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Viewing 1 to 30 of 18351
2015-06-15
Technical Paper
2015-01-2129
Andrea Munzing, Stephane Catris
A lot of research work on icing scaling laws has been done during the last decades resulting in a today commonly accepted definition of similarity parameters and scaling laws. Those icing scaling laws have essentially been developed for fixed wing applications because airplane aerodynamic surfaces are too big to be tested in icing wind tunnels. This problem does not exist for helicopter blade profiles. However, the use of icing scaling laws is a very interesting feature in order to be able to predict ice shapes or icing performance penalty for a future helicopter still in development. Thanks to the long experience of Airbus Helicopters with icing tests a database of several real ice shapes on helicopter main and tail rotor blade sections is available. The comparison of the ice shapes obtained at the same icing similarity parameters allows the assessment of 2D icing scaling laws established for fixed wing aircrafts.
2015-06-15
Technical Paper
2015-01-2128
Enrico Bellussi
This paper describes the AgustaWestland past and present experience in the use of US Army HISS flight test results in support to the civil ice clearance for rotorcrafts. The US Army HISS is a CH47D Chinook fitted with a spray bar system providing a cloud for in flight icing evaluation with large part of the rotor (or the fuselage) of the rotorcraft immersed during the flight. The HISS allows to have flight data with stable and partially selectable ice parameters for prolonged flight time, conditions extremely difficult to encounter during natural ice flights. AgustaWestland obtained for AW139 the clearance for flight into known icing conditions (FIPS) by EASA, FAA and TCCA in 2010 and by IAC in 2011. AW139 also obtained the clearance for flight into limited ice conditions (LIPS) by EASA in 2013. In both cases the results of the US Army HISS artificial icing trials have been successfully used to support the certification process.
2015-06-15
Technical Paper
2015-01-2331
Alexander Schell, Vincent Cotoni
Aero-vibro-acoustic prediction of interior noise associated with exterior flow requires accurate predictions of both fluctuating surface pressures across the exterior of a vehicle and efficient models of the vibro-acoustic transmission of these surfaces pressures to the interior of a vehicle. The frequency range of interest varies depending on the region and source of interest. For noise transmitted through a sideglass the frequency range of interest is typically from 1-5kHz. The vibro-acoustic methods used to describe noise and vibration transmission also depend on the frequency range of interest. At higher frequencies methods like statistical energy analysis (SEA) are particularly well suited for describing the response of a trimmed cabin due to the short wavelength response of the interior acoustic space and sound package. An accurate prediction of fluctuating surface pressures also requires an accurate model of the flow over the exterior of the vehicle.
2015-06-15
Technical Paper
2015-01-2329
Paolo Di Francescantonio, Charles Hirsch, Piergiorgio Ferrante, Katsutomo Isono
The prediction of the broadband noise generated by the flow interaction with solid bodies such as for example side mirror noise, exhaust pipe noise, or ventilation and air conditioning noise require in principle the execution of extremely high demanding unsteady CFD simulations that nowadays cannot be afforded in an industrial environment. Therefore research efforts have been focused on alternative approaches that could permit to obtain engineering accurate results with much reduced computational efforts by stochastically reconstructing the turbulent velocity field starting from a steady RANS analysis. Two main families of methods have been introduced up to now, SNGR [1], and RPM[2], but applications in industrial environment are still limited mainly due to the lack of reliability of these methods and the need to introduce some tuning parameters.
2015-06-15
Technical Paper
2015-01-2349
Jiantie Zhen, David Copley, Niranjan Londhe, Scott Fredrickson
Structure-borne inputs to hybrid FEA/SEA models could have significant effects on the model prediction accuracy. The purpose of this work was to obtain the structure-borne inputs using a simplified transfer path analysis and identify the significance of the structure-borne and airborne contributions to the spectator sound power of an engine with enclosure for future modeling references. Force inputs to the enclosure from the engine were obtained and used as inputs to a hybrid engine enclosure model for sound prediction.
2015-06-15
Technical Paper
2015-01-2350
Jiantie Zhen, Scott Fredrickson
Off-highway machine mounting system isolation, especially cab mounting system, significantly affects the operator comfort by providing damping to the harsh inputs and isolating the structure-borne energy from traveling into the cab. Mounting system isolation performance is decided by not only the mount component, but also the mounting structure, and should be treated as a system. This paper gives a review of how the mounting system isolates structural energy and the effect of the mounting structures stiffness to the mounting system isolation performance.
2015-06-15
Technical Paper
2015-01-2078
Alric Rothmayer, Hui Hu
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. This sub-grid model is integrated into a covariant film mass transport model for film flow past three-dimensional surfaces of a form suitable for aircraft icing codes. Sample calculations are presented to illustrate the application of the model. Aircraft icing codes usually consist of an aerodynamic solver, a droplet trajectory solver and a mechanism to grow the ice surface. Recently, icing codes have also made use of simple models for surface water transport, typically through a film lubrication model.
2015-06-15
Technical Paper
2015-01-2327
Wind noise is one of the important NVH attributes that impacts customer sensation of vehicle interior quietness. Among many factors that influence wind noise performance, the amount of dynamic door deflection under the pressure load due to fast movement of a vehicle plays an key roll. The excessive deflection could potentially cause opened sealing gap, a.k.a. aspiration leakage, which creates a path through which the exterior aerodynamically induced noise propagates into the vehicle cabin. The dynamic door deflection can be predicted using CFD and CAE tools. This work looks into the internal pressure issue associated with the dynamic load setup during the CAE analysis. The capability of predicting the internal pressure due to high wind speed outside of a vehicle still has not been developed, and the work is based on the wind tunnel measurement involving several vehicles.
2015-06-15
Technical Paper
2015-01-2127
Andrea Munzing, Franck Hervy, Stephane Catris
A helicopter blade profile was tested in the DGA Aero-engine’s S1 icing wind tunnel in Saclay, France in winter 2013/2014. The 2D airfoil was a helicopter main rotor blade profile. Ice accretion tests have been performed to assess the profile’s time dependant aerodynamic behaviour during ice accretion. Real ice shapes were collected after each icing test. Moreover, iced profile polars were realized over a large range of angle of attack until stall. This paper presents the test set up, the test model and the test results. The test results presented in this paper are dry air and iced profile polars as well as ice shapes. The complete iced profile polars and the aerodynamic behaviour in time of the iced blade profile during ice accretion will be used for adjusting and validating prediction tools like Airbus Helicopter’s analytical iced rotor performance degradation model and they will aid to appraise the rotor loads evolution in icing conditions.
2015-06-15
Technical Paper
2015-01-2323
Abdelhakim AISSAOUI, Ravindra S Tupake, Vilas Bijwe, Mohammed Meskine, Franck Perot, Alain BELANGER, Rohit J Vaidya
F or the automotive industry, acoustic comfort is of increasing importance and changes in the market make the HVAC system noise quality a question to be addressed as early as possible during the vehicle development process. On one hand, the so-called traditional sources of annoyance such as engine, road-tires contact, exhaust systems and wind-noise have been significantly reduced for most traditional combustion engine vehicles. On the other hand, the rapid expansion of hybrid and electric vehicles and idling stop systems increases the importance of sources such as HVAC systems considered in the past as secondary. At high mass flow rate, the flow-induced contribution from the ducts and registers is the main source of noise in the mid to high frequency ranges and is more important than the HVAC structure borne and blower engine contributions.
2015-06-15
Technical Paper
2015-01-2345
Arnaud Duval, Valérie Marcel, Ludovic Dejaeger, Francis Lhuillier, Moussa Khalfallah
The Flaxpreg™ is a green and light very long flax fibers thermoset reinforced sandwich, that can be effectively used as multi-position trunk loadfloor or structural floor in the passenger compartment of a vehicle. The prepreg FlaxTapes© of about 120 g/m² constituting the skins of the sandwich, are unidirectionally aligned flax fibers tapes, with acrylic resin here, easily manipulable without requiring any spinning or weaving step and thus without any negative out of plane crimping of the almost continuous flax fibers. Thank to their very low 1,45 density combined with an adaptative 0°/90°/0° orientation of the FlaxTapes© (for each skin) depending on the loading boundary conditions, the resulting excellent mechanical properties allow a – 35% weight reduction compared to petro-sourced Glass mat/PUR sandwich solutions (like the Baypreg).
2015-06-15
Technical Paper
2015-01-2079
Colin Hatch, Jason Moller, Eleftherios Kalochristianakis, Ian Roberts
Summary The size and shed time of ice shed from a propeller is predicted using a process that determines ice shape, ice growth rate and both internal and ice-structure interface stresses. A brittle failure damage model is used to predict the onset of local failure and to propagate damage in the ice until local ice shedding is obtained. Background Research into suitable ice-phobic coatings as a potential approach in an integrated aircraft ice protection system (IPS) has been ongoing for many years. Durability of these coatings has been an issue; however future research programmes such as the EU programmes AEROMUCO [1] and STORM [2] are looking to improve the Technology Readiness Level (TRL) of the application of these types of coatings. The introduction of ice-phobic coatings may make it possible to provide ice protection on rotating surfaces without the need for specialist ice protection systems.
2015-06-15
Technical Paper
2015-01-2121
Yong Chen, Liang Fu
In helicopter, the icing rotor blades will decrease the effectiveness of the helicopter and endanger the lives of the pilots. The asymmetrical ice break-up and shedding could also lead to severe vibrations of the rotor blade. Ice break-up from the main rotor may strike the fuselage and tail rotor, even worse, find its way into the engine, which may cause serious aircraft accidents. An understanding of the mechanisms responsible for ice shedding process is necessary in order to optimize the helicopter rotor blade design and de-icing system to avoid hazardous ice shedding. In previous study, the ice shedding criteria was established by comparing the centrifugal force and the adhesion force. In most cases, part of the ice will shed before the centrifugal force equals to the adhesion force, because the adhesion stress between the ice and the blade is not uniform.
2015-06-15
Technical Paper
2015-01-2102
Guilin Lei, Wei Dong, Jianjun Zhu, Mei Zheng
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
2015-01-2118
Sergey Alekseyenko, Michael Sinapius, Martin Schulz, Oleksandr Prykhodko
In spite of wide theoretical and experimental studies of icing problem that have been held up to recent times, nevertheless, the most dangerous flights regimes as in the presence of supercooled large droplets or in supercooled rain remain studied not enough. Also the range of parameters that corresponds to the exploitation modes of aircrafts with relatively small heights and speeds of flight like airplanes of small aviation, helicopters, UAV etc. because of the complexity of the icing processes are still not covered. The aim of this work is to answer the next question: which an actual process of interaction of supercooled large water droplets with growing ice surface at small speeds of flight and which physics of falling moisture freezing process on the icing surface is. Thus, the work presents the results of experiments conducted in order to obtain the photographic data on how the interaction between the supercooled water droplets and the icing aerodynamic surface occurs.
2015-06-15
Technical Paper
2015-01-2080
Roger J. Aubert
While the industry is making consistent progress in predicting aerodynamic performance impact from ice accretion on rotor blade and ability to reliably design thermal anti-icing and/or deicing protection systems, ice shedding, natural or induced, is trailing behind both in terms of understanding the physics of impact ice adhesion and cohesion, mechanical fracture and energy dissipation upon impact on airframe or rotor systems. It is only recently that attention dedicated to the understanding of impact ice shedding on rotors has increased. Reference 1 summarizes the mechanical properties of ice. However, more recent test results (Reference 2 and 3) showed different results. It was therefore concluded that a data base more representative of helicopter operation was necessary. It is the intent of this paper to summarize the differences in test results and provide additional considerations for analytical modeling of the ice shedding process on a rotor blade.
2015-06-15
Technical Paper
2015-01-2088
Richard E. Kreeger, Lakshmi Sankar, Robert Narducci, Robert Kunz
The formation of ice over lifting surfaces can affect aerodynamic performance. In the case of helicopters, this loss in lift and the increase in sectional drag forces will have a dramatic effect on vehicle performance. The ability to predict ice accumulation and the resulting degradation in rotor performance is essential to determine the limitations of rotorcraft in icing encounters. The consequences of underestimating performance degradation can be serious and so it is important to produce accurate predictions, particularly for severe icing conditions. The simulation of rotorcraft ice accretion is a challenging multidisciplinary problem that until recently has lagged in development over its counterparts in the fixed wing community. But now, several approaches for the robust coupling of a computational fluid dynamics code, a rotorcraft structural dynamics code and an ice accretion code have been demonstrated.
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou
At high cruising speed, the car A-pillars generate turbulent air flow. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled. This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior turbulent field using an unsteady CFD solver (EXA PowerFlow); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (Actran). The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment (porous material, damping layer). A pure vibro-acoustic model with hammer shock excitation on a window is first built.
2015-06-15
Technical Paper
2015-01-2123
Eric Defer, Jean-Louis Brenguier, Jos De Laat, Julien Delanoe, Fabien Dezitter, Michael Faivre, Amanda Gounou, Alice Grandin, Anthony Guignard, Jan Fokke Meirink, Jean-Marc Moisselin, Frederic Parol, Alain Protat, Claudine Vanbauce
J.-L. Brenguier (1), J. De Laat (2), P. De Valk (2), E. Defer (3), J. Delanoë (3), F. Dezitter (4), M. Faivre (3), A. Gounou (1), A. Grandin (4), A. Guignard (3), J. F. Meirink (2), J.-M. Moisselin (1), F. Parol (3), C. Vanbauce (3) 1 - Météo-France 2 - KNMI 3 - CNRS 4 - AIRBUS The European FP7 High Altitude Ice Crystals (HAIC) project aims at characterizing specific environmental conditions in the vicinity of convective clouds that can lead to in-service events [1]. Academics and aeronautic industries are collaborating within 6 main research activities that include dedicated field campaigns, development of new in situ probes, space-based detection and monitoring, upgrade of on-board weather radars, improvement of ground test facilities, and modeling of melting and impingement processes. All activities are designed to enhance aircraft safety when flying in mixed phase and glaciated icing conditions.
2015-06-15
Technical Paper
2015-01-2328
Barbara Neuhierl, Sivapalan Senthooran, Reinier Toppinga, Anke Jäger, Maarten Brink, Timo Lemke, Philippe Moron, Raghu Mutnuri
The object of the validation study presented in this paper is a generic vehicle, the so-called SAE body, developed by a consortium of german car manufacturers (Audi, Daimler, Porsche, Volkswagen). It consists of a simplified cabin whose interior can be equipped with either reverberant or partly absorbing walls. To obtain more realistic flow and pressure excitation typical for production vehicles, an a-pillar and a series rear view mirror were attached to the exterior surface. Furthermore the test object contains a glass side window, allowing noise transmission to the interior. Many experiments have been performed by the abovementioned consortium on this object in the past to investigate its behavior when exposed to fluid flow. Some of these experiments were used to validate the simulation results discussed in the present paper.
2015-06-15
Technical Paper
2015-01-2324
Hangsheng Hou, Guiping Yue
When a sunroof opens to let the fresh air in during driving, there might be several noise issues associated with it. The most common and important one is the wind throb issue, which is normally resolved by installing a wind deflector with sufficient height. However with the wind throb issue gone, other sound quality problems may surface. The most obvious one is the hissing noise, which occurs often in higher speed range. This work investigates a sunroof deflector deployment strategy considering wind throb, hissing noise and other psychoacoustic attributes that could be felt subjectively by a customer. The goal is to optimize sound quality associated with an open sunroof, potentially targeting the most NVH demanding customers in the premium vehicle segment.
2015-06-15
Technical Paper
2015-01-2124
Amanda Gounou, Jean-Marc Moisselin, Frédéric Autones, Dominique Levaillant, Jean-Louis Brenguier, Eric Défer, Michael Faivre, Alice Grandin, Fabien Dezitter, Sandra Turner
Icing conditions are often encountered in the vicinity of deep convective clouds. Nowcasting of these conditions would be of a great help for flight safety and air traffic management but still remains challenging. In the framework of the HAIC (High Altitude Ice Crystals) project [1], the nowcasting of icing conditions due to ice particles is investigated. A major field campaign has been carried out in Darwin, Australia, from 16th January to 7th March 2014, during the rainy season to sample meteorological conditions potentially leading to icing [2]. There were 23 research flights with on-board in-situ and remote sensing instruments measuring or estimating ice water content within oceanic mature thunderstorms which offered a great opportunity to implement, test and cross-validate nowcasting tools to detect and track cloud regions of high ice water content.
2015-06-15
Technical Paper
2015-01-2148
Erdem Ayan, Serkan Ozgen, Canibek Murat, Erhan Tarhan
Ice crystal ingestion to aircraft engines may cause ice to accrete on internal components, leading to flameout, mechanical damage, rollback, etc. Many incidents occur due to the engine failures especially at high altitude convective weather conditions. Thus, in the framework of HAIC FP7 European project, the physical mechanisms of ice accretion on surfaces exposed to ice-crystal and mixed-phase conditions are investigated. Within the HAIC FP7 European project, TAI will implement models related to the ice crystal accretion calculation to the existing ice accumulation prediction program for droplets, namely TAICE. Considered models include heat transfer & phase change model, drag model and impact model. Moreover, trajectory model and Extended Messinger Model require some modifications to be used for ice crystal accretion predictions.
2015-06-15
Technical Paper
2015-01-2325
Paul Bremner, Chris Todter, Scott Clifton
Title: Sideglass Turbulence and Wind Noise Sources Measured with a High Resolution Surface Pressure Array Authors: Paul Bremner – AeroHydroPLUS, Del Mar CA 92104 USA Chris Todter – Keppel Professional Services, San Diego CA 92107 Scott Clifton – c/o AeroHydroPLUS, Del Mar CA 92104 USA The authors report on the design and use of high resolution micro-electro-mechanical (MEMS) microphone arrays for automotive wind noise engineering. The arrays integrate both sensors and random access memory (RAM) chips on a flexible circuit board that eliminates high channel count wiring and allows the array to be deployed on automobile surfaces in a convenient “stick-on/peel-off” configuration. These arrays have application to the quantitative evaluation of interior wind noise from measurements on a clay model in the wind tunnel, when used in conjunction with a body vibro-acoustic model.
2015-06-15
Technical Paper
2015-01-2250
Masahiro Akei, Nobutaka Tsujiuchi, Akihito Ito, Takayuki Yamauchi, Daisuke Kubota
This paper describes the identification of the sound source model for the diesel engine installed on the agricultural machine by Inverse-Numerical Acoustic analysis (INA), and the noise prediction using the sound source model identified by INA. INA is a method to identify surface vibrations from surrounding sound pressures. This method is applicable for a complicated-shaped sound source like an engine. Although many studies about INA have been conducted, these past studies are the studies on improvement of the identified accuracy and noise prediction in the free sound field or hemi-free sound field. The authors predicted accurately sound pressure level of engine enclosure using sound source model identified by INA and boundary element method (BEM). However, we have not yet verified the effectiveness of sound source model against the enclosure which has an absorption material and an opening.
2015-06-15
Technical Paper
2015-01-2342
Jun Zhang, Jian Pang, Siwen Zhang, Xiaoxuan Zhang, Congguang Liu
A Lightweight Dash Insulator Development and Engineering Application for the Vehicle NVH Improvement Jun ZHANG 1,2 , Jian PANG 1,2,*, Cong-guang LIU 1,2, Xiao-xuan ZHANG 1,2, 1 Changan Auto Global R&D Center NVH Department, Chongqing, China, 401120 2. State Key Laboratory of Vehicle NVH and Safety Technology, Chongqing, China,, 401120 * Correspondence author, e-mail address: pangjian@changan.com.cn ABSTRACT The lightweight design for sound package is becoming more and more important in automobile development. The research on lightweight sound package has become one of the hot topics in automobile industry. This paper presents a procedure to develop lightweight dash insulator based on NVH targets. The mechanism to reduce dash panel weight and to improve sound insertion loss simultaneously is described in this paper. The paper illustrates a new lightweight dash insulator structure with surface density 2500g/mm2.
2015-06-15
Technical Paper
2015-01-2261
Joseph Plattenburg, Jason Dreyer, Rajendra Singh
Combined active and passive damping is an emerging trend as it should be an effective solution to challenging NVH problems, especially for lightweight vehicle components that demand advanced noise and vibration treatments. Compact patches are of particular interest due to their small size and cost; however, improved modeling techniques are needed for such methods. This paper presents a refined modeling procedure for side-by-side active and passive damping patches applied to thin, plate-like powertrain casing structures. As an example, a plate with fixed boundaries is modeled as this is representative of real-life transmission covers which often require damping treatments. Further scientific studies include a bench experiment that determines frequency dependent properties of the viscoelastic damping material. The proposed model is then utilized to examine several cases of active and passive patch location, and vibration reduction is determined in terms of insertion loss for each case.
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
2015-01-2321
Nicholas Oettle, Andrew Bissell, Sivapalan Senthooran, Mohammed Meskine
Car manufacturers put large efforts into reducing wind noise to improve the comfort level of their cars. Each component of the vehicle is designed to meet its individual noise target to ensure the wind noise passenger comfort level inside the vehicle is met. Sunroof designs are tested to meet low-frequency buffeting targets as well as broadband noise targets for the sunroof in vent position and any noise generated by deflectors. Experimentally testing designs and making changes to meet these design targets typically involves high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the use of a reliable numerical prediction capability early in the vehicle design process.
2015-06-15
Technical Paper
2015-01-2326
Denis Blanchet, Anton Golota
Recent developments in the prediction of the contribution of wind noise to the interior SPL have opened a realm of new possibilities. The main physical mechanisms related to noise generation within a turbulent flow and transmission through the vehicle greenhouse are nowadays better understood. Several simulation methods such as CFD, FEM, BEM, FE/SEA Coupled and SEA can be coupled together to represent the physical phenomena involved. The main objective being to properly represent the convective and acoustic component within the turbulent flow to ensure proper computation of the wind noise contribution to the interior SPL of a vehicle. This paper presents comparisons between simulations results and measurements for various configurations such as i) with and without mirror, ii) various A-Pillar shapes, iii) various vehicle speeds and finally iv) various yaw angles.
Viewing 1 to 30 of 18351