix O. This paper sets forth theoretical considerations concerning the selection of suitable nozzles and their operation in the existing facility. The transport of large droplets through the contraction nozzle was simulated using a CFD program. The results then served as a basis for deriving secondary droplet breakup. The validations carried out confirm the theoretical considerations and identify potential limits and open research questions.
2017-03-28
Journal Article
2017-01-1512
Fuliang Wang, Zhangshun Yin, Shi Yan, Jia Zhan, Heinz Friz, Bo Li, Weiliang Xie
Abstract The validation of vehicle aerodynamic simulation results to wind tunnel test results and simulation accuracy improvement attract considerable attention of many automotive manufacturers. In order to improve the simulation accuracy, a simulation model of the ground effects simulation system of the aerodynamic wind tunnel of the Shanghai Automotive Wind Tunnel Center was built. The model includes the scoop, the distributed suction, the tangential blowing, the moving belt and the wheel belts. The simulated boundary layer profile and the pressure distribution agree well with test results. The baseline model and multiple design changes of the new Buick Excelle GT are simulated. The simulation results agree very well with test results.
2017-03-28
Journal Article
2017-01-1549
Taro Yamashita, Takafumi Makihara, Kazuhiro Maeda, Kenji Tadakuma
Abstract In recent years, the automotive manufacturers have been working to reduce fuel consumption in order to cut down on CO2 emissions, promoting weight reduction as one of the fuel saving countermeasures. On the other hand, this trend of weight reduction is well known to reduce vehicle stability in response to disturbances. Thus, automotive aerodynamic development is required not only to reduce aerodynamic drag, which contributes directly to lower fuel consumption, but also to develop technology for controlling unstable vehicle behavior caused by natural wind. In order to control the unstable vehicle motion changed by external contour modification, it is necessary to understand unsteady aerodynamic forces that fluctuating natural wind in real-world environments exerts on vehicles. In the past, some studies have reported the characteristics of unsteady aerodynamic forces induced by natural winds, comparing to steady aerodynamic forces obtained from conventional wind tunnel tests.
2017-01-10
Technical Paper
2017-26-0336
Ganesh Liladhar Yewale, Abhishek Tapkire, D Radhakrishna, Popat Shejwal, Kaushal Singh, Gaurav Panchal
Abstract VRDE has developed Wankel type rotary engine to achieve high power output & fuel efficiency for indigenization programme of UAVs. This engine is meeting all performance parameters needed for intended aerial vehicle. This paper describes the testing methodology followed by development engineers to prove the endurance and reliability of UAV engine for airworthiness certification. This paper gives the brief about testing carried out on the Wankel engine, failures faced during endurance testing and their rectification to enhance the life of the engine to achieve hundred test cycle mark. This paper also briefs about the test set up, endurance test cycles simulating the practical operating conditions.
2016-09-27
Technical Paper
2016-01-2123
Matthias Busch, Benedikt Faupel
Abstract The integration of omega stringers to panels made of carbon fiber reinforced plastic (CFRP) by adhesive bonding, which is achieved by baking in an autoclave, must be subject to high quality standards. Failures such as porosity, voids or inclusion must be detected safely to guaranty the functionality of the component. Therefore, an inspection system is required to verify these bonds and detect different kinds of defects. In this contribution, the advantages of a robotic inspection system, which will be achieved through continuous testing, will be introduced. The testing method is the active thermography. The active thermography has major advantages compared with other non-destructive testing methods. Compared to testing with ultrasonic there is no coupling medium necessary, thus testing will be significantly enhanced.
2016-09-27
Technical Paper
2016-01-2145
Ryan Haldimann
Abstract Inspection of fasteners prior to installation is critical to the quality of aerospace parts. Fasteners must be inspected for length/grip and diameter at a minimum. Inspecting the fasteners mechanically just prior to insertion can cause additional cycle time loss if inspection cannot be performed at the same time as other operations. To decrease fastener inspection times and to ensure fastener cartridges contain the expected fastener a system was devised to measure the fastener as it travels down the fastener feed tube. This process could be adapted to inspection of fasteners being fed to the process head of a running machine eliminating the mechanical inspection requirement and thus decreasing cycle time.
2016-09-20
Technical Paper
2016-01-2039
Prashant S. Vadgaonkar, Ullas Janardhan
Avionics industry is moving towards fly-by wire aircrafts with less reliance on mechanical systems leading to increase in the complexity of in-flight hardware elements. RTCA/DO-254 and EUROCAE ED-80 plays a vital role in the design assurance of airborne electronic hardware. RTCA/ DO-254 and EUROCAE ED-80 are the industry standards for Design Assurance Guidance for Airborne Electronic Hardware. The two different agencies FAA and EU regulate and apply this design assurance guidance to the regulatory law in CFR and EASA CS respectively. This paper discusses the need for DO-254 /ED-80 certification in Aerospace industry, the advantages and benefits to the avionics manufacturers. The paper presents the study made on similarities and differences between DO-254/ED-80.
2016-09-20
Journal Article
2016-01-2030
Jon Zumberge, Michael Boyd, Raul Ordonez
Cost and performance requirements are driving military and commercial systems to become highly integrated, optimized systems which require more sophisticated, highly complex controls. To realize benefits of those complex controls and make confident decisions, the validation of both plant and control models becomes critical. To quickly develop controls for these systems, it is beneficial to develop plant models and determine the uncertainty of those models to predict performance and stability of the control algorithms. A process of model and control algorithm validation for a dc-dc boost converter circuit based on acceptance sampling is presented here. The validation process described in this paper is based on MIL-STD 3022 with emphasis on requirements settings and the testing process. The key contribution of this paper is the process for model and control algorithm validation, specifically a method for decomposing the problem into model and control algorithm validation stages.
2016-09-20
Technical Paper
2016-01-2027
Brett Robbins, Kevin J. Yost, Jon Zumberge
Abstract Detailed machine models are, and will continue to be, a critical component of both the design and validation processes for engineering future aircraft, which will undoubtedly continue to push the boundaries for the demand of electric power. This paper presents a survey of experimental testing procedures for typical synchronous machines that are applied to brushless synchronous machines with rotating rectifiers to characterize their operational impedances. The relevance and limitations of these procedures are discussed, which include steady-state drive stand tests, sudden short-circuit transient (SSC) tests, and standstill frequency response (SSFR) tests. Then, results captured in laboratory of the aforementioned tests are presented.
2016-09-20
Technical Paper
2016-01-2058
Thibaut Billard, Cedric Abadie, Bouazza Taghia
Abstract The present paper reports non-electrically intrusive partial discharge investigations on an aeronautic motor. Relevancy, robustness and repeatability of partial discharge testing procedures, both on insulating materials characterization and on operating aeronautic equipment are essential to ensure reliability of the aircraft systems. The aim of this paper is to be the very first step of defining such procedures and the associated test equipment. To do so, the paper will start by providing an understanding of partial discharge phenomena and will review typical more electrical aircraft architecture. Key characteristics causing partial discharge risk to increase will be highlighted. The impact of harness length, high performance power electronics and voltage level increase on insulation system is demonstrated.
2016-09-20
Technical Paper
2016-01-2052
Virgilio Valdivia-Guerrero, Ray Foley, Stefano Riverso, Parithi Govindaraju, Atiyah Elsheikh, Leonardo Mangeruca, Gilberto Burgio, Alberto Ferrari, Marcel Gottschall, Torsten Blochwitz, Serge Bloch, Danielle Taylor, Declan Hayes-McCoy, Andreas Himmler
Abstract This paper presents an overview of a project called “Modelling and Simulation Tools for Systems Integration on Aircraft (MISSION)”. This is a collaborative project being developed under the European Union Clean Sky 2 Program, a public-private partnership bringing together aeronautics industrial leaders and public research organizations based in Europe. The provision of integrated modeling, simulation, and optimization tools to effectively support all stages of aircraft design remains a critical challenge in the Aerospace industry. In particular the high level of system integration that is characteristic of new aircraft designs is dramatically increasing the complexity of both design and verification. Simultaneously, the multi-physics interactions between structural, electrical, thermal, and hydraulic components have become more significant as the systems become increasingly interconnected.
2016-09-20
Journal Article
2016-01-2051
Andreas Himmler, Lars Stockmann, Dominik Holler
Abstract The application of a communication infrastructure for hybrid test systems is currently a topic in the aerospace industry, as also in other industries. One main reason is flexibility. Future laboratory tests means (LTMs) need to be easier to exchange and reuse than they are today. They may originate from different suppliers and parts of them may need to fulfill special requirements and thus be based on dedicated technologies. The desired exchangeability needs to be achieved although suppliers employ different technologies with regard to specific needs. To achieve interoperability, a standardized transport mechanism between test systems is required. Designing such a mechanism poses a challenge as there are several different types of data that have to be exchanged. Simulation data is a prominent example. It has to be handled differently than control data, for example. No one technique or technology fits perfectly for all types of data.
2016-09-20
Technical Paper
2016-01-2047
K. Suresh, Rajkumar Dhande, Udupi Ananthakrishna Acharya
Abstract Reducing the amount of physical testing is of importance in the aeronautical industry, where each physical test represents a significant cost. Apart from the cost aspect, it may also be difficult or hazardous to carry out physical testing. Specific to the aeronautic industry are also the relatively long development cycles, implying long periods of uncertainty during product development. In any industry a common viewpoint is that of verification, validation, and uncertainty quantification using simulation models are critical activities for a successful development of a product. In Aeronautical application, the design of store's structural equipments needs to be certified in accordance with MIL-T-7743F [1]. This paper focuses on a case study for shock analysis, whereby an attempt has been made to reduce the cost of certification by way of replacing the actual physical testing by a reliable high fidelity FE simulation.
2016-09-20
Technical Paper
2016-01-2044
Jeffrey J. Joyce, Scott Beecher, Laurent Fabre, Ramesh Rajagopalan
Abstract Over the past few decades, advanced methods have been developed for the analysis of digital systems using mathematical reasoning, i.e., formal logic. These methods are supported by sophisticated software tools that can be used to perform analysis far beyond what is practically achievable using “paper and pencil” analysis. In December 2011, RTCA published RTCA DO-178C [1] along with a set of technical supplements including RTCA DO-333 [2] which provides guidance on the use of formal methods towards the certification of airborne software. Such methods have the potential to reduce the cost of verification by using formal analysis instead of conventional test-based methods to produce a portion of the verification evidence required for certification.
2016-09-20
Technical Paper
2016-01-1994
Wei Wu, Yeong-Ren Lin, Louis Chow, Edmund Gyasi, John P. Kizito, Quinn Leland
Abstract For aircraft electromechanical actuator (EMA) cooling applications using forced air produced by axial fans, the main objective in fan design is to generate high static pressure head, high volumetric flow rate, and high efficiency over a wide operating range of rotational speed (1x∼3x) and ambient pressure (0.2∼1 atm). In this paper, a fan design based on a fan diameter of 86 mm, fan depth (thickness) of 25.4 mm, and hub diameter of 48 mm is presented. The blade setting angle and the chord lengths at the leading and trailing edges are varied in their suitable ranges to determine the optimal blade profiles. The fan static pressure head, volumetric flow rate, and flow velocity are calculated at various ambient pressures and rotational speeds. The optimal blade design in terms of maximum total-to-total pressure ratio and efficiency at the design point is obtained via CFD simulation.
2016-09-20
Technical Paper
2016-01-2004
M. Parvez Alam, Dinesh Manoharan
In this paper we discuss about the design and development of an “Autonomous Amphibious Unmanned Aerial Vehicle (AAUAV)” that can fly autonomously to the polluted water areas where human accessibility is formidable to test the water quality. The AAUAV system is an integrated multi-copter with tilt rotor capability to facilitate easy landing, navigation and maneuver on water. A 3D CAD model has been designed and analyzed. A specific propulsion system has been devised and lab tested. A proof of concept model has been made and tested in the field with its instruments to ascertain its technical/ operational feasibility. This system can also be tailored to collect and store the water samples from the polluted sites for further comprehensive research at the laboratory. AAUAV system is the novel solution to the polluted environment through a complete integrated system. This will be an effective alternative for the conventional water sampling techniques.
2016-09-20
Technical Paper
2016-01-2000
Mark Bodie, Thierry Pamphile, Jon Zumberge, Thomas Baudendistel, Michael Boyd
Abstract As technology for both military and civilian aviation systems mature into a new era, techniques to test and evaluate these systems have become of great interest. To achieve a general understanding as well as save time and cost, the use of computer modeling and simulation for component, subsystem or integrated system testing has become a central part of technology development programs. However, the evolving complexity of the systems being modeled leads to a tremendous increase in the complexity of the developed models. To gain confidence in these models there is a need to evaluate the risk in using those models for decision making. Statistical model validation techniques are used to assess the risk of using a given model in decision making exercises. In this paper, we formulate a transient model validation challenge problem for an air cycle machine (ACM) and present a hardware test bench used to generate experimental data relevant to the model.
2016-09-20
Technical Paper
2016-01-2064
Shashank Krishnamurthy, Stephen Savulak, Yang Wang
Abstract The emergence of wide band gap devices has pushed the boundaries of power converter operations and high power density applications. The wide band gap devices in conjunction with silicon on insulator electronic components enable the realization of power converters that can operate at high ambient temperatures that are typically found in aerospace engine environments. This paper describes the design and test of a power electronic inverter that converts a fixed input DC voltage to a variable voltage variable frequency three phase output. The design of the key functional components such as the gate drive, power module, controller and communication will be discussed in this paper. Test results for the inverter at high temperature are also presented.
2016-06-15
Technical Paper
2016-01-1805
Florian Zenger, Clemens Junger, Manfred Kaltenbacher, Stefan Becker
Abstract A low pressure axial fan for benchmarking numerical methods in the field of aerodynamics and aeroacoustics is presented. The generic fan for this benchmark is a typical fan to be used in commercial applications. The design procedure was according to the blade element theory for low solidity fans. A wide range of experimental data is available, including aerodynamic performance of the fan (fan characteristic curve), fluid mechanical quantities on the pressure and suction side from laser Doppler anemometer (LDA) measurements, wall pressure fluctuations in the gap region and sound characteristics on the suction side from sound power and microphone array measurements. The experimental setups are described in detail, as to ease reproducibility of measurement positions. This offers the opportunity of validating aerodynamic and aeroacoustic quantities, obtained from different numerical tools and procedures.
2016-04-05
Journal Article
2016-01-1577
Tateru Fukagawa, Shinnosuke Shimokawa, Eiji Itakura, Hiroyuki Nakatani, Kenichi Kitahama
Abstract The aerodynamic stability of energy-saving, lightweight, and low-drag vehicles is reduced by crosswind disturbances. In particular, crosswinds cause unsteady motion in vehicles with low-drag body shapes due to aerodynamic yaw moment. To verify fluctuations in the unsteady aerodynamic forces of a vehicle, a direct measurement method of these forces in a crosswind test was established using inertial force and tire load data. The former uses an inertia sensor comprised of a gyro, acceleration sensor, and GPS sensor, and the latter uses a wheel force sensor. Noise in the measurement data caused by the natural frequency of the tires was reduced using a spectral subtraction method. It was confirmed that aerodynamic data measured in the crosswind test corresponded to wind tunnel test data. Numerical expressions were defined to model the unsteady aerodynamic forces in a crosswind.
2016-04-05
Technical Paper
2016-01-0463
Juan Sierra, Camilo Cruz, Luis Munoz, Santiago Avila, Elkin Espitia, Jaime Rodriguez
Abstract Brake systems are strongly related with safety of vehicles. Therefore a reliable design of the brake system is critical as vehicles operate in a wide range of environmental conditions, fulfilling different security requirements. Particularly, countries with mountainous geography expose vehicles to aggressive variations in altitude and road grade. These variations affect the performance of the brake system. In order to study how these changes affect the brake system, two approaches were considered. The first approach was centered on the development of an analytical model for the longitudinal dynamics of the vehicle during braking maneuvers. This model was developed at system-level, considering the whole vehicle. This allowed the understanding of the relation between the braking force and the altitude and road grade, for different fixed deceleration requirement scenarios. The second approach was focused on the characterization of the vacuum servo operation.
2015-09-15
Journal Article
2015-01-2385
Richard C. Millar
Abstract Unmanned aviation systems (UAS) acquired for US Navy for military roles are developed in the context of NAVAIR's rigorous and well-established policies, procedures and processes employed in the acquisition and development of manned aircraft. A key process is the preparation and approval of interim flight clearances (IFC) prior to flight test to ensure the aircraft is airworthy and thus safe to operate. Due to the perceived risks of UAS experimental flight test, the use of this process has been mandated for all Navy organizations, including use of commercially available UAS in research projects. This policy has proved to be a challenge, impeding and discouraging the use of UAS in research and experimental projects. Currently, the cost of compliance is unaffordable and IFC preparation and approval time are inconsistent with research cycle time expectations.
2015-09-15
Journal Article
2015-01-2390
Georges Ghazi, Ruxandra Botez, Joseph Messi Achigui
Abstract During aircraft development, mathematical models are elaborated from our knowledge of fundamental physical laws. Those models are used to gain knowledge in order to make decisions in all development stages. Since engine model is one of the most important items in aircraft simulation, the aviation industry has recently developed a high interest on them. With the power capacities development in the last years, numerical simulations have been widely used for predicting engine response. In this paper, a methodology to identify an engine model from flight tests is presented. A Cessna Citation X Level D Flight Simulator designed and manufactured by CAE Inc. was used to sample the engine thrust force data. More than 500 flight tests were made for different flight conditions expressed in Mach numbers (M = 0 to M = 0.9), altitudes (h = 0 ft to h = 50,000 ft) and different throttle positions (idle to maximum).
2015-09-15
Technical Paper
2015-01-2620
Philip Van Baren
Abstract Random vibration control systems produce a PSD plot by averaging FFTs. Modern controllers can set the degrees of freedom (DOF), which is a measure of the amount of averaging to use to estimate the PSD. The PSD is a way to present a random signal-which by nature “bounces” about the mean, at times making high excursions from the mean-in a format that makes it easy to determine the validity of a test. This process takes time as many frames of data are collected in order to generate the PSD estimate and a test can appear to be out of tolerance until the controller has enough data to estimate the PSD with a sufficient level of confidence. Something is awry with a PSD estimate that achieves total in-tolerance immediately after the test begins or immediately after a change in level, and this can hide dangerous over or under test conditions within specific frequency bands, and should be avoided.
2015-09-15
Journal Article
2015-01-2608
Joshua Cemenska, Todd Rudberg, Michael Henscheid
Abstract In many existing AFP cells manual inspection of composite plies accounts for a large percentage of production time. Next generation AFP cells can require an even greater inspection burden. The industry is rapidly developing technologies to reduce inspection time and to replace manual inspection with automated solutions. Electroimpact is delivering a solution that integrates multiple technologies to combat inspection challenges. The approach integrates laser projectors, cameras, and laser profilometers in a comprehensive user interface that greatly reduces the burden on inspectors and decreases overall run time. This paper discusses the implementation of each technology and the user interface that ties the data together and presents it to the inspector.
2015-09-15
Technical Paper
2015-01-2434
Tian Lirong, Mu Ming
Abstract In recent year, with the booming of Chinese economy and domestic civil air transportation market, China's aircraft manufacturers have been trying to develop their own commercial aircraft and changing from the subcontracting-manufacturer to aircraft developer, which turned to be a very hard task. One of the main challenges in front of China's aircraft manufacturers and airborne equipment suppliers is how to apply the airworthiness standards, such as ARP4754A, ARP4761, DO-178B(C) and DO-254, etc, into their engineering practice. Chinese companies are struggling in improving their capabilities to satisfy certification requirements and are making some remarkable progress these years. The paper first introduces the current status of Chinese aviation industry, and then the challenges to China's airborne equipment suppliers are analyzed. Based on these, the customization considerations of airworthiness standards and ARP4754 Practice in Chinese context are discussed.
2015-09-15
Technical Paper
2015-01-2449
Solange Baena, Joseph K-W Lam, Craig Lawson
Abstract This paper focuses on the investigation of the nature, process and effects of ice accretion on different feed pump strainers upstream of the aircraft feeding system. A suitable test rig was designed to circulate Jet A-1 containing water/ice contaminants at cold temperatures through the strainers. Following an extensive literature review, a number of screening tests were performed. These provided a strong base for an exhaustive study of fuel icing in the dynamic environment offered by the test rig. The effects of the rate of fuel cooling on the nature of ice were examined. As expected, it was observed that the yield of ice generated on the mesh screen increased with the water concentration in the fuel. It was also revealed that at higher cooling rates, a crust of snow formed on top of softer ice on the mesh screen.
2015-09-15
Technical Paper
2015-01-2454
Patrick H. Browning, Wade Huebsch
Abstract The design and testing of small unmanned aerial vehicle (sUAV) prototypes can provide numerous difficulties when compared to the same process applied to larger aircraft. In most cases, it is desirable to have a better understanding of the low Reynolds number aerodynamics and stability characteristics prior to completion of the final sUAV design. This paper describes the design, construction, and operational performance of a pneumatic launch apparatus that has been used at West Virginia University (WVU) for the development and early flight testing of transforming sUAV platforms. Although other launch platforms exist that can provide the safe launch of such prototypes, the particular launch apparatus constructed at WVU exhibits unmatched launch efficiency, and is far less expensive to operate per shot than any other launch system available.
2015-09-15
Journal Article
2015-01-2499
Perla Maiolino, Richard A. J. Woolley, Atanas Popov, Svetan Ratchev
Abstract The assembly and manufacture of aerospace structures, in particular legacy products, relies in many cases on the skill, or rather the craftsmanship, of a human operator. Compounded by low volume rates, the implementation of a fully automated production facility may not be cost effective. A more efficient solution may be a mixture of both manual and automated operations but herein lies an issue of human error when stepping through the build from a manual operation to an automated one. Hence the requirement for an advanced automated assembly system to contain functionality for inline structural quality checking. Machine vision, used most extensively in manufacturing, is an obvious choice, but existing solutions tend to be application specific with a closed software development architecture.
2015-09-15
Technical Paper
2015-01-2524
Srikanth Gampa
Abstract Multi core platforms offer high performance at low power and have been deemed as future of size, weight and power constrained applications like avionics safety critical applications. Multi core platforms are widely used in non-real time systems where the average case performance is desired like in consumer electronics, telecom domains. Despite these advantages, multi core platforms (hardware and software) pose significant certification challenges for safety critical applications and hence there has been limited usage in avionics and other safety critical applications. Many multicore platform solutions which can be certified to DO-254 & DO 178B Level A are commercially available. There is a need to evaluate these platforms w.r.t certification requirements before deploying them in the safety critical systems thereby reducing the program risks. This paper discusses the advantages of multi core platforms in terms of performance, power consumption and weight/size.
Viewing 1 to 30 of 2815