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Viewing 91 to 120 of 4781
2015-09-15
Technical Paper
2015-01-2589
Julien Feau, Philippe Chantal, Jayant Sen Gupta
Abstract Modern aircraft, such as A380 or A350 for Airbus, are very well connected in flight to ground stations through wireless communications. For maintenance and operations purpose, the aircraft is programmed to send regularly information such as flight reports based on the BITE messages (Built-In Test Equipment) or standard reports based on the value of physical parameters. Moreover, Airbus is capable of sending requests (called uplinks) to the aircraft to retrieve the value of different parameters in almost real-time. This ability, associated with adequate process, improves significantly the reaction time of the diagnostic and prognostic solutions that Airbus can provide to its customers. Traditionally Health Monitoring is considered useful when the Potential to Functional failure (P-F) interval is greater than one flight cycle.
2015-09-15
Journal Article
2015-01-2440
Robert Moehle, Jason Clauss
Abstract Labor costs rank second only to fuel in expenses for commercial air transports. Labor issues are a growing concern in the airline industry, with an impending worldwide pilot shortage. One solution proposed and requested by some of the industry leaders is to allow a single flight crew member to operate the aircraft. Safety concerns represent the dominant barrier to single-pilot Part 121 operations. The FAA and Congress consistently demonstrate a bias toward conservatism in their regulation of airlines and commercial aircraft. Bureaucrats and the general public fall prey to isolated news stories that highlight pilot error and anchor their viewpoint on further regulating a two-person crew. Yet, in an alarming spate of recent airline accidents, the presence of multiple crewmembers did nothing to prevent, and actually may have contributed to, the crash. Technology is not the problem.
2015-09-15
Journal Article
2015-01-2397
Angelo C. Conner, Luis Rabelo
Abstract In planning, simulation models create microcosms, small universes that operate based on assumed principles. While this can be powerful, the information it can provide is limited by the assumptions made and the designed operation of the model. When performing schedule planning and analysis, modelers are often provided with timelines representing project tasks, their relationships, and estimates related to durations, resource requirements, etc. These timelines can be created with programs such as Microsoft Excel or Microsoft Project. There are several important attributes these timelines have; they represent a nominal flow (meaning they do not represent stochastic processes), and they are not necessarily governed by dates or subjected to a calendar. Attributes such as these become important in project planning since timelines often serve as the basis for creating schedules.
2015-09-15
Journal Article
2015-01-2545
Reza Ahmadi, Oliver Marquardt, Marc Riedlinger, Reinhard Reichel
Abstract Aircraft cabin systems, especially cabin management systems (CMS) have to cope with frequent cabin changes during their lifecycle. This includes not only layout rearrangements and technological upgrades during the service, but also extensive CMS customizations and product variations before aircraft delivery. Therefore it is inevitable for the CMS to be highly changeable and offer an easy and agile change process. Today's CMS solutions face this challenge with configurable system architectures. Although such architectures offer a vast change domain, they usually come with time consuming and error prone change processes. This paper introduces an adaptive avionics software architecture that enables the CMS to cope with cabin changes highly automatically and with minimal human interactions. The adaptation is performed during an on ground organization phase, in which system changes are detected and evaluated by the CMS itself.
2015-09-06
Technical Paper
2015-24-2530
Mohamed El Morsy, Gabriela Achtenova
Abstract A vehicle gearbox serves for torque and speed conversion with help of rotating elements. Therefore the gearbox experiences periodic excitation forces with a fundamental frequency following the rotation frequency. These excitation forces give rise to corresponding periodic response signals, i.e. signals having content at the fundamental (rotational) frequency and its harmonics. Order analysis is an analysis technique which is used to extract these harmonic orders from the response signals. This article intends to use the order tracking analysis for gearbox fault diagnosis under variable speed conditions to compare between healthy and faulty cases by using order extraction. Finally, determine maximum Root Mean Square (RMS) as severity index.
2015-09-06
Journal Article
2015-24-2465
George Bergeles, Jason Li, Lifeng Wang, Foivos Koukouvinis, Manolis Gavaises
Abstract Despite numerous research efforts, there is no reliable and widely accepted tool for the prediction of erosion prone material surfaces due to collapse of cavitation bubbles. In the present paper an Erosion Aggressiveness Index (EAI) is proposed, based on the pressure loads which develop on the material surface and the material yield stress. EAI depends on parameters of the liquid quality and includes the fourth power of the maximum bubble radius and the bubble size number density distribution. Both the newly proposed EAI and the Cavitation Aggressiveness Index (CAI), which has been previously proposed by the authors based on the total derivative of pressure at locations of bubble collapse (DP/Dt>0, Dα/Dt<0), are computed for a cavitating flow orifice, for which experimental and numerical results on material erosion have been published. The predicted surface area prone to cavitation damage, as shown by the CAI and EAI indexes, is correlated with the experiments.
2015-09-01
Journal Article
2015-01-9001
Tarapong Sreenuch, Ian Jennions
For Integrated Vehicle Health Management (IVHM) technology to fully achieve its promise, there is a need for integration architecture to support interoperability between multiple vendors' IVHM components and insertion of new IVHM capabilities. To date there have been very limited studies on different approaches in integrating IVHM components. This paper presents design candidates for plug-and-play (PnP) IVHM architecture. The open standard based designs are derived from desired IVHM data flow characteristics and system configuration requirements. The designs and enabling middleware technologies are qualitatively and empirically evaluated for their adequacy and effectiveness. The qualitative assessment focuses on the implementation and system configuration based on different test scenarios. The empirical performance is measured in terms of latency (in both normal and intermittent network connections) and throughput.
2015-06-15
Technical Paper
2015-01-2097
Timothy A. Shannon, Stephen T. McClain
Abstract Changes in convection coefficient caused by the changes in surface roughness characteristics along an iced NACA 0012 airfoil were investigated in the 61-cm by 61-cm (24 in. by 24 in.) Baylor Subsonic Wind Tunnel using a 91.4-cm (36-in.) long heated aerodynamic test plate and infrared thermometry. A foam insert was constructed and installed on the wind tunnel ceiling to create flow acceleration along the test plate replicating the scaled flow acceleration the along the leading 17.1% (3.6 in.) of a 53.3-cm (21-in.) NACA 0012 airfoil. Two sets of rough surface panels were constructed for the study, and each surface used the same basic random droplet pattern created using the Lagrangian droplet simulator of Tecson and McClain (2013). For the first surface, the roughness pattern was replicated with the same geometry over the plate following a smooth-to-rough transition location noted in historical literature for the case being replicated.
2015-06-15
Technical Paper
2015-01-2102
Guilin Lei, Wei Dong, Jianjun Zhu, Mei Zheng
Abstract The numerical simulation of ice melting process on an iced helicopter rotor blade is presented. The ice melting model uses an enthalpy-porosity formulation, and treats the liquid-solid mushy zone as a porous zone with porosity equal to the liquid fraction. The ice shape on the blade section is obtained by the icing code with a dynamic mesh module. Both of the temperature change and the ice-melting process on the rotor blade section surface are analyzed. The phenomenon of ice melting is analyzed through the change of temperature and liquid fraction on the abrasion/ice interface. The liquid fraction change as with time on the abrasion/ice surface is observed, which describes the ice-melting process well. The numerical results show that the ice melting process can be simulated effectively by the melting model. The de-icing process can be monitored by observing the change of the liquid fraction of the area around the abrasion/ice interface.
2015-06-15
Technical Paper
2015-01-2137
Daniel R. Adriaansen, Paul Prestopnik, George McCabe, Marcia Politovich
Abstract Advancements in numerical weather prediction (NWP) models continue to enhance the quality of in-flight icing forecasts and diagnoses. When diagnosing current in-flight icing conditions, observational datasets are combined with NWP model output to form a more accurate representation of those conditions. Surface observations are heavily relied upon to identify cloud coverage and cloud base height above observing stations. One of the major challenges of using these point-based or otherwise limited observations of cloud properties is extending the influence of the observation to nearby points on the model grid. An alternate solution to the current method for incorporating these point-based observations into the in-flight icing diagnoses was developed. The basis for the new method is rooted in a concept borrowed from signal and image processing known as dithering.
2015-06-15
Technical Paper
2015-01-2093
Maxime Henno
Abstract Advanced sizing of the thermal wing ice protection system (WIPS) requires an improved and a robust manner to simulate the system operation in unsteady phases and particularly in de-icing operations. A two dimensional numerical tool has been developed to enable the simulation of unsteady anti-icing and de-icing operations. For example, the WIPS may be activated with delay after entering into the icing conditions. In this case, ice starts to accrete on the leading edge before the WIPS heats up the skin. Another example is the ground activation of the WIPS for several seconds to check its functionality: low external cooling may cause high thermal constraints that must be estimated with accuracy to avoid adverse effects on the structure. Thermal de-icing WIPS integrated in composite structures intrinsically have unsteady behaviors; the tool enables the computation of the skin temperature evolution with the time.
2015-06-15
Technical Paper
2015-01-2135
Martin Schulz, Michael Sinapius
Abstract A designer of a new mechanical ice protection system for airplanes needs to know how much and in which way he has to deform the surface to break off the ice. The ice adhesion strength is often used as a design value. Several methods have been published to measure the adhesive strength of ice. This paper analyzes the interface stresses created by those methods and discusses the way the adhesion strength is derived. A finite element method tool is used to provide insight into the stress state for different load cases. The implication of these illustrations is that equations which use only ultimate force and total interfacial area to calculate adhesion strength miss local stress concentrations and crack nucleation. Hence, the derived adhesion strength may not be comparable within different testing methods, because each testing procedure neglects different parameters like specimen size, substrate thickness and stiffness.
2015-06-15
Technical Paper
2015-01-2120
Yong Han Yeong, Eric Loth, Jack Sokhey, Alexis Lambourne
Researchers have recently focused on superhydrophobic coatings as an ice-mitigation tool. These surfaces have a high degree of water-repellency and were shown in previous low-speed droplet studies to reduce surface ice adhesion strength. However, there is little research regarding testing in aerospace icing conditions, i.e. high-speed super-cooled droplet impact (> 50 m/s) on a freezing substrate and air temperature. A detailed set of experiments were conducted in an icing wind tunnel to measure the ice adhesion strength of various superhydrophobic coatings by subjecting the surfaces to a super-cooled icing cloud consisting of 20 μm droplets and at a constant LWC of 0.4 g/m3. Test conditions include air speeds of 50 m/s and 70 m/s and in glaze (−5°C) and rime ice regimes (−15°C). The accreted ice was then removed by pressurized nitrogen in a mode 1 (tensile) adhesion test.
2015-06-15
Technical Paper
2015-01-2092
David M. Orchard, Catherine Clark, Myron Oleskiw
Abstract Simulations of supercooled large droplet (SLD) icing environments within the NRC's Altitude Icing Wind Tunnel (AIWT) have been performed in which broad band mass distribution spectra are achieved that include a distinct pattern of liquid water content (LWC) over a range of droplet sizes (i.e., bi-modal distribution). The mass distribution is achieved through modification of the existing spray system of the AIWT to allow two spray profiles with differing LWC and median volumetric diameter (MVD) to be simultaneously injected into the flow. Results of spray profile distributions measured in the test section have demonstrated that freezing drizzle conditions, where MVD is either less than or greater than 40 μm, can be achieved.
2015-06-15
Technical Paper
2015-01-2078
Alric Rothmayer, Hui Hu
Abstract A strong air/water interaction theory is used to develop a fast simplified model for the trapping of water in a film that flows over sub-grid surface roughness. The sub-grid model is used to compute correction factors that can alter mass transport within the film. The sub-grid model is integrated into a covariant film mass transport model of film flow past three-dimensional surfaces in a form that is suitable for use in aircraft icing codes. Sample calculations are presented to illustrate the application of the model.
2015-06-15
Technical Paper
2015-01-2158
Tatsuma Hyugaji, Shigeo Kimura, Haruka Endo, Mitsugu Hasegawa, Hirotaka Sakaue, Katsuaki Morita, Yoichi Yamagishi, Nadine Rehfeld, Benoit Berton, Francesc Diaz, Tarou Tanaka
Coating has been recently considered as having good potential for use in preventing in-cloud icing on the leading edge of the lifting surfaces of an aircraft in cold climates. In terms of wettability, a coat may exhibit hydrophobicity or hydrophilicity depending on its specific properties. The same applies to the ice adhesion strength, which may be either high or low. It is thus necessary to determine which type of anti-icing or de-icing coat would be appropriate for a particular application in order to fully utilize its specific properties. Notwithstanding, a coat is incapable of preventing ice accretion by itself, and a perfect icephobic coat is yet to be developed. Coating is also sometimes applied to the surfaces of electrical heaters and load-applying machines to enable them to function more effectively and use less energy. The coating used for an electric heater, for instance, should be hydrophobic because of the need for rapid removal of molten water from the surface.
2015-06-15
Technical Paper
2015-01-2159
Philipp Grimmer, Swarupini Ganesan, Michael Haupt, Jakob Barz, Christian Oehr, Thomas Hirth
Abstract As known de-icing methods use a high amount of energy or environmentally harmful chemicals, research has focused lately on passive de-icing by functional surfaces with an improved removal of ice (de-icing) or a reduced formation of it (anti-icing). Inspired by the Lotus plant leaf, a “superhydrophobic” surface can be produced by the combination of a hierarchical micro/nanoscale roughness and a hydrophobic surface coating. By a hot stamping process we have generated differently shaped microstructures (cylinders, ellipses) on polyurethane (PU) films which were afterwards coated by a plasma enhanced chemical vapor deposition (PECVD) process with thin, hydrophobic fluorocarbon films. This combination of methods could be a process for the production of large area functionalized films. PU films are suitable for outdoor use, because they are resistant against erosion and UV radiation. The films can be glued to different geometries and can easily be exchanged if damaged.
2015-06-15
Technical Paper
2015-01-2160
Alidad Amirfazli
Abstract The surfaces that shed drops helps with mitigation of icing. Shedding of drop depends on surface hydrophobicity, which becomes affected when exposed to water and/or UV. The hydrophobicity degradation of six (Spray SHS, Etched Al SHS, Hydrobead, Neverwet, Waterbeader, and WX2100) different super-hydrophobic surfaces (SHS), exposed to water or UV, were studied from the drop shedding perspective. Two methods were adopted for the hydrophobicity analysis. Among them, one is to study the contact angles (CA) and contact angle hysteresis (CAH) change at static state (i.e., no airflow) compared to the untreated surface. The other one is to analyze the change in critical air velocity (Uc) for a given drop exposed to airflow, on water/UV treated surfaces at room temperature (22 °C) and icing conditions (−1 and −7 °C).
2015-06-15
Technical Paper
2015-01-2157
Mengyao Leng, Shinan Chang, Yuanyuan Zhao
Abstract Aircraft icing causes a great threaten to flight safety. With the development of anti-icing or de-icing systems for aircraft, some attention has been paid on coating strategies for an efficient way to prevent water remaining on the surface. By application of hydrophobic or super-hydrophobic coatings, characterized by low surface adhesion, shedding of liquid from the surface can be enhanced. The motivation behind this work is to identify the way that wettability affects the motion of runback water, and establish an empirical formula of critical departure diameter. The surface property is characterized by the equilibrium contact angle and the hysteresis angle. The relationship between the air speed and the droplet shedding diameter is studied, corresponding to different surfaces.
2015-06-15
Technical Paper
2015-01-2076
Caroline Laforte, Neal Wesley, Marc Mario Tremblay
Abstract This study presents a new method to evaluate and compare the anti-icing performance, i.e., the ability to delay the reformation of ice, of runways and taxiways deicing/anti-icing fluids (RDF) under icing precipitation, based on the skid resistance values, obtained with the Portable Skid Resistance Tester (PSRT). In summary, the test consists of applying, on a standardized concrete pavement sample, a given quantity of de-icing fluid. Following this application, the concrete sample is submitted to low freezing drizzle intensities, in a cold chamber at −5.0 ± 0.3°C. The skid resistance of concrete is measured at 5 minute intervals, until the concrete becomes completely iced. The anti-icing performance of 5 different fluids, both experimental and commercial, was assessed in comparison with a reference solution of 50% w/w K-formate. The anti-icing performance is analyzed based on two parameters: the duration (Icing Protection Time, IPT) and the effectiveness of this protection.
2015-06-15
Technical Paper
2015-01-2149
Caroline Laforte, Caroline Blackburn, Jean Perron
Abstract This paper depicts icephobic coating performances of 274 different coatings, including 11 grease-type coatings, which were tested over the past 10 years in various research projects at the Anti-Icing Materials International Laboratory (AMIL). Icephobic performance is evaluated using two comparative test methods. The first method, the ice Centrifuge Adhesion Test (CAT), measures the force required to separate the accreted ice from the coating (e.g. adhesive failure). The test involves simultaneously icing, under supercooled precipitation, the extremity of bare reference and freshly coated aluminum samples. The ice adhesion shear stress is calculated from the ice detachment rotation speed. The results are reported as Adhesion Reduction Factor (ARF), which is the ice adhesion stress on the bare aluminum reference samples divided by the ice adhesion stress on the coated samples.
2015-04-14
Technical Paper
2015-01-0926
Tianyun Li, Min Xu, David Hung, Shengqi Wu, Siqi Cheng
Abstract Comparing with port-fuel-injection (PFI) engine, the fuel sprays in spark-ignition direct-injection (SIDI) engines play more important roles since they significantly influence the combustion stability, engine efficiency as well as emission formations. In order to design higher efficiency and cleaner engines, further research is needed to understand and optimize the fuel spray atomization and vaporization. This paper investigates the atomization and evaporation of n-pentane, gasoline and surrogate fuels sprays under realistic SIDI engine conditions. An optical diagnostic technique combining high-speed Mie scattering and Schlieren imaging has been applied to study the characteristics of liquid and vapor phases inside a constant volume chamber under various operating conditions. The effects of ambient temperature, fuel temperature, and fuel type on spray atomization and vaporization are analyzed by quantitative comparisons of spray characteristics.
2015-04-14
Technical Paper
2015-01-1249
Jinli Wang, Fuyuan Yang, Minggao Ouyang
Abstract There is increasing demand for engine diagnostic and control with in-cylinder pressure signal. However, the application of cylinder pressure sensors are restricted by the high cost of the sensor. Another possible way for engine combustion state estimation is by processing of instantaneous crankshaft speed signal, but it is limited by the precision and complexity of the algorithm. It could be a solution by processing one cylinder pressure signal in combination with a crankshaft speed signal. The indicated torque could be estimated through engine speed processing and also from the measure cylinder pressure for the reference cylinder. Measurement results from experiments show that the indicated torque error traces of different cylinder are similar in shape. According to this assumption, the reference cylinder with cylinder pressure signal available can serve as both a parameter calibration information source and an error reduction measure.
2015-04-14
Technical Paper
2015-01-0881
Sunyu Tong, Haimiao Li, Zhaohui Yang, Jun Deng, Zongjie Hu, Liguang Li
Abstract An ion current sensor is employed in a 4 cylinder production SI engine for combustion diagnosis during combustion process, knock, and low speed pre-ignition (LSPI) detection. The results show that the ion current peak value and ion current peak phase have strong correlation with the cylinder pressure and pressure peak phase respectively. The COV of ion current integral value is greater than the COV of IMEP at the same operating condition. Results show that the ion current signal is sensitive to different lambdas. Using ion current signal, the knock in any given cylinder can be detected. Importantly, the ion sensor successfully detected the low speed pre-ignition (LSPI) about more than 20 °CA before spark ignition.
2015-04-14
Journal Article
2015-01-0206
Jihas Khan
Abstract Security access feature based on seed-key mechanism is widely used in automotive electronics, mainly for flashing ECU software, writing or reading specific parameter values and running diagnostic routines. There exist a number of techniques to decode the algorithm for key generation from a specific seed. Such techniques can put vehicle network at great risks due to an intruder flashing unauthorized version of ECU software, or changing internal parameters of ECU, or changing a VIN number. A lot more similar malicious attacks can be done by getting control over the ECUs. Attackers can exploit this vulnerability to alter the performance from the stock and affect the safety of the passengers. A novel and fool proof algorithm to protect the vehicle and ECU from such malicious attacks is explained in this paper. An advanced encryption technique is developed and tested in ECU to replace the current seed-key mechanisms for ECU security guarantying a secure operation of the vehicle.
2015-04-14
Technical Paper
2015-01-0486
Jamshid Mohammadi, Mehdi Modares
Abstract Performance data offers a powerful tool for system condition assessment and health monitoring. In most applications, a host of various types of sensors is employed and data on key parameters (describing the system performance) is compiled for further analysis and evaluation. In ensuring the adequacy of the data acquisition process, two important questions arise: (1) is the complied data robust and reasonable in representing the system parameters; and (2) is the duration of data acquisition adequate to capture a favorable percentage (say for example 90%) of the critical values of a given system parameter? The issue related to the robustness and reasonableness of data can be addressed through known values for key parameters of the system. This is the information that is not often available.
2015-04-14
Technical Paper
2015-01-0487
Lev Klyatis
Abstract This paper will discuss the problem with successful predicting of product performance (reliability, quality, durability, safety, recalls, profit, life cycle cost, and other interconnected technical and economic components of performance). The best component for analysing the performance situation during service life, including predicting, is recalls, because, first, recall accumulates the safety, reliability, durability, quality, profit, and total economic situation. And second, there is open official and objective information about the number of recalls from Government (National Highway Trafic Safety Administration and others), as well as companies-producers. Therefore, for analyzing the situation with the product performance, including predicting, this paper considers the situation with recalls.
2015-04-14
Technical Paper
2015-01-0494
Sulki Seong, Wangoo Kim, Daesung Bae, Seungpyo Lee, Younggeol Cho, Kyeongdeok Yang
Abstract A rotating bearing must have an excellent durability life. Various studies have been conducted for a long time to predict the bearing durability life. However, the bearing durability life has been predicted by an analytic formula in terms of the raceway and ball. A finite element structural analysis has been carried out for a flange, commonly with an assumption of a static load. So it is difficult to consider the dynamic effects (Centrifugal force, Gyroscope effect) of the bearing, which is very important due to its high speed operation. In order to predict the accurate bearing durability life, the dynamic effects must be considered. This paper proposes a method for bearing durability life prediction, considering dynamic effects. Contact between the raceway and ball is one of the important factors to take into account for the dynamic effects of the bearing.
2015-04-14
Journal Article
2015-01-0441
Takashi Takiguchi, Yusuke Yano, Yasuhiro Takii, Nobuyuki Ohta
Abstract With demands for enhanced environmental performance such as fuel economy, the tendency has been to reduce the amount of wind introduced to the engine room to reduce drag. Meanwhile, exhaust gas temperatures are increasing in order to reduce emissions concentrations. As a result, the temperature environments for parts inside the engine room and underfloor parts are becoming harsher, and accurately understanding the temperature environments of parts is crucial in determining Engine room component layout during vehicle development and applying effective thermal countermeasures. Computational fluid dynamics (CFD) are effective for understanding complex phenomena such as heat generation and cooling. However, this paper reports the development of a method for accurately calculating the vehicle temperature distribution through identification from test results.
2015-04-14
Technical Paper
2015-01-0439
Daniel B. Kosinski
Abstract The current reliability growth planning model used by the US Army, the Planning Model for Projection Methodology (PM2), is insufficient for the needs of the Army. This paper will detail the limitations of PM2 that cause Army programs to develop reliability growth plans that incorporate unrealistic assumptions and often demand that infeasible levels of reliability be achieved. In addition to this, another reliability growth planning model being developed to address some of these limitations, the Bayesian Continuous Planning Model (BCPM), will be discussed along with its own limitations. This paper will also cover a third reliability growth planning model that is being developed which incorporates the advantageous features of PM2 and BCPM but replaces the unrealistic assumptions with more realistic and customizable ones.
Viewing 91 to 120 of 4781