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Viewing 1 to 30 of 61087
2011-05-17
Journal Article
2011-01-1649
Andrew J. Morello, Jason R. Blough, Jeffrey Naber, Libin Jia
Research into the estimation of diesel engine combustion metrics via non-intrusive means, typically referred to as “remote combustion sensing” has become an increasingly active area of combustion research. Success in accurately estimating combustion metrics with low-cost non-intrusive transducers has been proven and documented by multiple sources on small scale diesel engines (2-4 cylinders, maximum outputs of 67 Kw, 210 N-m). This paper investigates the application of remote combustion sensing technology to a larger displacement inline 6-cylinder diesel with substantially higher power output (280 kW, 1645 N-m) than previously explored. An in-depth frequency analysis has been performed with the goal of optimizing the estimated combustion signature which has been computed based upon the direct relationship between the combustion event measured via a pressure transducer, and block vibration measured via accelerometers.
2011-05-17
Technical Paper
2011-01-1644
Greg Uhlenhake, Ahmet Selamet, Kevin Fogarty, Kevin Tallio, Philip Keller
A cold turbocharger test facility was designed and developed at The Ohio State University to measure the performance characteristics under steady state operating conditions, investigate unsteady surge, and acquire acoustic data. A specific turbocharger is used for a thermodynamic analysis to determine the capabilities and limitations of the facility, as well as for the design and construction of the screw compressor, flow control, oil, and compression systems. Two different compression system geometries were incorporated. One system allows compressor performance measurements left of the surge line, while the other incorporates a variable-volume plenum. At the full plenum volume and a specific impeller tip speed, the temporal variation of the compressor inlet and outlet and the plenum pressures as well as the turbocharger speed is presented for stable, mild surge, and deep surge operating points.
2011-05-17
Technical Paper
2011-01-1645
Michael Browne
Test Facilities for Vibrations and Acoustics can be very complicated. With the addition of necessary high power motor dynamometers for load application, the complexity of the test cell increases dramatically. The motors and subsequent additional fixtures and shafts necessary to apply loading conditions can produce additional source noises that would interfere with test measurements. In addition, facility interfaces can dramatically influence the test cell setup and reduce the measurement capabilities. This paper addresses common considerations needed in considering a new test cell for driveline vibration, acoustics, efficiency, and durability testing using motored dynamometers. In addition to outlining common design points, a practical application of 2 new dynamometers utilized for vibration, acoustics, efficiency, and durability testing and their subsequent capabilities are outlined.
2011-05-17
Technical Paper
2011-01-1660
Ienkaran Arasaratnam, Saeid Habibi, Christopher Kelly, Tony J. Fountaine, Jimi Tjong
Advanced engine test methods incorporate several different sensing and signal processing techniques for identifying and locating manufacturing or assembly defects of an engine. A successful engine test method therefore, requires advanced signal processing techniques. This paper introduces a novel signal processing technique to successfully detect a faulty internal combustion engine in a quantitative manner. Accelerometers are mounted on the cylinder head and lug surfaces while vibration signals are recorded during engine operation. Using the engine's cam angular position, the vibration signals are transformed from the time domain to the crank-angle domain. At the heart of the transformation lies interpolation. In this paper, linear, cubic spline and sinc interpolation methods are demonstrated for reconstructing vibration signals in the crank-angle domain.
2011-05-17
Technical Paper
2011-01-1662
Chad Walber, Jason R. Blough, Mark Johnson, Carl Anderson
When testing dynamic structures, it is important to note that the dynamic system in question may be submerged into a fluid during operation and to properly test the structure under the same condition in order to understand the true dynamic parameters of the system. In this way, the mass and stiffness coupling to the particular fluid, for the case of this study, automatic transmission fluid, may be taken into account. This is especially important in light structures where the coupling between the fluid mass and the structural mass may be great. A structure was tested with a laser vibrometer using several impact methods in open air to determine which impact method would be most suitable for submerged testing. The structure was then submerged in transmission fluid with an accelerometer attached and subsequently tested and compared to the previous results.
2011-05-17
Technical Paper
2011-01-1619
Shi Zheng, Chris Kleinfeld
This paper presents a hybrid method that predicts the whistle occurrence of an automotive exhaust tuning device. The method utilizes inputs from a limited amount of test work or numerical simulation to predict the whistle occurrence in a wider range of flow conditions (temperature and velocity). It has the advantages of being quick and low cost compared with extensive tests or the computational fluid dynamics approach.
2011-05-17
Technical Paper
2011-01-1639
Jan Krueger, Michael Pommerer, Tom Frei
In the past years Eberspaecher has installed Active Exhaust Silencers on several passenger vehicles with different diesel and gasoline engines on a prototype level. Meanwhile, a substantial reduction of the exhaust noise is regularly achieved in a broad frequency range covering all relevant engine orders. Due to the higher acoustic excitation and higher exhaust temperatures in gasoline engines it is more difficult to implement the ANC-technology on those engines. However, results from roller test benches focus on the acoustic performance as well as weight and volume reductions and demonstrate a marked improvement which was achieved with gasoline engines too. Further progress was made in the development of the durability and industrialization of all relevant components of the system. Finally, current design trends and possible fields of application will be discussed.
2011-05-17
Journal Article
2011-01-1635
Mingfeng Li, Jie Duan, Teik Lim
Gears are essential parts of many precision power and torque transmitting machines. However, the radiated intensive tonal noise due to the gear meshing is highly undesirable and annoying. In very severe cases, the gear vibrations can reduce the life and performance of the power transmitting components. Typical gearbox vibration and sound spectra contain several dominant narrowband tonal signals that are mixed in with a lower level broadband response signals. Hence, the control of mesh response of gearbox housing belongs to the problem of the rejection or cancellation of periodical disturbance. The frequencies of these tonal signals are related to the number of teeth and rotation speed, and highly predictable. Thus, a feedforward control system was normally adopted. In most of existed applications, an accurate reference based on the frequency information of tachometer pulse train signal is required for this kind of control system.
2011-05-17
Technical Paper
2011-01-1636
Chiharu Togashi PhD, Mitsuo Nakano PhD, Masao Nagai PhD
A lot of countermeasures have been developed in order to reduce interior noise. For example, improvements of rubber mount characteristics and other measures have been implemented. Recently electromagnetic active engine mounts based on a hydraulic engine mount have been developed. They are significantly effective for the reduction of the booming noise which is unpleasant for passengers. Although the LMS algorithm has been generally used for the active control, it has been used only for reducing booming noise. The authors developed a new control method in order to reduce not only the booming noise but also the noise and the vibration over wide frequency band for comfortable vehicle interior space. The authors studied the method which determines the feedback gain according to various conditions by modifying LMS algorithm. In this modified LMS algorithm, only an error signal was used as an input signal.
2011-05-17
Technical Paper
2011-01-1565
Jennifer Durfy, Sang-Bum Hong, Bibhu Mahanta
As fuel prices continue to be unstable the drive towards more fuel efficient powertrains is increasing. For engine original equipment manufacturers (OEMs) this means engine downsizing coupled with alternative forms of power to create hybrid systems. Understanding the effect of engine downsizing on vehicle interior NVH is critical in the development of such systems. The objective of this work was to develop a vehicle model that could be used with analytical engine mount force data to predict the vehicle interior noise and vibration response. The approach used was based on the assumption that the largest contributor to interior noise and vibration below 200 Hz is dominated by engine mount forces. An experimental transfer path analysis on a Dodge Ram 2500 equipped with a Cummins ISB 6.7L engine was used to create the vehicle model. The vehicle model consisted of the engine mount forces and vehicle paths that define the interior noise and vibration.
2011-05-17
Technical Paper
2011-01-1564
Tony Karlsson, Ragnar Glav
Simulation using basic acoustic 2-port elements is a time effective method for prediction of the attenuation of single components as well as of complete exhaust aftertreatment and silencer systems. However, with the complexity of current systems, the transformation from design geometries to networks of basic elements is not straightforward. In this paper a practical example of the modelling of a modern exhaust aftertreatment system is presented. A silencer aimed at the Euro 6 heavy duty emissions legislation containing complex flow turnings, parallel branches, DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) catalysts was modelled. Evaluation against measurements in order to understand the influence of the different acoustic elements upon overall attenuation and to improve the model with respect to near field and higher order mode effects was done.
2011-05-17
Technical Paper
2011-01-1563
Ki-Hwa Lee, Chung-Guen Nam, Hyung-Shin KIm, Dong-Kyu Yoo, Koo-Tae Kang
A comprehensive investigation was carried out in order to develop the idle sound quality for diesel V6 engine when the engine development process is applied to power-train system, which included new 8-speed automatic transmission for breaking down the noise contribution between the mechanical excitation and the combustion excitation. First of all, the improvement of dynamic characteristic can be achieved during the early stages of the engine development process using experimental modal analysis (EMA) & the robust design of each engine functional system. In addition, the engine structural attenuation (SA) is enhanced such that the radiated combustion noise of the engine can be maintained at a target level even with an increased combustion excitation. It was found that the engine system has better parts and worse parts in frequency range throughout the SA analysis. It is important that weak points in the system should be optimized.
2011-05-17
Journal Article
2011-01-1562
Tamer Elnady, Sara Elsaadany, D. W. Herrin
Diesel engines produce harmful exhaust emissions and high exhaust noise levels. One way of mitigating both exhaust emissions and noise is via the use of after treatment devices such as Catalytic Converters (CC), Selective Catalytic Reducers (SCR), Diesel Oxidation Catalysts (DOC), and Diesel Particulate Filters (DPF). The objective of this investigation is to characterize and simulate the acoustic performance of different types of filters so that maximum benefit can be achieved. A number of after treatment device configurations for trucks were selected and measured. A measurement campaign was conducted to characterize the two-port transfer matrix of these devices. The simulation was performed using the two-port theory where the two-port models are limited to the plane wave range in the filter cavity.
2011-05-17
Technical Paper
2011-01-1566
Thomas Reinhart, Mitchel Smolik
Several new or significantly upgraded heavy duty truck engines are being introduced in the North American market. One important aspect of these new or revised engines is their noise characteristics. This paper describes the noise related characteristics of the new DD15 engine, and compares them to other competitive heavy truck engines. DD15 engine features relevant to noise include a rear gear train, isolated oil pan and valve cover, and an amplified high pressure common rail fuel system. The transition between non-amplified and amplified common rail operation is shown to have a significant noise impact, not unlike the transition between pilot injection and single shot injection in some other engines.
2011-05-17
Technical Paper
2011-01-1583
Naga Narayana
Increasing sound quality with advanced audio technology has raised the bar for perceived quality targets for minimal interior noise and maximal speaker sound quality in a passenger vehicle. Speaker-borne structural vibrations and the associated squeak and rattle have been among the most frequent concerns in the perceived audio quality degradation in a vehicle. Digital detection of squeak and rattle issues due to the speaker-borne structural vibrations during the digital vehicle development phase has been a challenge due to the physical complexity involved. Recently, an effective finite element method has been developed to address structure-borne noise [1] and has been applied for detecting the issues of squeak and rattle in passenger vehicles due to vehicle-borne vibrations at vehicle, component and subcomponent levels [2, 3, 4, 5, 6, 7, 8].
2011-05-17
Technical Paper
2011-01-1586
Malika Perera, Stephanos Theodossiades, Homer Rahnejat, Patrick Kelly
Modern automotive industry is driven by improved fuel efficiency, whilst simultaneously increasing output power and reducing size/weight of vehicle components. This trend has the drawback of inducing various Noise, Vibration and Harshness (NVH) concerns in the drivetrain, since fairly low energy excitation often suffices to excite natural modes of thin walled structures, such as the transmission bell housing. Transmission rattle is one of the many undesired NVH issues, originating from irregularities in engine torque output. The crankshaft speed fluctuations are transferred through the transmission input shaft. Transmission compactness also allows repetitive interaction of conjugate loose gear pairs. The engine fluctuations disturb the otherwise unintended, but orderly meshing of these loose gears. This often leads to radiation of a characteristic air-borne noise from the impact sites.
2011-05-17
Technical Paper
2011-01-1591
Kumbhar S. Mansinh, Atul Miskin, Vishal Vasantrao Chaudhari, Ashish Rajput
The noise and vibration performance of diesel fueled automotives is critical for overall customer comfort. The stationary vehicle with engine running idle (Vehicle Idle) is a very common operating condition in city driving cycle. Hence it is most common comfort assessment criteria for diesel vehicles. Simulations and optimization of it in an early stage of product development cycle is priority for all OEMs. In vehicle idle condition, powertrain is the only major source of Noise and Vibrations. The key to First Time Right Idle NVH simulations and optimization remains being able to optimize all Transfer paths, from powertrain mounts to Driver Ear. This Paper talks about the approach established for simulations and optimization of powertrain forces entering in to frame by optimizing powertrain mount hard points and stiffness. Powertrain forces optimized through set process are further used to predict the vehicle passenger compartment noise and steering vibrations.
2011-05-17
Technical Paper
2011-01-1604
Zhi-yong Chen, Guang-ming Wu, Wen-ku Shi, Qing-guo Wang, Teng Teng
Hyperelastic model constants of rubber material are predicted based on test date. The fluid-structure interaction model of light vehicle cab's hydraulic mount is established. Static characteristics of the hydraulic mount are analyzed by quasi-static method. In dynamic characteristics analysis, the flow model of fluid is set to turbulent K-Epsilon RNG. The dynamic stiffness and loss angle of the hydraulic mount are presented via the finite element model. The simulations of static and dynamic characteristics agree well with corresponding test results. The effects of main structure parameters to the dynamic characteristics of the hydraulic mount are analyzed based on the finite element model.
2011-05-17
Technical Paper
2011-01-1601
Abolfazl Eskandari, Mostafa haghroosta, Kia Valefi
One of the most important factors that must be taken into account during vehicle design is the quality of noise and vibration produced by the vehicle. This is evident from manufacturer's attempt to produce quieter product. On the other hand, some of the vehicles have not good NVH properties and must be modified in order to be successful in the market. In this type of vehicles, no basic changes can be made, and focus must be on restricted improvements. In this research, a vehicle of this kind is selected and measures have been taken to improve its noise and vibration behavior. By implementing suspension techniques, some of the vibration characteristics of drive train and its influence on the interior noise at different engine speeds and under road load have been investigated. In addition, the effect of double layer instead of single layer muffler skin on the cabin noise has been probed.
2011-05-17
Journal Article
2011-01-1602
Christopher Hartley
Understanding the resonant behavior of vehicle closures such as doors, hoods, trunks, and rear lift gates can be critical to achieve structure-borne noise, vibration, and harshness (NVH) performance requirements, particularly below 100Hz. Nearly all closure systems have elastomer weatherstrip components that create a viscoelastic boundary condition along a continuous line around its perimeter and is capable of influencing the resonant behavior of the closure system. This paper outlines an approach to simulate the static and dynamic characteristics of a closed-cell Ethylene Propylene Diene Monomer (EPDM) foam rubber weatherstrip component that is first subjected to a large-strain quasi-static preload with a small-strain sinusoidal dynamic load superimposed. An outline of a theoretical approach using “phi-functions” as developed by K.N. Morman Jr., and J.C.
2011-05-17
Technical Paper
2011-01-1528
Deepak Rana, Felix Regin, Mohan Makana
A muffler or silencer is an integral part of the exhaust system and is a device used to prevent sound from reaching the openings of the exhaust duct and radiating as far field noise. Different acoustical design and analysis techniques are used to predict the acoustical performance of exhaust systems. Flow noise from exhaust tail pipe is one of the major noise sources in a vehicle. Flow noise is generated mainly during fast acceleration operating condition due to complex flow behavior. In this paper, we have studied the detailed flow field and tried to establish an analyses procedure for flow noise prediction. The flow analysis is carried out in commercial CFD solver Star CCM+. The transient engine boundary conditions are obtained from the experimental testing. The flow noise generated from the muffler was calculated by acoustic analogy of Lighthill using the above boundary conditions.
2011-05-17
Journal Article
2011-01-1527
Rick Dehner, Ahmet Selamet, Philip Keller, Michael Becker
The unsteady surge behavior of a turbocharger compression system is studied computationally by employing a one-dimensional engine simulation code. The system modeled represents a new turbocharger test stand consisting of a compressor inlet duct breathing from ambient, a centrifugal compressor, an exit duct connected to an adjustable-volume plenum, followed by another duct which incorporates a control valve and an orifice flow meter before exhausting to ambient. Characteristics of mild and deep surge are captured as the mass flow rate is reduced below the stability limit, including discrete sound peaks at low frequencies along with their amplitudes in the compressor (downstream) duct and plenum. The predictions are then compared with the experimental results obtained from the cold stand placed in a hemi-anechoic room.
2011-05-17
Technical Paper
2011-01-1530
Uday Senapati, Graham Evans, Aaron Hankinson
The drive for lower CO₂ emissions places ever greater demand on cooling dissipation for a multi-cylinder internal combustion engine. This challenge has increased the requirements of the engine cooling system, particularly in countries where high ambient temperatures prevail and HVAC usage is high. Environmental necessity coupled with market demands have resulted in cars which emit a higher level of cooling fan noise which is intrusive in an urban environment and objectionable to customers. Conventional quantification of noise using traditional units and metrics was found to be insufficient for effective Sound Quality analysis. To assist Bentley Motors, a high performance luxury vehicle manufacturer, with its brand cachet and its commitment to the environment and customer, a new sound metric analysis has been devised to help the business deliver an ever-quieter exterior power unit cooling system.
2011-05-17
Journal Article
2011-01-1529
Zhenlin Ji, Zhi Fang
The one-dimensional analytical approach, three-dimensional finite element method (FEM) and boundary element method (BEM) are developed to predict and analyze the acoustic attenuation performance of three-pass perforated tube muffler with end-resonator. For an elliptical muffler, the predictions of transmission loss from the FEM and BEM agree well each other throughout the frequency range of interest, while the one-dimensional analytical solution shows a reasonable agreement with the numerical predictions at lower frequencies and deviates at higher frequencies. The FEM is then used to investigate the effects of geometrical parameters and internal structure on the acoustic attenuation performance of three-pass perforated tube muffler with end-resonator.
2011-05-17
Technical Paper
2011-01-1532
Charlie Teng, Fumin Pan, Jemai Missaoui, Scott Deraad
Turbocharged gasoline engines are typically equipped with a compressor anti-surge valve or CBV (compressor by-pass valve). The purpose of this valve is to release pressurized air between the throttle and the compressor outlet during tip-out maneuvers. At normal operating conditions, the CBV is closed. There are two major CBV mounting configurations. One is to mount the CBV on the AIS system. The other is to mount the CBV directly on the compressor housing, which is called an integrated CBV. For an integrated CBV, at normal operating conditions, it is closed and the enclosed passageway between high pressure side and low pressure side forms a “side-branch” in the compressor inlet side (Figure 12). The cavity modes associated with this “side-branch” could be excited by shear layer flow and result in narrow band flow noises.
2011-05-17
Technical Paper
2011-01-1533
Nicholas Earnhart, Kenneth Marek, Kenneth Cunefare
Hydraulic systems pose a particular problem for noise control. Due to the high speed of sound in hydraulic fluids, components typically designed to reduce fluid-borne noise can easily exceed practical size constraints. This paper presents novel solutions to creating compact and effective noise control devices for fluid power systems. A hydraulic silencer is presented that utilizes a voided polymer lining in lieu of a pressurized bladder. Theoretical modeling is developed which predicts device performance and can assist in future design work. Experimental results are presented to demonstrate the performance of the device. Both voided and non-voided liners are tested to show the effect of the voiding on the performance. In addition, theoretical modeling and experimental results are presented for a prototype Helmholtz resonator that is two orders of magnitude smaller than previously developed devices.
2011-05-17
Technical Paper
2011-01-1536
Mohammad Kazem Baghi Abadi, Ali Hajnayeb, Ali Hosseingholizadeh, Ahmad Ghasemloonia
This paper presents an algorithm for the detection of single and multiple misfires in internal combustion engines, using only the signal of the knock sensor. Several experiments were conducted on a four-cylinder engine to obtain the necessary signals in the healthy and faulty conditions. The faulty conditions were created by disconnecting the wires of the spark-plugs. The signal of the knock sensor is analyzed and the time-domain signals of different orders of engine vibrations are extracted using a Vold-Kalman filter (VKF). A set of statistical features were then extracted from the time-domain signals of each order. These features are representative of the engine condition. In the next step, the computed features were plotted for different states and are analyzed. Consequently, a criterion for identifying the engine misfire is obtained based on the extracted features.
2011-05-17
Technical Paper
2011-01-1535
Christopher Edward Baker, Homer Rahnejat, Ramin Rahmani PhD, Stephanos Theodossiades
Piston compression rings are thin, incomplete circular structures which are subject to complex motions during a typical 4-stroke internal combustion engine cycle. Ring dynamics comprises its inertial motion relative to the piston, within the confine of its seating groove. There are also elastodynamic modes, such as the ring in-plane motions. A number of modes can be excited, dependent on the net applied force. The latter includes the ring tension and cylinder pressure loading, both of which act outwards on the ring and conform it to the cylinder bore. There is also the radial inward force as the result of ring-bore conjunctional pressure (i.e. contact force). Under transient conditions, the inward and outward forces do not equilibrate, resulting in the small inertial radial motion of the ring.
2011-05-17
Journal Article
2011-01-1540
Darrell Robinette, Michael Grimmer, Randall Beikmann
The objective of this investigation is to characterize the torsional characteristics of the hydrodynamic torque converter. Analytical and experimental techniques are used to quantify the relationship between torsional oscillations imposed on the pump to those at the turbine as a function of frequency, operating point and design. A detailed model of the hydrodynamic torque converter based upon one-dimensional flow theory is used to establish fundamental torsional behavior independent of the downstream mechanical system. A simplified linear spring-mass-damper representation of the hydrodynamic torque converter is derived whose coefficients are proportional to pump speed for a particular design. A transmission dynamometer test cell with the capability to produce torsional oscillations was used to develop frequency response functions for various torque converters in a transmission, operating at steady state conditions.
2011-05-17
Technical Paper
2011-01-1544
Vittorio Ravaglioli, Fabrizio Ponti, Federico Stola
This paper presents the results of several studies, performed on different powertrain configurations, aimed at analyzing the correlations existing between torque and speed frequency components in an internal combustion engine. Engine speed fluctuations depend in fact on torque delivered by each cylinder, therefore it is easy to understand how these two quantities are directly connected. The presented methodology allows identifying a dynamic model, expressed as a transfer function that depends only on the structure of the engine-driveline system. The identified model can be used to obtain information about torque delivered by the engine and combustion positioning within the engine cycle starting from engine speed measurement. The speed signal is picked up directly from the sensor facing the toothed wheel that is already mounted on the engine for control purposes.
Viewing 1 to 30 of 61087

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