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2015-06-15
Technical Paper
2015-01-2109
Rodrigo Domingos, Daniel Silva
This paper outlines a three-dimensional computer model named AIPAC suitable for bleed-air ice protection system parametric studies in support of system design and optimization. This 3D simulation code was derived from HASPAC, which is a 2D anti-icing model developed at Wichita State University in 2010. AIPAC is based on the Finite Volumes Method and, similarly to HASPAC, combines a commercial Navier-Stokes flow solver with a Messinger model based thermodynamic analysis that applies internal and external flows heat transfer coefficients, pressure distribution, wall shear stress, etc, to compute wing leading edge skin temperatures, 3D runback flow distribution, and the location, extent and rate of icing. In addition, AIPAC was built using a transient formulation and with the capability of extruding a 3D surface mesh into a volumetric domain, so that “single-shot” ice shapes can be predicted (a more accurate multiple-step ice growth methodology is currently being developed).
2015-06-15
Technical Paper
2015-01-2083
Daniel Silva, Thais Bortholin, J Allan Lyrio, Luis Santos
An important issue regarding landing performance is the reference speed which determines the approved fields lengths in which a landing can take place. The critical scenario is the accumulation of ice during the holding phase followed by descent, approach and landing. The effect of icing in the landing configuration, with the high-lift devices deployed, is relevant and should be anticipated during the early design phases by simulation. Due to the complex behaviour of the flowfield, 3D CFD methods has been used but that leads to a high computational cost which might be too intensive for the preliminary design phases . The purpose of this paper is to describe a lower cost procedure combining CFD and Quasi-3D modified Weissinger´s Method [3] which provides an accurate assessment of these effects to 5% margin in ∆CL , confirmed by wind tunnel testing.
2015-06-15
Technical Paper
2015-01-2100
Yongsheng Lian, Yisen Guo
This paper investigated impingement of supercooled large droplets onto smooth solid surfaces to understand the mechanism of splashing and secondary droplets formation using a novel moment of fluid (MOF) method. Previous studies have established a splashing threshold, but the effect of ambient gas in liquid droplet splashing is not fully understood. Our numerical results of water droplet splashing with relatively low velocity were consistent with experimental results: splashing occurs at high pressure but not at low pressure. Our simulation revealed that a thin film was formed after the droplet contacted the solid surface. The thin film moved at a lower speed at the contact with the solid due to viscous effect while the film moved at a higher speed away from the solid. As a result, air was trapped under the film, making the film floating on the air. When the pressure was high, the air density was high hence the aerodynamic forces by the air on the thin film.
2015-06-15
Technical Paper
2015-01-2101
Hai Li, Ilia Roisman, Cameron Tropea
Airframe icing is a topic of vital importance in aviation industry because it is mainly concerned with the safe and efficient operation of aircraft under all weather conditions. Over the last 15 years the role of supercooled large droplets (SLD) in aircraft icing has received increased attention. Recent meteorological investigations on icing weather have highlighted the existence of icing cloud characteristics beyond the actual certification envelope defined by the 14 CFR Part 25 Appendix C: Atmospheric Icing Conditions for Aircraft Certification, which accounts for an icing envelope characterized by water droplet diameters up to 50 μm. The mechanisms of impact and solidification of SLD are still not completely understood. The main subject of the present study is an investigation of impact of a supercooled drop onto a superhydrophobic substrate. Drop impact, spreading and rebound are observed using a high-speed video system.
2015-06-15
Technical Paper
2015-01-2122
Cameron Butler, Eric Loth
INTRODUCTION To support a collaborative research project aimed at studying icing on large-scale, swept wings, unsteady simulations were performed on test articles with and without icing in NASA Glenn’s Icing Research Tunnel (IRT). The models being tested are all swept hybrid models designed to have the same leading-edge geometry as a 65% scaled version of the Common Research Model (CRM). Three models were designed as hybrid airfoils where the leading edge geometry and flow field matched that of the CRM, but the rest of the airfoil was reduced substantially in length to accommodate the tunnel cross-section. This hybrid design allows for the largest leading-edge which avoids complex issues associated with geometric scaling in icing conditions. To investigate the effect of sweep along the wing, three different test models are investigated to represent different spanwise locations along the CRM, from inboard, mid-span and outboard.
2015-06-15
Technical Paper
2015-01-2117
Miki Shimura
It is well known that SLD icing is very dangerous because it is more unpredictable than general icing caused by smaller droplets. In SLD conditions, extraordinary phenomenon occurs. For example, SLD largely deforms. Vargas et al. (2010) performed the experiments about the droplet deformation. In their experiments, it was confirmed that the droplet height increases and the droplet width decreases, as the droplets approach the leading edge of an airfoil Therefore, the assumption that a droplet behaves as a sphere is no longer valid. To predict the deformation and the breakup of a droplet, several mathematical models have been proposed. For example, Ibrahim et al. (1993) proposed a model for the droplet deformation and breakup (DDB) model. However, the DDB model has not found wide acceptance. Other models exist, in which the deformation is described with the change of drag coefficient.
2015-06-15
Technical Paper
2015-01-2157
Mengyao Leng, Shinan Chang, Yuanyuan Zhao
Aircraft icing causes a great threaten to flight safety. With the development of anti/de-icing systems for aeronautics, some attention is paid on coating strategies for reducing the total amount of water present on the surface. By application of hydrophobic or super-hydrophobic coatings, characterized by low surface wettability, 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. In order to contain the effect of surface wettability, it is necessary to obtain an accurate model for calculating dynamic contact angle (DCA). Instead of average static contact angle or empirical equation, the formula used in this work is derived theoretically, as a function of the capillary number, advancing and receding contact angle, and the roughness of the solid surface.
2015-06-15
Technical Paper
2015-01-2151
Reinhard F.A. Puffing, Wolfgang Hassler, Andreas Tramposch, Marian Peciar
For studying ice accretion processes experimentally and establishing a valuable validation basis for ice accretion simulation models it is desirable to document experimentally generated ice shapes as accurately as possible. The generated set of data then forms the basis for aerodynamic studies, the improvement of icing test facilities, the development of design criteria, the development of ice accretion simulation tools as well as a number of further applications. In the past, various ice shape documentation methods have been established. These include photography, cross-sectional tracing, molding and casting as well as 3D-scanning. Photography is the easiest and fastest documentation method but provides little quantitative information on the ice accretion process itself. Additional quantitative information can be obtained by using multiple cameras or calibrated camera positions which, however, implicates significant additional time and cost efforts.
2015-06-15
Technical Paper
2015-01-2142
Colin Hatch, Roger Gent, Richard Moser
Summary Initial results from a hybrid electro-thermal electro-mechanical simulation (HETEMS) analysis tool are presented and compared to data measured during a dedicated icing trial. Temperatures and ice shed prediction data are compared with the data measured on a full size wing tested in the CIRA Icing Wind Tunnel (IWT) Additional Test Section (ATS). Background The demand for low power ice protection systems was one of the components of the EU Clean Sky initiative [1]. Under Clean Sky a research programme HETEMS looked at the development of a tool to analyse electro-thermal (ET) and electro-mechanical (EM) ice protection systems (IPS). The tool was intended to analyse independent ET and EM systems or a hybrid system using both technologies combined. The aims and scope of the tool are presented in [2]. The HETEMS software was developed around open source tools for the aerodynamic analysis [3] and mechanical failure analysis [4] in conjunction with in-house software.
2015-06-15
Technical Paper
2015-01-2162
Krzysztof Szilder, Edward Lozowski
Atmospheric icing resulting from freezing rain, freezing drizzle and freezing cloud droplets occurs when airborne supercooled water drops freeze on objects they encounter. This process is especially hazardous to aircraft, when the build-up of ice changes the stability and control characteristics of the aerodynamic surfaces. Ice can also be shed with disastrous consequences, if it is ingested into engines, strikes the aircraft or leads to unbalanced aerodynamics forces. Ice accretion is a complex phenomenon involving 3-D multi-phase flow, heat transfer, and gravitational, viscous, surface tension and shear forces. An ability to predict how ice accretes on engineering structures is essential to the prediction of its associated aerodynamic penalties. We have developed an original icing modelling capability, called the “morphogenetic” approach, based on a discrete formulation and emulation of ice formation physics.
2015-06-15
Technical Paper
2015-01-2110
Jozef Brzeczek, Janusz Pietruszka, Robert J. Flemming, Ben C. Bernstein
The PZL M28 05 airplane is an unpressurized twin-engine high-wing strut-braced monoplane of all-metal structure, with twin vertical tails and a tricycle non-retractable landing gear. It is certified to European Aviation Safety Agency (EASA) and Federal Aviation Administration (FAA) requirements. Airplane is certified to flight into known icing conditions in accordance with 14 CFR 23.1419 requirements, including flight in the icing conditions of Appendix C of 14 CFR 25. The PZL M28 05 airplane has characteristics that include short takeoff and landing (STOL) capability, high useful load, mission versatility and easy access through the rear cargo door. Depending on the equipment installed, the airplane can be operated with up to 19 passengers, as a cargo transport, in a mixed configuration, or in patrol version. The M28 is certificated in the Part 23 commuter category. The M28 05 maximum take off gross weight is 7500 kg (16534 lb) and the maximum operational airspeed (VMO) is 192 KIAS.
2015-06-15
Technical Paper
2015-01-2135
Martin Schulz, Michael Sinapius
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 design value. To measure the adhesive strength several methods have been published. This paper presents a review about those methods and discusses the way the adhesion strength is derived. Finite Element Method is used to give a good insight into the stress state at failure 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 the local stress state at the crack tip and the complex process of crack growing. Hence the derived adhesion strength may not be comparable with others, because they depend in fact on neglected parameters like specimen size, substrate thickness and stiffness.
2015-06-15
Technical Paper
2015-01-2201
Paul B. Murray, Jason T. Kunio, Leif Christensen, Flemming S. Larsen
Acoustic material testing is becoming increasingly relevant to engineers, designers and manufacturers from a broad range of industries. This paper presents comparisons between material absorption measurements made using the traditional approaches of the reverberation room method and the fixed impedance tube using a sample holder, and compares the results with those obtained using a new portable flanged impedance tube method. The portable tube allows fast non-destructive in-situ material measurements. They therefore include the impact of the installed lay-up (e.g. effects of facing sheets, curvature, material compression, bagging, etc). Comparison between the varying measurement techniques shows that the portable meter data are more repeatable than both the reverberation room and sample holder procedures. The repeatability of the reverberation room absorption results is subject to variations in panel edge diffraction, non-diffuse field conditions, and source/ receiver repeatability.
2015-06-15
Technical Paper
2015-01-2234
Giancarlo Chiatti, Ornella Chiavola, Silvia Conforto, Manfredi Amalfi
Besides pollutant emissions, fuel consumption and performance, vehicle NVH constitutes a further object during engine development and optimization. In recent years, research activity for diesel engine noise reduction has been devoted to investigate aerodynamic noise due to intake and exhaust systems and surface radiated noise. Most of the attention has been devoted to the identification and analysis of noise sources in order to evaluate the individual contribution (injection, combustion, piston slap, turbocharger, oil pump, valves) to the overall noise with the aim of selecting appropriate control strategies. Several studies have been devoted to analyze combustion process that has a direct influence on engine noise emission; the influence of injection strategies on the combustion noise has been evaluated and approaches able to separate engine combustion and mechanical noise have been presented.
2015-06-15
Technical Paper
2015-01-2235
Arnaud Caillet, Denis Blanchet
The need in the automotive industry to understand the physical behavior of trims used in a vehicle is high. The PEM (poro-elastic method) was developed to permit an explicit representation of the trims in the FEM full vehicle models and to give tools to diagnose the effect of the trims and test design changes (porous material property, geometry…). During the last decade, the evolution on software and hardware sides have allowed to create models with a highly detailed trim description (Porous material using the Biot parameters, plastic trims...). These models can provide a good correlation up to 400Hz against the measurements compared to the classical NSM methodology which shows limitations.
2015-06-15
Technical Paper
2015-01-2236
Parimal Tathavadekar, Ricardo O. de Alba Alvarez, Michael Sanderson, Rabah Hadjit
Finite element analysis (FEA) is commonly used in the automotive industry to predict low frequency NVH behavior (<150 Hz) of structures. Also, statistical energy analysis (SEA) framework is used to predict high frequency (>400 Hz) noise transmission from the source space to the receiver space. A comprehensive approach addressing the entire spectrum (>20 Hz) by taking into account structure-borne and air-borne paths is not commonplace. In the works leading up to this paper a hybrid methodology was employed to predict structure-borne and air-borne transfer functions up to 1000 Hz by combining FEA and SEA. The dash panel was represented by FE structural subsystems and the noise control treatments (NCTs) and the pass-throughs were characterized via testing to limit uncertainty in modeling. The rest of the structure and the fluid spaces were characterized as SEA subsystems.
2015-06-15
Technical Paper
2015-01-2242
Ling Zheng, Zhanpeng Fang
The design optimization of interior noise in vehicle is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is predicted by using finite element method. The minimization of sound pressure inside cabins depends on body structure and the thickness for each panel. The panel participation analysis is carried out to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is proposed and utilized to optimize the vibro-acoustic properties of body structure instead of complex structural-acoustic coupling finite element model. The accuracy of the proposed RSM is evaluated and discussed. Structural-acoustic problem is approximated by a series of quadratic polynomial using RSM. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.
2015-06-15
Technical Paper
2015-01-2241
Hiromichi Tsuji
In the product development phase, the noise transfer functions (NTF) from the wheel or the tire contact patch to the passenger ear location are evaluated by the impact hammer or the ground excitation. However, no reduction of the road noise spectrum under the driving condition is occurred even if the level of the NTF peaks acquired by these methods reduces by the countermeasures on the structure. This is because the vehicle NTF of the road noise performance cannot be evaluated with the existed test equipment, such as the impact on the wheel or the 3 or 6 directional electromagnetic shaker on the ground. The cause of the issue is difficulty to excite the same structural modes coupled with acoustic modes as the one under the driving condition. Road Noise is generated by the change of random displacement input inside tire contact patch.
2015-06-15
Technical Paper
2015-01-2244
Ulhas Dilipraj Mohite, Niket Bhatia, Prashant Bhavsar
Noise radiated from motorcycle engine is gaining significance not only to meet regulations but also to fulfil customer demands of quiet products. In IC engines, combustion pressure is one of the major excitations which is transmitted through powertrain to the casings and radiate noise. Early identification and correction of the casing critical areas contributing to noise will lead to substantial cost and development time reduction. In this paper the approach to predict engine noise under combustion forces is presented. This Methodology is divided into three stages: 1. Multi body dynamic (MBD) Simulation to determine excitation forces 2. Vibration analysis of engine under combustion load 3. Acoustic analysis of engine to predict Sound Pressure Level (SPL). Important parts of motorcycle engine with single cylinder are considered as flexible bodies for MBD simulation.
2015-06-15
Technical Paper
2015-01-2238
Marina Roche
Emissions and fuel consumption reduction for the year 2020 have lead to development of complex powertrain solutions, namely powersplit, electric and hybrid. The development of new concepts presents challenges for the integration in the vehicle, involving NVH among others. Electric energy flow to AC motors is controlled indeed by inverters that transform the energy from DC to AC working at frequencies around 10 kHz. Furthermore, the control of the energy flow can abruptly switch the operating strategy, inducing phenomena that are not present in combustion vehicles. Continuous wavelet transform is a relatively recent mathematical tool which allows signal decomposition into both time and frequency by convolution. On the contrary to windowed Fourier transform, it presents a minimized time support suited to the duration of the phenomena at each frequency. This characteristic makes it well-suited to for identifying transient information in non-stationary signals.
2015-06-15
Technical Paper
2015-01-2240
Gong Cheng, David W. Herrin
The theory of patch (or panel) contribution analysis is first reviewed and then applied to a motorcycle engine on a test stand. The approach is used to predict the sound pressure in the far field and the contribution from different engine components to the sound pressure at a point. First, the engine is divided into a number of patches. The transfer function between the sound pressure in the field and the volume velocity of a patch is determined by taking advantage of vibro-acoustic reciprocity. An inexpensive monopole source is placed at the receiver point and the sound pressure is measured at the center of each patch. With the engine idling, a P-U probe was used to measure particle velocity and sound intensity simultaneously on each patch. The contribution from each patch to the target point is the multiplication of the transfer function and the volume velocity, which can be calculated from particle velocity or sound intensity. There were two target points considered.
2015-06-15
Technical Paper
2015-01-2237
Nickolas Vlahopoulos, Sergey Medyanik
Structural-Acoustic Joints for Incompatible Models in the Energy Finite Element Analysis Sergey Medyanik, Michigan Engineering Services, LLC Nickolas Vlahopoulos, University of Michigan In the EFEA method, the governing differential equations are formulated for an energy variable that has been spatially averaged over a wavelength and time averaged over a period. Differential equations are derived for all wave bearing domains within a system. Each differential equation represents a power balance over a control volume. The corresponding fundamental solutions vary exponentially with space, thus requiring only a small number of elements to capture numerically the smooth spatial variation. Joint matrices are required between the finite elements at locations where discontinuities in the primary EFEA variables exist.
2015-06-15
Technical Paper
2015-01-2239
Nicholas N. Kim, Seungkyu Lee, J Stuart Bolton, Jon Alexander, Taewook Yoo, Sean Hollands
Because of the increasing concern with vehicle weight, there is an interest in lightweight materials that can serve several functions at once. Here we consider the vibration damping performance provided by an “acoustical” material (i.e., a fibrous layer that would normally be used for airborne noise control). First, earlier work related to the damping potential of fibrous, noise control materials is reviewed, and the primary damping mechanism is identified. It has been previously established that the vibration of panel structures creates a non-propagating nearfield in the region close to the panel. In that region, there is an oscillatory, incompressible fluid flow parallel to the panel whose strength decays exponentially with distance from the panel. When a fibrous medium is placed close to the panel in the region where the oscillatory nearfield motion is significant, energy is dissipated by the viscous interaction of the flow and the fibers, and hence the panel vibration is damped.
2015-06-15
Technical Paper
2015-01-2304
Hiroko Tada
In order to achieve a good balance between quietness in the vehicle interior cavity and lighter vehicle weight, it is necessary to study and optimize the specifications of the sound-proof packages. And, this optimization study is advisably done in the early stage of the vehicle development. For challenging to this antinomic, the process for improving automotive interior quietness (as related to air-borne noise above 400 Hz, considered the high-frequency range), with setting the marketability targets, the vehicle body acoustical performances and the parts specifications, was established. With conventional methods, it is challenging to disseminate the relationship between the overall vehicle performance and the performance of individual parts directly. Moreover, without new methods, it is also challenging to propose detailed specifications for the optimal sound-proof packages directly.
2015-06-15
Technical Paper
2015-01-2332
Jan Deleener, Akira Sekitou, Masanori OHTA
Shift feeling is an important comfort attribute for manual transmission driven vehicles. For front-wheel-drive vehicles, there are 3 main parts of interest: the gearbox, the shifter and the shift cable. Often only a test based evaluation process on the actual assembly is available in the later stages of development. In order to frontload the shift feeling evaluation a virtual simulation process is required. For the shift lever and the gearbox there are well established models available. With 3D multibody models or even 2D planar models the effect of kinematics and compliances like connection stiffness and friction are already studied today. However, the modelling of the transmission cable, connecting the gearbox and the shifter remains a challenge to accurately represent the physical feel. By experience it was known that the 3D positioning and curvature of the cable affected the friction force and therefore the shift feeling.
2015-06-15
Technical Paper
2015-01-2333
Brandon Sobecki, Patricia davies, J Stuart Bolton, Frank Eberhardt
Component sound quality is an important factor in the design of competitive diesel engines. One component noise source that causes complaints is the gear rattle that originates in the front-of-engine gear train which drives the fuel pump and other accessories. The rattle is caused by repeated tooth impacts resulting from fluctuations in differential torsional acceleration of the driving gears. These impacts generate a broadband, impulsive noise that is often perceived as annoying. In most previous work, the overall sound quality of diesel engines has been considered without specifically focusing on predicting the perception of gear rattle. Gear rattle level has been quantified based on angular acceleration measurements, but those measurements can be difficult to perform. Here, the emphasis was on developing a metric based on subjective testing of the perception of gear rattle.
2015-06-15
Technical Paper
2015-01-2334
David Bogema, Gary Newton, Mark Stickler, Chris Hocking, Frank Syred
Realistically experiencing the sound and vibration data through actually listening to and feeling the data in a full-vehicle NVH simulator remarkably aids the understanding of the NVH phenomena and speeds up the decision-making process. In the case of idle vibration, the sound and vibration of the idle condition are perceived simultaneously, and both need to be accurately reproduced simultaneously in a simulated environment in order to be properly evaluated and understood. In this work, a case is examined in which a perceived idle quality of a vehicle is addressed. In this case, two very similar vehicles, with the same powertrain but somewhat different body structures, are compared. One has a lower subjective idle quality rating than the other, despite the vehicles being so similar.
2015-06-15
Technical Paper
2015-01-2338
Dong Guo, Quan Shi, Peng Yi
In-vehicle noise is composed of a variety of tonal (frequency-related) components and the tonal components play an important role in the improvement of interior vehicle sound quality. Much research has been focused on the suppression of sound pressure level and achieved certain positive effects. However, in some operating conditions, customers still perceive the tonal components and complain about the vehicle quality even the sound pressure level is relatively low. Therefore, a better understanding of how tonal components are perceived is necessary for automotive designers. To do so, psychoacoustics results about human hearing mechanism to tonal components are comprehensively summed in this study: human hearing response to pure tone, two tones and multiple tones. Then, well-controlled testing stimuli were generated and subjective annoyance testing was conducted. The results show agreement with former researchers’ findings.
2015-06-15
Technical Paper
2015-01-2356
Huangxing Chen, David W. Herrin
The insertion loss of louvered terminations is determined using acoustic finite element analysis. The analysis is conducted in the plane wave regime and the source is anechoic. Insertion loss is determined by taking the difference between the sound power with and without the louvers at the termination. The effect of different louver configurations on insertion loss is examined. Parameters investigated include louver length, angle, spacing between louvers, and sound absorption thickness.
2015-06-15
Technical Paper
2015-01-2357
Hiromichi Tsuji, Kimihiko Nakano
In the early stage of digital phase and prototype experimental phase, the identification of the operational force on the components and the most important paths of the vibration correlated to the one of the evaluation points, such as steering, seats, and passenger ears, is required for optimizing the dynamic characteristics of the subsystem components of the vehicle. The transfer path analysis (TPA) with the impedance matrix of the component joints is widely used and reliable method to identify the force and the paths of the noise and vibration. However, the conduction of this TPA costs a lot of times. In addition, the estimated force includes not contributing to the evaluation responses. The uncorrelated force to the evaluation responses causes the design errors of the dynamic characteristics in the digital development phase. To solve the problems, a new force estimation technique is presented in this paper.
Viewing 1 to 30 of 30011