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Viewing 1 to 30 of 104294
2015-07-01
Journal Article
2015-01-9110
Klementina Gerova, Anthony Savill
Abstract The simulation of heat exchanger air flow characteristics using Computational Fluid Dynamics requires knowledge of the experimental pressure drop across the element concerned. This is normally achieved through wind tunnel testing of either full scale heat exchangers or by using laminations of various porous materials and honeycombs to represent these. The current paper both continues and compliments prior work published by the lead author, which entailed a series of measurements of the pressure drop in both the near and far field, across screens with porosity (β) in the range 0.41 < β < 0.76. This experimental investigation established a relationship between the porosity and the pressure drop characteristics of a given material at various angles of inclination to the free-stream flow. In addition, the effect of screen depth was investigated using honeycombs.
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
2015-01-2132
David L. Rigby, Joseph Veres, Colin Bidwell
Three dimensional Navier-Stokes simulations of the Honeywell ALF502 low pressure compressor using the NASA Glenn code Glenn-HT have been carried out. A total of eight operating points were investigated. These operating points are at, or near, points where engine icing has been determined to be likely. The results of this study are expected to be used immediately, and in the future, for further analysis such as predicting collection efficiency of ice particles and ice growth rates at various locations in the compressor. A mixing plane boundary condition is used between each blade row, resulting in convergence to steady state within each blade row. Results for two levels of approximation are discussed. The first set of cases were run allowing all of the solid surfaces to slip (i.e. inviscid). That is, the velocity boundary layers are not resolved. This allows for much smaller grids and shorter run times.
2015-06-15
Technical Paper
2015-01-2131
Colin Bidwell, David Rigby
A flow and ice particle trajectory analysis was performed for the booster of the Honeywell ALF502 engine. The analysis focused on two closely related conditions one of which produced an icing event and another which did not during testing of the ALF502 engine in the Propulsion Systems Lab (PSL) at NASA Glenn Research Center. The flow analysis was generated using the NASA Glenn GlennHT flow solver and the particle analysis was generated using the NASA Glenn LEWICE3D v3.61 ice accretion software. The inflow conditions for the two conditions were similar with the main difference being that the condition that produced the icing event was 6.8 K colder than the non-icing event case. The particle analysis, which considered sublimation, evaporation and phase change, was generated for a 5 micron ice particle with a sticky impact model and for a 24 micron, 7 bin ice particle distribution with an SLD splash model used to simulate ice particle breakup.
2015-06-15
Technical Paper
2015-01-2134
Tom Currie, Dan Fuleki
There is significant recent evidence that ice crystals ingested by a jet engine at high altitude can partially melt and then accrete within the forward stages of the compressor, potentially producing a loss of performance, rollback, combustor flameout, compressor damage, etc. Several studies of this ice crystal icing (ICI) phenomenon have been conducted in the past 5 years using the RATFac (Research Altitude Test Facility) altitude chamber at the National Research Council of Canada (NRCC), which includes an icing wind tunnel capable at operating at Mach numbers (M), total pressures (po) and temperatures (To) pertinent to ICI. Humidity can also be controlled and ice particles are generated with a grinder. The ice particles are entrained in a jet of sub-freezing air blowing into the tunnel inlet. Warm air from the altitude cell also enters the tunnel, where it mixes with the cold ice-laden jet, increasing the wet-bulb temperature (Twb) and inducing particle melting.
2015-06-15
Technical Paper
2015-01-2133
Joseph P. Veres, Scott M. Jones, Philip C. E. Jorgenson
The Propulsion Systems Laboratory (PSL), an altitude test facility at NASA Glenn Research Center, has been used to test a full scale turbine engine at simulated altitude operating conditions. The PSL test facility has the capability to create a continuous cloud of ice crystals that are ingested by the engine during operation at simulated altitudes. The PSL tests successfully duplicated the icing events that were experienced by this engine during flight through ice crystal clouds. During testing at the PSL, after the ice cloud was turned on, key engine performance parameters responded immediately due to ingestion of the ice crystals. The points where the performance deteriorated with time have been attributed to ice accretion in the low pressure compressor. Eight data points were analyzed in order to gain understanding of key transient engine performance parameters. Examination of the test data showed two distinct responses in the engine once the ice cloud was initiated.
2015-06-15
Technical Paper
2015-01-2136
Francisco José Redondo
Due to weight constraints, the engine air intake for the Airbus A400M Transport Airplane will be all made in aluminum, and by specification, the intake is protected against ice accretion by a hot air system. In order to assure a fatigue life of the element for the life of the airplane, the temperature of the air supplied must be controlled to a maximum value consistent with aluminum characteristics. A system has been designed wherein hot air is bled and cooled by coolant air from inside the nacelle with a jet pump.While maximum temperature was a constraint for the design of the system, several other constraints appeared during the detailed design of the system; - the tight space allocation inside the nacelle limited the length of the jet pump, - the low temperature provided by the engine bleed in flight idle limited the secondary flow used to cool the engine bleed, and - the complex air distribution needed to supply air to the intake areas. Two variants of the system were developed.
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
2015-01-2144
James MacLeod, Michael Clarke, Doug Marsh
The GLACIER Icing Facility – Lessons Learnt in the first Five Years of Operation J.D. MacLeod M. Clarke National Research Council of Canada Rolls-Royce plc Gas Turbine Laboratory Civil Aerospace Ottawa, ON Derby, UK Abstract The Global Aerospace Centre for Icing and Environmental Research Inc. (GLACIER) facility is located in Thompson, Manitoba, Canada. This facility provides icing certification tests for large gas turbine engines, as well as performance, endurance and other gas turbine engine qualification testing. This globally unique outdoor engine test and certification facility was officially opened back in 2010. The prime purpose of this facility is for icing certification of aero gas turbines. The facility provides the aviation industry with the required environmental conditions (by virtue of its location), and the capability to meet the growing demands for icing certifications and other adverse cold weather conditions.
2015-06-15
Technical Paper
2015-01-2137
Daniel R. Adriaansen, Paul Prestopnik, George McCabe, Marcia Politovich
Advancements in numerical weather prediction (NWP) modeling continue to enhance the quality of in-flight icing forecasts and diagnoses. When performing a diagnosis of current in-flight icing conditions, observational datasets can be combined with NWP model output to form a more accurate representation. These diagnoses are traditionally tied to a three-dimensional grid, typically the grid of the NWP model data chosen for use. Surface observations are heavily relied upon when performing in-flight icing diagnoses 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 grid. For example, we seek an improved solution to the problem of combining point-based METARs observations with NWP model grids over the current method.
2015-06-15
Technical Paper
2015-01-2294
Kodali Ajay Krishna, Pankaj Bhardwaj, Sanjeevgouda Patil, Mansinh Kumbhar
One of the primary excitation sources in a passenger car comes from the powertrain [1]. Refinement of powertrain induced noise is one of the major tasks during a full vehicle NVH refinement. For better fuel efficiency and emission norms, vehicle manufacturers need to focus drastically on reducing the weight and also at the same time achieving defined NVH targets. Due to ever increasing demand for reducing the development cycle of the design, most critical decisions have to be made at the concept stage of the powertrain design itself. Combustion excitation forces and powertrain radiated noise are the most important design factors along with the thermal, durability, and strength requirements that must be evaluated during concept stage and also during other stages of the development process. Solution time for calculating the radiated noise using the existing acoustic solvers is very high and requires very expensive resources (software and hardware).
2015-06-15
Technical Paper
2015-01-2291
Pandurang Maruti Jadhav, Sandesh A Dunung, Pravin T Nitnaware
There are many environmental issues in India. Air pollution, water pollution, garbage, vibration & noise pollution and pollution of the natural environment are all challenges for India. India has a long way to go to reach environmental quality similar to those enjoyed in developed economies. Pollution remains a major challenge and opportunity for India. The review of trends in farm practices and machinery development suggests that vibration & noise problems are still prevalent in agricultural situations, even though there has been a steady increase in the availability of materials and equipment for vibration & noise control over recent years. Diesel engine is the main source of power for agricultural equipments, such as water pump set, compressor, electric generator and tractor. Even it is one of the sources of vibration & noise in agricultural field. There is reluctance of the agricultural sector to use of vibration & noise control methods.
2015-06-15
Technical Paper
2015-01-2297
Insoo Jung, Jaemin Jin, Kwangmin Won, Seungwook Yang, Kyoungdoug Min, Hoimyung Choi
Combustion noise of diesel engine can be deteriorated by combustion characteristics that are influenced by the factors such as engnine NVH durability, driving conditions, environmental factors and fuel properties. Therefore we need to develop robust combustion noise to be insensitive to the factors. To achieve this purpose, the method for combustion characteristics prediction has been developed by means of analyzing vibration signal measured from engine cylinder block. The closed-loop control by controlling injection parameters through combustion characteristics prediction has been carried out to make combustion characteristics that we want to exhibit. We have also evaluated the effect of combustion noise and fuel consumption by applying the closed-loop control.
2015-06-15
Technical Paper
2015-01-2310
Edward Ray Green
The Sound Transmission Loss of automotive intake and exhaust components is commonly measured using the four microphone tube method per ASTM E2611. Often area adapters are used to match the component tube to that of the tube apparatus. These area adapters affect the Sound Transmission Loss measurement, especially at very low frequencies. The use of the Transfer Matrix Technique to remove the affect of the area adapters is described. The improvements for step and cone area adapters are compared.
2015-06-15
Technical Paper
2015-01-2317
Zhenlin Ji, Yiliang Fan
A simulation program named as MAP (Muffler Analysis Program) is developed for the rapid calculation and analysis of acoustic characteristics of duct muffling systems. The program is based on the plane wave theory and uses the Visual Basic 6.0 to create a friendly GUI (Graphic User Interface) for input of the geometrical and physical parameters to build and modify the duct muffling systems quickly. The relation among the duct acoustic elements is established by using the transfer matrix method, and the Transmission Loss (TL) and Insertion Loss (IL) may be calculated, and then the results are plotted in terms of curve. Map allows designer to change parameters of the duct muffling systems expediently, to investigate the effects of design changes on the acoustic characteristics and finally to get an acceptable solution.
2015-06-15
Technical Paper
2015-01-2311
Aditya Palsule, Arun Budama, Nandakumar Somasundaraeswer
Development of split Catcon-Muffler system was done to be used in front engine low floor (FELF) bus from perspective of cost saving, modularity and reduction in complexity. This system is developed as an alternate to an existing solution of integrated Catcon and muffler. The paper describes the development of a split Catcon and muffler exhaust system for a FELF bus, so as to meet cost and time considerations. The development had to achieve a feasible muffler + catalytic converter solution, which could be installed within the packaging volume of the existing configuration, while meeting the regulatory requirements for Pass by noise (PBN), and at the same time conforming to backpressure limits set for optimum engine performance. Multiple design – prototypes – test iterations were carried out to meet the PBN and back pressure target of engine. The final solution was developed which achieved both the requirements within the specified space constraints.
2015-06-15
Technical Paper
2015-01-2313
Bryce Gardner, Abderrazak Mejdi, Chadwyck Musser, Sébastien Chaigne, Tiago De Campos Macarios
Flow strongly affects the propagation of acoustics wave transmission within a duct and this must be addressed by the vibro-acoustic modelling of duct systems subject to uniform or non-uniform flow. Flow impacts both the effective sound propagation speed in a duct and refracts the sound towards or away from the duct walls depending on whether the acoustic waves are propagating in the direction of the flow or against the flow. Accurate modeling of the acoustic propagation within a duct is crucial for design and “tuning” of muffler systems that need to strongly attenuate narrowband acoustic sources from the engine. Muffler systems that may avoid matching acoustic resonances to engine narrowband sources when no flow is present may experience shifting of resonances to frequencies that match engine sources and cause problems when the flow during a real operating condition is present.
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.
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
2015-01-2346
Balakumar Swaminathan
From a facility perspective, engine test cells are rarely evaluated for their vibration levels in their functional configuration. When complicated dynamic systems such as an internal combustion engine and a dynamometer are coupled together using driveshafts and coupling components, the overall system behavior is significantly different from that of the individual sub-systems. This paper details an instance where system level experimental testing and finite element analysis methods were used to mitigate high vibration levels in an engine test cell. Modal and operational test data were taken to establish baseline vibration levels at a diesel engine test cell during commissioning. Measurements were taken on all major sub-systems such as the engine assembly, dynamometer assembly, intermediate driveshaft bearing pedestal and driveshaft components.
2015-06-15
Technical Paper
2015-01-2344
Murteza T. Erman
In today’s world automotive manufacturers are required to decrease CO2 emissions and increase the fuel economy while assuring driver comfort and safety. To achieve desired acoustic performance targets, automotive manufacturers use various Noise-Vibration-Harshness (NVH) materials which they apply to the vehicle structure either in paint shop or assembly shop. Beside sound deadening coatings applied onto underbody of vehicles they use also either constrained or not-constrained layer of sheets. The majority of these sheets are applied onto floor pan inside the vehicle, known as asphalt-sheets. These asphalt-sheets are highly filled systems with high specific gravity and depending on vehicle 10~20 kg/vehicle application is common. Since early 1990’s, automotive manufacturers also have introduced so called Liquid-Applied Sound Damping materials (LASD).
2015-06-15
Technical Paper
2015-01-2341
Marc Ingelmann, Holger Bickelmann
BASF supplies the automotive industry with parts made of the Micro-cellular Polyurethane Elastomer - Cellasto®, a material with unique characteristics in NVH applications. For over 50 years our automotive customers are relying on our materials, with the Jounce Bumper being our best known applications. Top mounts and coil-spring-isolators are also a key offering to the industry. A lot of functions in automotive and non-automotive products are using Cellasto® as damping element, such as armrests, seats, torque-dampers, handheld machines etc. The dynamic performance of Cellasto , combined with the ability to work in limited packages, makes it the ideal choice. The amplitude selective damping fits to the automotive requirements: small amplitudes are generating a low damping of the material; high amplitudes are increasing the damping.
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
2015-01-2347
James A. Mynderse, Alexander Sandstrom, Zhaohui Sun
Mechanical engineering students at Lawrence Technological University (Lawrence Tech) must complete a capstone project, some of which are industry-sponsored projects (ISPs). American Axle & Manufacturing Inc. (AAM) partnered with LTU to provide a senior design experience in NVH through a proposed improvement to the AAM driveline dynamometer. AAM proposed that students design, develop, and fabricate a decoupling mechanism that minimizes the vibration disturbances transmitted from the driver shaft to the driven shaft. This work describes the LTU-AAM partnership, the design problem and the completed decoupler mechanism with experimental validation. The AAM driveline dynamometer provides immense value for experimental validation of product NVH performances. It has been intensively used to evaluate product design robustness in terms of build variations, mileage accumulation, and temperature sensitivity.
2015-06-15
Technical Paper
2015-01-2361
Sajjad Beigmoradi
Nowadays, by the introduction of significant advances in automotive industries, noise, vibration and harshness (NVH), in the position of the main comfort attribute, plays a crucial role in marketing and passenger satisfaction. In order to cope NVH problems, three main actions are taken by NVH engineers for reducing perceived level of noise in cabin: Noise reduction in sources, Noise path treatment and Noise control at receiver. Among these approaches, those pertain to modification of noise pass, through structure and air, to the cabin are more prevalent in automotive applications. Accordingly, identification of noise paths that dominantly contribute to sound and vibration transfer to cabin phenomenon should be dealt with importance. In practice, engine vibration transmitted through sub-frame attachments to body can induce high level of noise and vibration to the passenger cabin.
2015-06-15
Technical Paper
2015-01-2359
Craig Reynolds, Jason Blough, Carl Anderson, Mark Johnson, Jean Schweitzer
Sound power is commonly estimated using either a reverberant chamber or an anechoic environment as described by the ISO 3741:2012 and ISO 3744:2012 standards respectively. Both methods require the volume of the noise source to be less than 1% of the chamber volume leading to a requirement of relatively large test chambers. Torque converter cavitation noise testing in an enclosed metallic test fixture violates both standards due to volume and/or space requirements. This paper describes a new method developed to accurately determine torque converter sound power through characterization of the test environment. Two types of reference noise sources were created to represent torque converter geometries and noise output. A tweeter was used to output broadband high frequency noise typical of cavitation noise. The first source consisted of the torque converter cover and tweeter only. The second used the cover and pump with a tweeter in place of the turbine, stator, and clutch.
2015-06-15
Technical Paper
2015-01-2358
Rod Morris-Kirby, Evan Harry, Dirk Jaeger, Bernd Borgmann
Acoustic Diagnostic Network Algorithms (DNA) are experimental methods that extract airborne acoustic characteristics from a motor vehicle and decompose this information into a set of networks from which the source, path and receiver noise sources and paths can be determined. Unlike traditional transfer path analysis Acoustic DNA takes the problem into the fine detail and answers questions such as what, where and how does a vehicle system need to be changed in order to achieve any given objective. This paper describes the fundamental methodology and features together with how it has been implemented into a user friendly computer program that has been used successfully in over 50 vehicle projects within the Adler Pelzer group on a wide range of motor vehicles.
2015-06-15
Technical Paper
2015-01-2367
David Lennström, Arne Nykänen
The number of electric vehicle models has significantly grown in the last few years. Most of the car manufacturers can today offer pure electric or some type of hybrid electric alternatives. When it comes to the acoustic properties of electric cars, the powertrain noise differs dramatically compared to traditional vehicles with internal combustion engines. The low frequency firing orders, mechanical and combustion noise are exchanged with a more high frequency whining signature due to electromagnetic forces and gear whine, lower in level but subject to annoyance. Previous papers have highlighted these differences and also investigated perception criteria in terms of psycho-acoustic metrics. However, investigations of differences between different kinds of electric and hybrid electric cars are still rare. In this study, 13 electrified cars on the market were analyzed in order to obtain a broadened view of the tonal compositions.
2015-06-15
Technical Paper
2015-01-2365
Zhaohui Sun, Glen Steyer, Jason Ley
Alternative powertrains, in particular electric and plug-in hybrids, create a wide range of unique and challenging NVH issues in today’s automotive industry. Among the emerging engineering challenges from these powertrains, their acoustic performances become more complicated, partially due to reduced ambient masking noise level and light weight structure. In addition, the move away from conventional displacement engines to electrical drive units has created a new array of NVH concerns and dynamics, which are relatively unknown as compared to the aforementioned traditional setups In this paper, an NVH optimization study will be presented, focusing on four distinct factors in EDU gear mesh source generation and radiation: EDU housing and bearing dynamics, gear geometry, EDU shafting torsional dynamics, and EDU housing structure. The study involves intensive FEA modeling/analyses jointly with physical validation tests.
2015-06-15
Technical Paper
2015-01-2364
Xianpai Zeng, Jared Liette, Scott Noll, Rajendra Singh
The vibration isolation effectiveness of powertrain mount configurations is examined for electric vehicle application by focusing on the deteriorating effect introduced by internal mount resonances. Unlike internal combustion engines where mounts are typically designed only for static support and low frequency dynamics, electric motors have higher excitation frequencies in a range where mount resonances often occur. The problem is first analytically formulated by considering a simple 2-dimensional powertrain system. It is shown that by modifying the mount shape, the mount resonance(s) can be shifted while maintaining the same static rate. Further, vibration isolation is improved over a narrow frequency range by using non-identical mounts that split mount resonance peaks. Then a computational model for a realistic drive unit (containing electric motor, power invertor, and differential case) is considered.
Viewing 1 to 30 of 104294