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Viewing 1 to 30 of 3874
2017-09-04
Technical Paper
2017-24-0024
Andrea Piano, Federico Millo, Davide Di Nunno, Alessandro Gallone
The need for achieving a fast warm up of the exhaust system has raised in the recent years a growing interest in the adoption of Variable Valve Actuation (VVA) technology for automotive diesel engines. As a matter of fact, different measures can be adopted through VVA to accelerate the warm-up of the exhaust system, such as using hot internal Exhaust Gas Recirculation (iEGR) to heat the intake charge, especially at part load, or adopting early Exhaust Valve Opening (eEVO) timing during the expansion stroke, so to increase the exhaust gas temperature during blowdown. In this paper a simulation study is presented evaluating the impact of VVA on the exhaust temperature of a modern light duty 4-cylinder diesel engine, 1.6 liters, equipped with a Variable Geometry Turbine (VGT).
2017-09-04
Technical Paper
2017-24-0167
Enrico Mattarelli, Carlo Rinaldini, Tommaso Savioli, Giuseppe Cantore, Alok Warey, Michael Potter, Venkatesh Gopalakrishnan, Sandro Balestrino
A CFD study on a 2-stroke (2-S) opposed piston high speed direct injection (HSDI) Diesel engine is reported in this work. The engine main features (bore, stroke, port timings, et cetera) were defined in a previous stage of the project, with the support of CFD-1D engine simulations and empirical hypotheses. The current analysis is focused on the assembly made up of scavenge ports, manifold and cylinder. The first step of the study consisted in the construction of a parametric mesh on a simplified geometry. Two geometric parameters and 3 different operating conditions were considered. A CFD-3D simulation by using a customized version of the KIVA-4 code was performed on a set of 243 different cases, sweeping all the most interesting combinations of geometric parameters and operating conditions. The post-processing of this huge amount of data allowed us to define the most effective geometric configuration, named baseline.
2017-09-04
Technical Paper
2017-24-0146
Vincent Raimbault, Jerome Migaud, David Chalet, Michael Bargende, Emmanuel Revol, Quentin Montaigne
Upcoming regulations and new technologies are challenging the internal combustion engine and increase the pressure on car manufacturers to further reduce powertrain emissions. Indeed, RDE pushes engineering to keep low emissions not only at the bottom left of the engine map but in the complete range of load and engine speeds. This means for gasoline engines that the strategy used to increase the low end torque and power while moving out of lambda one conditions is no longer sustainable. For instance scavenging, which helps to increase the enthalpy at the turbine at low engine speed cannot be applied and thus leads to a reduction in low-end torque. Similarly, enrichment to keep the exhaust temperature sustainable in the exhaust tract components cannot be applied any more. The proposed study aims to provide a solution to keep the low end torque while maintaining lambda at 1. The tuning of the air intake system helps to improve the volumetric efficiency using resonance charging effects.
2017-09-04
Technical Paper
2017-24-0144
Carlo Beatrice, Maria Antonietta Costagliola, Chiara Guido, Pierpaolo Napolitano, Maria Vittoria Prati
Diesel particulate filter (DPF) is the most effective emission control device for reducing particle emissions (both in mass, PM, and number, PN) from diesel engines, however many studies have reported elevated emissions of nanoparticles (<50 nm) during its regeneration. In this paper the results of an extensive literature search are presented (about 150 reports and scientific papers). During DPF active regeneration most of the literature studies show an increase in the number of the emitted nanoparticles of about 2-3 orders of magnitude compared to the normal operating conditions. Many factors can influence their amount, size distribution, chemical-physical nature (volatiles, semi-volatiles, solid) and the duration of the regenerative event: i.e. DPF load and thermodynamic conditions, lube and fuel sulfur content, engine operative conditions, PN sampling and measurement methodologies.
2017-09-04
Technical Paper
2017-24-0139
Francesco Barba, Alberto Vassallo, Vincenzo Greco
The aim of the present study is to improve the effectiveness of the engine and aftertreatment calibration process through the critical evaluation of several methodologies available to estimate the soot mass flow produced by diesel engines and filtered by Diesel Particulate Filters (DPF). In particular, the focus of the present study has been the development of a reliable simulation method for the accurate prediction of the engine-out soot mass flow starting from Filter Smoke Number (FSN) measurements executed in steady state conditions, in order to predict the DPF loading considering different engine working conditions corresponding to NEDC and WLTP cycles. In order to achieve this goal, the study was split into two parts: - Correlation between ‘wet soot’ (measured by soot filter weighing) and the ‘dry soot’ (measured by the Micro Soot Sensor MSS).
2017-09-04
Technical Paper
2017-24-0135
Shuxia Miao, Lin Luo, Yan Liu, Zhangsong Zhan
New emissions regulations of light-duty vehicles (China 6) will be implemented in China from July 1, 2020. This standard includes two stages, China 6a and China 6b, in which the PM limits of 4.5 mg/km and 3.0 mg/km are introduced respectively, the PN limit is set to be 6×10e11 #/km for both stages. The WLTC testing cycle will be implemented in China 6 regulation as well. In this study a light-duty vehicle satisfying China 6(b) emission standards was developed by improving the engine raw emissions, optimizing the calibration and adding a coated GPF to the after-treatment system. The impacts of ash content and consumption of engine oil and the fast ash accumulation to vehicle emissions and backpressure were analyzed through dynamometer testing. The vehicle after-treatment system was then designed and developed to meet China 6(b) emission standards. The characteristics of soot accumulated through mimicking routine driving under cold environments were tested.
2017-09-04
Technical Paper
2017-24-0128
Lauretta Rubino, Jan Piotr Oles, Antonino La Rocca
Environmental authorities such as EPA, VCA have enforced stringent emissions legislation governing air pollutants released into the atmosphere. Of particular interest is the challenges introduced by the limit on particulate number (PN) counting (#/km) and real driving emissions (RDE) testing; with the Euro 6c emissions legislation being shortly introduced for the gasoline direct injection engines. Gasoline particulate filters (GPF) are considered to be the most immediate solution. While engine calibration and testing over the NEDC allows the limits to be met, real driving emission and cold start represent a challenge. The present work focuses on an experimental durability study on road under real word driving conditions. Two set of experiments were carried out. The first study analyzed a Gasoline Particulate Filter (GPF) (2,4 liter, diameter 5,2” round) installed in underfloor (UF) position driven for up to 200.000 km.
2017-09-04
Technical Paper
2017-24-0127
Lauretta Rubino, Dominic Thier, Torsten Schumann, Stefan Guettler, Gerald Russ
With the increasing number of engines utilizing direct fuel injection and the upcoming more stringent emission legislation, regulating not only particulate mass (PM) but particulate number (PN), emissions of Direct Injection Spark Ignition Engines (DISI) are becoming of increasing concern. Gasoline Particle Filters (GPF) represent a novel potential measure to reduce particle number emissions from DISI engines and are particularly effective in view of the tight particle number limits requirements at cold start and over RDE. Even if some learning from the development and application of particulate filters to diesel engines can be transferred to gasoline engines, the particulate consistence, the mass to number ratio and the temperature as well as the gas composition of gasoline engines are significant different to diesel engines. Therefore, there is the need to study the application of particulate filters to gasoline engines carefully.
2017-09-04
Technical Paper
2017-24-0126
Christian Zöllner, Dieter Brueggemann
The removal of particulate matter (PM) from diesel exhaust is necessary to protect the environment and human health. To meet the strict emission standards for diesel engines an additional exhaust aftertreatment system is essential. Diesel particulate filters (DPF) are established devices to remove emitted PM from diesel exhaust. But the deposition and the accumulation of soot in the DPF influences the filter back pressure and therefore the engine performance and the fuel consumption which is why a periodical regeneration through PM oxidation is necessary. The oxidation behavior should result in an effective regeneration mode that minimizes the fuel penalty and limits the temperature rise while maintaining a high regeneration efficiency. Excessive and fast regenerations have to be avoided as well as uncontrolled oxidations leading to damages of the filter and fuel penalty.
2017-09-04
Technical Paper
2017-24-0124
Michael Maurer, Peter Holler, Stefan Zarl, Thomas Fortner, Helmut Eichlseder
To fulfil the new European real driving emissions (RDE) legislation, the LNT operation strategy – especially for DeNOx events – has to be optimized to minimize NOx as well as CO and HC emissions. On one hand the DeNOx purges should be long enough to fully regenerate the lean NOx trap, on the other hand the purges should be as short as possible to reduce the fuel consumption penalty from rich mode. Fundamental experiments have been conducted on a synthetic-gas-test-bench, purposely designed to test LNT catalysts. This methodology allowed to remove NOx from the gasfeed after the lean storage phase. The actually reduced amount of NOx could be easily calculated from the NOx storage before a regeneration minus the NOx that was desorbed during the DeNOx event and afterwards thermally desorbed NOx. To show the effect of aging method on the regeneration characteristics, tests have been performed with a in a car endurance run aged LNT and a synthetic hydrothermally aged LNT.
2017-09-04
Technical Paper
2017-24-0109
Nic Van Vuuren, Lucio Postrioti, Gabriele Brizi, Federico Picchiotti
ABSTRACT: Selective Catalytic Reduction (SCR) diesel exhaust aftertreatment systems are virtually indispensable to meet NOx emissions limits worldwide. These systems generate the NH3 reductant by injecting aqueous urea solution (AUS-32/AdBlue®/DEF) into the exhaust for the SCR NOx reduction reactions. Understanding the AUS-32 injector spray performance is critical to proper optimization of the SCR system. Specifically, better knowledge is required of urea sprays under operating conditions including those where fluid temperatures exceed the atmospheric fluid boiling point. Results were previously presented from imaging of an AUS-32 injector spray which showed substantial structural differences in the spray between room temperature fluid conditions, and conditions where the fluid temperature approached and exceeded 104º C and “flash boiling” of the fluid was initiated.
2017-09-04
Technical Paper
2017-24-0121
Ivan Arsie, Giuseppe Cialeo, Federica D'Aniello, Cesare Pianese, Matteo De Cesare, Luigi Paiano
The demand for high NOx conversion efficiency and low tailpipe ammonia slip for urea-based selective catalytic reduction (SCR) systems has substantially increased in the past decade, as NOx emission legislations for Diesel engines are becoming more stringent than ever before. Model-based control strategies are fundamental to meet the dual objective of maximizing NOx reduction and minimizing NH3 slip in urea-SCR catalysts. In this paper, a control oriented model of a Cu-zeolite urea-selective catalytic reduction (SCR) system for automotive diesel engines is presented. The model is derived from a quasi-dimensional four-state model of the urea-SCR plant. In order to make it suitable for the real-time urea-SCR management, a reduced order one-state model has been developed, with the aim of capturing the essential behavior of the system with a low computational demand. The model estimates the relevant species (i.e. NO, NO2 and NH3) independently.
2017-09-04
Technical Paper
2017-24-0123
Christopher Eck, Futoshi Nakano
Small commercial vehicles (SCV) with Diesel engines require efficient exhaust aftertreatment systems to reduce the emissions while keeping the fuel consumption and total operating cost as low as possible. To meet current emission legislations in all cases, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) and some NOx treatment device (e.g. a lean NOx trap or selective catalytic reduction, SCR) are required. Creating a cost-effective SCV also requires to keep the cost for the aftertreatment system as low as possible because the contribution to total vehicle cost is high. By using more sophisticated and more robust operating strategies and control algorithms, the hardware cost can be reduced. To keep the calibration effort at a low level, it is necessary to apply only algorithms which have a time-efficient calibration procedure. This paper will focus on the active regeneration of the DPF.
2017-09-04
Technical Paper
2017-24-0096
Laura Sophie Baumgartner, Stephan Karmann, Fabian Backes, Andreas Stadler, Georg Wachtmeister
Due to its molecular structure, methane provides several advantages as fuel for internal combustion engines. First, owing to the single carbon atom per molecule, a formation of particular matter becomes drastically more unlikely and second the carbon to hydrogen ratio of methane reduces the amount of carbon dioxide by 20 % at the same energy output. To cope with nitrogen oxide emissions a high level of excess air is beneficial, which on the other hand deteriorates the flammability and combustion duration of the mixture. One approach to meet these challenges and ensure a stable combustion process are fuel scavenged prechambers. The flow and combustion processes within these prechambers are highly influenced by the position, orientation, number and overall cross-sectional area of the orifices connecting the prechamber and the main combustion chamber.
2017-07-10
Technical Paper
2017-28-1935
Praveen V V, P Baskara Sethupathi
Abstract Formula SAE is a prestigious engineering design competition, where student team design, fabricate and test their formula style race car, with the guidelines of the FSAE rulebook, according to which the car is designed, for example the engine must be a four-stroke, Otto-cycle piston engine with a displacement no greater than 710cc. According to FSAE 2017 Rule Book [1], ARTICLE 3, IC3.2 and IC3.3 state that the maximum sound level should not exceed 110 dBC at an average piston speed of 15:25 m/s (for the KTM 390 engine, which has 60 mm stroke length, the noise level will be measured at 7500 RPM) and 103 dBC at Idle RPM. So, the active muffler which works as a normal reflective muffler till the 7500 RPM range, after which an electronic controlled throttle mechanism is used to reduce the backpressure (since after 7500 RPM the noise level doesn't matter in FSAE) by using tach signal from the engine to control the throttle (two position).
2017-07-10
Technical Paper
2017-28-1927
Saurav Roy, Jyotirmoy Barman, Rizwan Khan
Abstract The urea NOx selective catalytic reduction (SCR) is an effective technique for the reduction of NOx emitted from diesel engines. Urea spray quality has significant effect on NOx conversion efficiency. Air less injection is one of effective, less complex way of injecting urea spray into the Exhaust stream. Further with air less injection it become more challenging in an engine platform of ~3 to 4L where Exhaust mass flow and temperature are relatively less. The droplet diameter and velocity distribution of De-Nox system has taken as input along with Engine raw emission data for a numerical model. The atomization and evaporation of airless urea injection systems were modeled using computational fluid dynamics. The numerical model was validated by the experimental results.
2017-07-10
Technical Paper
2017-28-1942
Rajvardhan Nalawade
Abstract The exhaust system of a vehicle is an integral part as it is responsible for reducing the noise of the exhaust gases and controlling the emissions as well. Mufflers are particularly the sub part of an exhaust system that reduce the sound level. Their geometry and size are meticulously calculated and decided so as to increase destructive interference of sound waves and their absorption by sound absorbent material packed around it. There are five types of basic mufflers which will be compared for their transmission losses. For this analysis of transmission losses, a software called Ricardo Wave Build has been used. Transmission loss is basically, the difference between the energy of the incoming charge and the energy of the outgoing charge of gases. So, more is the transmission loss, more efficient and productive is the muffler. Based upon the transmission loss characteristics, the mufflers are paired with their corresponding applications.
2017-07-10
Technical Paper
2017-28-1945
Jyotirmoy Barman, Himanshu Gambhir, Rizwan Khan
Abstract During the last few decades, concerns have grown on the negative effects that diesel particulate matter has on health. Because of this, particulate emissions were subjected to restrictions and various emission-reduction technologies were developed. It is ironic that some of these technologies led to reductions in the legislated total particulate mass while neglecting the number of particles. Focusing on the mass is not necessarily correct, because it might well be that not the mass but the number of particles and the characteristics of them (size, composition) have a higher impact on health. During the diesel engine combustion process, soot particles are produced which is very harmful for the atmosphere. Particulate matter is composed of much organic and inorganic composition which was analyzed after the optimization of SCR and EGR engine out.
2017-06-17
Journal Article
2017-01-9550
David Neihguk, M. L. Munjal, Arvind Ram, Abhinav Prasad
Abstract A production muffler of a 2.2 liter compression ignition engine is analyzed using plane wave (Transfer Matrix) method. The objective is to show the usefulness of plane wave models to analyze the acoustic performance (Transmission Loss, TL) of a compact hybrid muffler (made up of reactive and dissipative elements). The muffler consists of three chambers, two of which are acoustically short in the axial direction. The chambers are separated by an impervious baffle on the upstream side and a perforated plate on the downstream side. The first chamber is a Concentric Tube Resonator (CTR). The second chamber consists of an extended inlet and a flow reversal 180-degree curved outlet duct. The acoustic cavity in the third chamber is coupled with the second chamber through the acoustic impedances of the end plate and the perforated plate.
2017-06-05
Technical Paper
2017-01-1791
David Neihguk, Shreyas Fulkar
Abstract Parametric model of a production hybrid (made up of reactive and dissipative elements) muffler for tractor engine is developed to compute the acoustic Transmission Loss (TL). The objective is to simplify complex muffler acoustic simulations without any loss of accuracy, robustness and usability so that it is accessible to all product development engineers and designers. The parametric model is a 3D Finite Element Method (FEM) based built in COMSOL model builder which is then converted into a user-friendly application (App) using COMSOL App builder. The uniqueness of the App lies in its ability to handle not only wide range of parametric variations but also variations in the physics and boundary conditions. This enables designers to explore various design options in the early design phase without the need to have deep expertise in a specific simulation tool nor in numerical acoustic modeling.
2017-06-05
Technical Paper
2017-01-1789
Rafael Veloso, Robert Fairbrother, Yasser Elnemr
Abstract The acoustics of automotive intake and exhaust systems is typically modeled using linear acoustics or gas-dynamics simulation. These approaches are preferred during basic sound design in the early development stages due to their computational efficiency compared to complex 3D CFD and FEM solutions. The linear acoustic method reduces the component being modelled to an equivalent acoustic two-port transfer matrix which describes the acoustic characteristic of the muffler. Recently this method was used to create more detailed and more accurate models based on a network of 3D cells. As the typical automotive muffler includes perforated elements and sound absorptive material, this paper demonstrates the extension of the 3D linear acoustic network description of a muffler to include the aforementioned elements. The proposed method was then validated against experimental results from muffler systems with perforated elements and sound absorptive material.
2017-06-05
Technical Paper
2017-01-1795
Ahmad Abosrea, Tamer Elnady
Abstract Flow-generated noise has recently received a lot of attention within the process of designing exhaust and intake systems. Flow-generated noise can limit the amount of sound reduction a muffler can introduce inside ducts. This is more important in the modern system design where mufflers are compact and the flow speeds become higher in different sections inside the muffler. In this paper, three measurement techniques are used to measure the flow-generated noise from a duct element. The first is based on calculating the sound power levels inside a reverberation room according to ISO 3741. The radiated noise is measured from the muffler body as a source of noise, then from the tail pipe as an active one-port source. The second is based on sound power measurements inside the ducts using the active two-port theory. The third is measuring the sound pressure radiation inside an anechoic room.
2017-06-05
Technical Paper
2017-01-1793
William Seldon, Amer Shoeb, Daniel Schimmel, Jared Cromas
Abstract As regulations become increasingly stringent and customer expectations of vehicle refinement increase, the accurate control and prediction of exhaust system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace. The goal of this project was to improve the predicative accuracy of the GT-power engine and exhaust model and to update internal best practices for modeling. This paper will explore the details of an exhaust focused correlation project that was performed on a naturally aspirated spark ignition eight-cylinder engine. This paper and SAE paper “Experimental GT-POWER Correlation Techniques and Best Practices Low Frequency Acoustic Modeling of the Intake System of a Turbocharged Engine” share similar abstracts and introductions; however, they were split for readability and to keep the focus on a single a single subsystem.
2017-06-05
Technical Paper
2017-01-1798
Jiri Navratil, Warren Seeley, Peng Wang, Shriram Siravara
Abstract The ability to accurately predict exhaust system acoustics, including transmission loss (TL) and tailpipe noise, based on CAD geometry has long been a requirement of most OEM’s and Tier 1 exhaust suppliers. Correlation to measurement data has been problematic under various operating conditions, including flow. This study was undertaken to develop robust modelling technique, ensuring sensible correlation between the 1-D models and test data. Ford use Ricardo WAVE as one of their 1-D NVH tools, which was chosen for the purpose of this benchmark study. The most commonly used metrics for evaluating the acoustical performance of mufflers are insertion loss (IL), TL, and noise reduction (NR). TL is often the first step of analysis, since it represents the inherent capability of the muffler to attenuate sound if both the source and termination are assumed to be anechoic. It can also be reliably measured and numerically simulated without having to connect to an engine.
2017-06-05
Journal Article
2017-01-1797
Adrien Mann, Raj Nair, Jaspreet Singh Gill, Brett Birschbach, Patrick Crowley
Abstract Exhaust systems including mufflers are commonly mounted on engines to reduce the firing cycle noise originating from the combustion process. However, mufflers also produce flow-induced self-noise, originating from the complex flow path throughout the muffler. As an engine prototype is not available in the early stages of a development program, it is challenging to assess the acoustic performance of the full system when only experiment is available. It is also difficult to pinpoint the design features of a muffler generating noise, as a portion of the noise is generated internally. Numerical approaches are a possible alternative. However, capturing non-linear dissipation mechanisms and thermal fluctuations of exhaust flows is challenging, while necessary to accurately predict flow noise.
2017-06-05
Technical Paper
2017-01-1753
Jack Hall Riddle, Ya-Juan Bemman, Tom Frei, Sihui Wu, Ishang Padalkar
Abstract Demands for engines to operate at low-frequency firing order are increasing in the automotive market. This requirement is driven by consumer and regulatory demand for vehicles which are more efficient in the use of fuel. As a result, engine and transmission technologies have been developed which permit operation of engines with fewer cylinders at increasingly low RPM’s. The resulting low frequency exhaust noise is more difficult to attenuate than in vehicles in years past. At the same time, vehicles often have less packaging space for mufflers, when larger volume would otherwise be needed to attenuate at lower frequencies. A further challenge is the demand for increasingly refined performance sounds from the exhaust systems of premium cars despite the technical obstacles involved in even maintaining sound quality. Finally, legally permissible sound levels are decreasing in some markets. These market and regulatory demands require new solutions.
2017-06-05
Technical Paper
2017-01-1782
Jobin Puthuparampil, Henry Pong, Pierre Sullivan
Abstract Large-scale emergency or off-grid power generation is typically achieved through diesel or natural gas generators. To meet governmental emission requirements, emission control systems (ECS) are required. In operation, effective control over the generator’s acoustic emission is also necessary, and can be accomplished within the ECS system. Plug flow mufflers are commonly used, as they provide a sufficient level of noise attenuation in a compact structure. The key design parameter is the transmission loss of the muffler, as this dictates the level of attenuation at a given frequency. This work implements an analytically decoupled solution, using multiple perforate impedance models, through the transfer matrix method (TMM) to predict the transmission loss based on the muffler geometry. An equivalent finite element model is implemented for numerical simulation. The analytical results and numerical results are then evaluated against experimental data from literature.
2017-06-05
Technical Paper
2017-01-1865
Peter Van der Linden, Frank Daenen, Masashi Komada, Hideto Ogawa
Abstract The tendency for car engines to reduce the cylinder number and increase the specific torque at low rpm has led to significantly higher levels of low frequency pulsation from the exhaust tailpipe. This is a challenge for exhaust system design, and equally for body design and vehicle integration. The low frequency panel noise contributions were identified using pressure transmissibility and operational sound pressure on the exterior. For this the body was divided into patches. For all patches the pressure transmissibility across the body panels into the interior was measured as well as the sound field over the entire surface of the vehicle body. The panel contributions, the pressure distribution and transmissibility distribution information were combined with acoustic modal analysis in the cabin, providing a better understanding of the airborne transfer.
2017-06-05
Technical Paper
2017-01-1875
Martino Pigozzi, Flavio Faccioli, Carlo Ubertino, Davide Allegro, Daniel Zeni
Abstract Within recent years, passenger comfort has become a main focus of the automotive industry. The topic is directly connected with acoustics, since sounds and noises have a major impact on the well-being of vehicle occupants. So-called “noise control” focuses on directly optimizing acoustic comfort by implementing innovative materials or geometries for automotive components and systems. One possibility to optimize the acoustics within a vehicle is connected to the phenomenon of sloshing in Selective Catalytic Reduction (SCR) tanks. Sloshing is a noise which is generated during normal driving situations by the motion of the Diesel Exhaust Fluid (DEF) in the tank. Until now, no procedure for measuring sloshing noise in SCR tanks has been defined, and neither a specific acoustic target which the SCR tanks need to fulfil.
2017-06-05
Technical Paper
2017-01-1827
Michael J. Santora, Cyril Gbenga Ige, Jeff Otto, David Egolf
Abstract A muffler attached to an engine attenuates sound over a dedicated frequency range. This research involves the development of an active muffler that is keyed to the revolutions per minute (rpm) of the engine and suppresses the fundamental frequency being exhausted through the tailpipe. The active muffler consists of a tracking side-branch resonator terminated with a composite piezoelectric transducer. The use of an exponential horn as a resonating cavity and terminated with a composite piezoelectric transducer is presented. This would create Electromechanical Active Helmholtz Resonator (EMAHR) creates a notch that can be moved between 200-1000 Hz. The use of acoustical-to-mechanical, mechanical-to-electrical, and analog-to-digital transformations to develop a system model for the active muffler are presented. These transforms will be presented as two-port network parameters. The use of two-port networks to model the electroacoustic system are a defining factor in the analysis.
Viewing 1 to 30 of 3874