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The problem associated with laboratory evaluation of muffler acoustical characteristics are complicated both by the acoustical considerations involved in obtaining an adequate noise source and by the ambiguities involved in defining what constitutes quality in a muffler built for general application. In order to quantitatively define the characteristics of quality mufflers, an extensive series of field tests were conducted on a variety of sizes and types of mufflers in conjunction with four engine configurations. Work then turned to the development of a wide band siren noise source and acoustical test system which would simulate the high impedance character of an engine exhaust noise source, and in addition generate the necessary intensity and spectral characteristics required to obtain test data over the range of noise conditions encountered in the field.

Geartrain noise can be a significant contribution to the overall sound level of diesel engines. Some engine manufacturers employ isolation solutions such as sound deadening covers and foam panels to combat the problem, but these add cost. Little has been published on geartrain noise reduction, and public standards for diesel geartrain design and development are not available. This paper describes an experimental study of the relative influence of gear design parameters on the rattle noise of a diesel engine timing geartrain. The geartrains of several diesel engines were benchmarked to determine the noise reduction strategies employed. A total of three gear sets were designed and tested in a 3.3L four cylinder normally aspirated diesel engine. The experimentation quantified the influence of an anti backlash idler gear in reducing gear rattle noise, and revealed that a key path for gear rattle noise transmission is through an idler gear journal bearing shaft.

A physics-based spark ignition model was developed and integrated into a commercial CFD code. The model predicted the spark discharge process based on the electrical parameters of the secondary ignition circuit, tracked the spark motion as it was stretched by in-cylinder gas motion, and determined the resulting energy deposition to the gas. In concert with the existing kinetic solver in the CFD code, the resulting ignition and flame propagation processes were simulated. The model results have been validated against both imaging rig experiments of the spark in moving air and against engine experimental data. The model was able to replicate the key features of the spark and to capture the cyclic variability of high-dilution combustion when multiple engine cycles were simulated.

The principles of the magnetic-perturbation method of flaw detection and the Barkhausen noise residual stress measurement method are briefly reviewed. It is suggested that they provide very powerful tools for assuring improved ball bearing performance. The methods are applied for the evaluation of ball bearing races. Typical experimental results are presented along with metallurgical sectioning correlation.

To aid in the catalytic converter design and development process, a test apparatus was designed and built which will allow comparative evaluation of the durability of candidate mat materials under highly controlled thermal and vibration environments. The apparatus directly controls relative shear deflection between the substrate and can to impose known levels of mat material strain while recording the transmitted shear force across the mat material. Substrate and can temperatures are controlled at constant levels using a resistive thermal exposure (RTE) technique. Mat material fatigue after several million cycles is evident by a substantial decrease in the transmitted force. A fragility test was found to be an excellent method to quickly compare candidate materials to be used for a specific application. Examples of test results from several materials are given to show the utility of the mat material evaluation technique.

In order to further reduce vehicle cold-start emissions, the use of catalytic converters that are “close-coupled” to the exhaust manifold is increasing. To understand the vibrational environment of close-coupled and underbody converters, a laboratory study was conducted on several passenger vehicles. Catalytic converter vibration spectra were measured on a chassis dynamometer with the vehicle operating over a variety of test conditions. Vehicle operating conditions included hard accelerations and extended steady-state speeds at distinct throttle positions over zero-percent and four-percent simulated road grades.

A push for more stringent emissions regulations has resulted in larger, increasingly complex aftertreatment solutions. In particular, oxides of nitrogen (NOX) and particulate matter (PM) have been controlled using two separate systems, selective catalytic reduction (SCR) and the catalyze diesel particulate filter (CDPF), or the functionality has been combined into a single device producing the SCR on filter (SCRoF). The SCRoF forgoes beneficial NO2 production present in the CDPF to avoid NH3 oxidation which occurs when using platinum group metals (PGM) for oxidation. In this study, mixed-metal oxides are shown to oxidize NO to NO2 without appreciable NH3 oxidation. This selectivity leads to enhanced performance when combined with a typical Cu-zeolite catalyst.

This paper describes a new method for measuring oil consumption using laser induced breakdown spectroscopy (LIBS). LIBS focuses a high energy laser pulse on a sample to form a transient plasma. As the plasma cools, each element produces atomic emission lines which can be used to identify and quantify the elements present in the original sample. In this work, a LIBS system was used on simulated engine exhaust with a focus on quantifying the inorganic components (termed ash) of the particulate emissions. Because some of the metallic elements in the ash almost exclusively result from lube oil consumption, their concentrations can also be correlated to an oil consumption rate. Initial testing was performed using SwRI’s Exhaust Composition Transient Operation Laboratory®(ECTO-Lab®) burner system so that oil consumption and ash mass could be precisely controlled.

The measurement of piston temperature in a reciprocating engine has historically been a very time-consuming and expensive process. Several conditions exist in an engine that measurement equipment must be protected against. Acceleration forces near 2000 G's occur at TDC in automotive engines at rated speed. Operating temperatures inside the crankcase can range to near 150°C. To allow complete mapping of piston temperature, several measuring locations are required in the piston and data must be obtained at various engine operating conditions. Southwest Research Institute (SwRI) has developed a telemetry-based system that withstands the harsh environments mentioned above. The device is attached to the underside of a piston and temperature data is transmitted to a receiving antenna in the engine crankcase. The key element of this device is a tiny power generator which utilizes the reciprocating motion of the piston to generate electricity thus allowing the transmitter to be self-powered.

Tier 2, bin 5 diesel engines may use multiple combustion modes to achieve stringent emissions requirements. Unfortunately, switching between different combustion modes can cause step changes in noise that will be unacceptable to consumers. In this paper, several sound quality metrics are evaluated for their ability to quantify the NVH issues that arise during a rich pulse event. In addition, techniques are presented that allow an engine developer to reduce the NVH effects caused by changing combustion modes. Careful calibration tuning in close cooperation with performance and emissions development engineers is required to solve noise problems that arise from combustion mode switching events, since an NVH improvement may often come at the expense of a performance or emissions issue.

This web course provides an in-depth overview of diesel engine noise including combustion and mechanical noise sources. In addition, the instructor will discuss a system approach to automotive integration including combining sub-systems and components to achieve overall vehicle noise and vibration goals.

This project’s objective was to generate experimental data to evaluate the impact of metals doped B20 on diesel particle filter (DPF) ash loading and performance compared to that of conventional petrodiesel. The effect of metals doped B20 vs. conventional diesel on a DPF was quantified in a laboratory controlled accelerated ash loading study. The ash loading was conducted on two DPFs – one using ULSD fuel and the other on B20 containing metals dopants equivalent to 4 ppm B100 total metals. Engine oil consumption and B20 metals levels were accelerated by a factor of 5, with DPFs loaded to 30 g/L of ash. Details of the ash loading experiment and on-engine DPF performance evaluations are presented in the companion paper (Part I). The DPFs were cleaned, and ash samples were taken from the cleaned material. X-ray Fluorescence (XRF), X-Ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD) were conducted on the ash samples.

Electromagnetic emissions (EME) from vehicles and their effect on broadcast radio and television were studied as early as 1944. Their original effect was significantly reduced by the early 1960s. Today, ignition noise (broadband) and vehicular micro-processor-controlled system noise (narrowband) are interfering with Land Mobile (two-way) communication services and other devices such as computers. Two SAE test methods, J551 and J1816, are used to measure this EME. Under development are methods to measure conducted EME on vehicle signal wiring and power input leads. This paper discusses EME measurement methods, provides insight into the sources of EME problems, and gives information on the test instrumentation used to make these measurements. This paper is the third in a series of papers on electromagnetic compatibility (EMC) in the off-highway vehicle. The first paper was an overview of a complete EMC program with discussion of several important segments.

The transport of fuel-borne additives into the engine oil is a critical factor for the efficacy with which the additive functionality can be imparted on the engine. This paper describes the combination of Laser Induced Fluorescence (LIF) and Liquid Chromatography (LC) to determine the real-time additive concentrations and transfer ratios in a spark-ignition, 2-liter GM LHU engine. The current research used a continuous sample circuit from the engine sump which passed through an integrating cavity flow cell to enhance the LIF signal. In the absence of a fluorescence signature of any of the native additive species, a suitable fluorescing dye was selected to simulate the additive. After establishing rigorous calibration curves, LC was employed as a referee method to do a direct comparison with the LIF determined dye concentrations.

This paper describes a hybrid robust nonlinear control approach for modern diesel engines running low temperature combustion and conventional diesel combustion modes. Using alternative combustion modes has become a promising approach to reduce engine emissions. However, due to very different in-cylinder conditions and fueling parameters for different combustion modes, control of engines operating multiple combustion modes is very challenging. It becomes difficult for conventional calibration / mapping based approaches to produce satisfactory results in terms of engine torque responses and emissions. Advanced control techniques are then demanded to accomplish the tasks. An innovative hybrid control system is designed to track different key engine operating variables at different combustion modes as well as avoid singularity which is inherent for turbocharged diesel engines running multiple combustion modes.

Excessive interior noise and vibration in propeller driven general aviation aircraft can result in poor pilot communications with ground control personnel and passengers, and, during extended flights, can lead to pilot and passenger fatigue. Noise source/path identification technology applicable to single engine propeller driven aircraft were employed to identify interior noise sources originating from structure-borne engine/propeller vibration, airborne propeller transmission, airborne engine exhaust noise, and engine case radiation. The approach taken was first to conduct a Principal Value Analysis (PVA) of an in-flight noise and vibration database acquired on a single engine aircraft to obtain a correlated data set as viewed by a fixed set of cabin microphones.

High-speed movie films, and laser-diffraction drop sizing were used to evaluate the structure, penetration rate, cone angle, and drop size distribution of diesel sprays in a constant volume pressure vessel. As further means of evaluating the data, comparisons are made between the film measurements, and calculations from a dense gas jet model. In addition to the high-speed film data that describes the overall structure of the spray as a function of time, a laser diffraction instrument was used to measure drop size distribution through a cross-section of the spray. In terms of the growth of the total spray volume (a rough measure of the amount of air entrained in the spray), spray impingement causes an initial delay, but generally the same overall growth rate as an equivalent unimpeded spray. Agreement between measurements and calculations is excellent for a diesel spray with a 0.15 mm D orifice and relatively high injection pressures.

Copper ion exchange procedures were used to prepare zeolite-based catalysts for NOx reduction in lean (oxygen-rich) exhaust. Energy dispersive x-ray fluorescence and scanning electron microscopy analyses confirmed the presence of copper in the zeolite matrix. Zeolites were applied onto honeycomb and foam substrates, and evaluated for catalytic NOx reduction efficiency using engine exhaust. Copper-exchanged zeolite catalysts prepared for this study revealed NOx reduction of 95 percent for a period of seven minutes using previously adsorbed exhaust hydrocarbons as the reducing agent. Experiments using ethylene injection to supplement the exhaust suggest long-term and sustained NOx reduction, initially observed at 52 percent. Experimental results and performance comparisons of ZSM-5, mordenite, and Y-type zeolites are discussed. Zeolite catalysts based on Cu-mordenite showed high levels of initial NOx reduction, while results using Cu-ZSM-5 suggested better long-term activity.

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.

Small engines may require soundproofing to eliminate one or more of the following effects: hearing loss, speech interference, community annoyance, detectability, and psychological disorientation. Detectability criteria are frequently associated with military applications and may require the use of a soundproof enclosure in addition to other engine treatments. Acoustical noise sources are conveniently classed as either aerodynamic or mechanical. Aerodynamic sources are predominant on small engines. Treatment of exhaust noise by individual components, e.g., muffler, is inadequate; a system approach, through the use of an electro-acoustic analog computer, has proved to be a much more satisfactory procedure.