Engine Power Levels Research Articles

Highly time-resolved heat flux measurement in a combustion engine

In this study a fast-response Atomic Layer Thermopile (ALTP) based heat flux measurement system is used for wall heat-flux determination in the combustion chamber of a commercially available SI-gasoline combustion engine. The ALTP system provides further process variables that supplement conventional cylinder pressure data with data that are highly resolved in time and location. The newly developed sensor modules were precisely calibrated and compared with other measurement techniques with radiation- and convection-based procedures. Quantitative highly time-resolved measurements with frequency resolutions up to 1 MHz are performed in the engine from low to full load and up to full speeds. Single-cycle and cycle-to-cycle measurements display the quality and high temporal resolution of the measurement system. The comparison of pressure and the heat-flux measurements shows the benefits of ALTPs for detection of engine, combustion and flow characteristics. The time progression of the heat flux curves and their autocorrelated signals show only minor noise interference. The measured results display significantly higher local peak heat flux densities with values up to 1250 Wcm−2 for certain measurement points and engine conditions than reported previously in literature for SI engines. A regression analysis suggests that the high peak heat flux densities obtained are caused by the significant higher engine power-levels per cylinder. The measured data compare well with regressions extrapolated from reported literature data. A provided uncertainty analysis revealed significant influencing parameters. The variation of thermal wall parameters with 20%–30% uncertainty are playing an essential role in particular.

Nitrogen oxide emission calculation for post-Panamax container ships by using engine operation power probability as weighting factor: A slow-steaming case

ABSTRACTIn this study, the nitrogen oxide (NOx) emission factors and total NOx emissions of two groups of post-Panamax container ships operating on a long-term slow-steaming basis along Euro–Asian routes were calculated using both the probability density function of engine power levels and the NOx emission function. The main engines of the five sister ships in Group I satisfied the Tier I emission limit stipulated in MARPOL (International Convention for the Prevention of Pollution from Ships) Annex VI, and those in Group II satisfied the Tier II limit. The calculated NOx emission factors of the Group I and Group II ships were 14.73 and 17.85 g/kWhr, respectively. The total NOx emissions of the Group II ships were determined to be 4.4% greater than those of the Group I ships. When the Tier II certification value was used to calculate the average total NOx emissions of Group II engines, the result was lower than the actual value by 21.9%. Although fuel consumption and carbon dioxide (CO2) emissions were increased by 1.76% because of slow steaming, the NOx emissions were markedly reduced by 17.2%. The proposed method is more effective and accurate than the NOx Technical Code 2008. Furthermore, it can be more appropriately applied to determine the NOx emissions of international shipping inventory.Implications: The usage of operating power probability density function of diesel engines as the weighting factor and the NOx emission function obtained from test bed for calculating NOx emissions is more accurate and practical. The proposed method is suitable for all types and purposes of diesel engines, irrespective of their operating power level. The method can be used to effectively determine the NOx emissions of international shipping and inventory applications and should be considered in determining the carbon tax to be imposed in the future.

Diesel engine vibration monitoring based on a statistical model

There are various causes for vibrations on diesel engines. The engine vibrations depend not only on the present state of the engine, but also on the fuel quality, the environmental conditions (sea state in the case of shipborne engines), type of casing, other equipment in the vicinity, etc. The engines used for this study are installed aboard a ship, and the main aim is to use modified control charts to assess the condition of the engine and recommend corrective measures when necessary. An important issue to do this correctly is choosing the right places to measure vibration. The collected data is vibration at various engine power levels, measured at various points. The engine’s fault history is taken into consideration, but proved to be almost irrelevant. By using modified control charts, the engine vibrations can be estimated, and faults can be detected and classified so as to take corrective actions. In this study we followed a methodology that is slightly different from our previous work, and achieved good results.

Turbofan Engine Health Assessment From Flight Data

The paper presents the use of different approaches to engine health assessment using on-wing data obtained over a year from an engine of a commercial short-range aircraft. The on-wing measurements are analyzed with three different approaches, two of which employ two models of different quality. Initially, the measurements are used as the sole source of information and are postprocessed utilizing a simple “model” (a table of corrected parameter values at different engine power levels) to obtain diagnostic information. Next, suitable engine models are built utilizing a semi-automated method which allows for quick and efficient creation of engine models adapted to specific data. Two engine models are created, one based on publicly available data and one adapted to engine specific on-wing “healthy” data. These models of different details are used in a specific diagnostic process employing model-based diagnostic methods, namely the probabilistic neural network (PNN) method and the deterioration tracking method. The results demonstrate the level of diagnostic information that can be obtained for this set of data from each approach (raw data, generic engine model or adapted to measurements engine model). A subsystem fault is correctly identified utilizing the diagnostic process combined with the engine specific model while the deterioration tracking method provides additional information about engine deterioration.

Study of a Novel Air-augmented Waterjet Boost Concept

This research presents analysis, experiment, and prediction of the performance of a unique marine propulsion concept, the air-augmented waterjet, having a revolutionary potential for significant thrust augmentation and boost capability of waterjet systems. So far, this concept has not been realized in any operational vessel. The air-augmented waterjet propulsion concept is similar to an after-burner in the aeronautical turbojet engine. The thrust augmentation results from the injection of air bubbles into the water flow, converting their expansion work òpdV into additional kinetic energy of the exhaust jet without affecting the pump operation. It can enable substantially augmenting boost capability, overcoming hump resistance, and increasing maximum attainable vessel speed while avoiding cavitation problems. Static tests at the Technion's water tank, using a jetski waterjet engine of a nominal power of 50 kW, have been conducted with and without air injection over a range of motor revolutions per minute (rpm). The addition of air increased the thrust by 20% to 50% depending on the airflow rate and engine rpm. Air expansion work increased the exhaust jet kinetic energy at an efficiency of 70% approximately. Based on the static experiments, prediction of the system behavior for different vessel speeds and engine power levels has been made, revealing a higher relative thrust augmentation for the same pump power and airflow rate at higher vessel speeds. The air-augmented waterjet concept may add a new dimension to marine propulsion as well as upgrade existing vessels.

Study of a Novel Air-augmented Waterjet Boost Concept

This research presents analysis, experiment, and prediction of the performance of a unique marine propulsion concept, the air-augmented waterjet, having a revolutionary potential for significant thrust augmentation and boost capability of waterjet systems. So far, this concept has not been realized in any operational vessel. The air-augmented waterjet propulsion concept is similar to an after-burner in the aeronautical turbojet engine. The thrust augmentation results from the injection of air bubbles into the water flow, converting their expansion work ∫pdV into additional kinetic energy of the exhaust jet without affecting the pump operation. It can enable substantially augmenting boost capability, overcoming hump resistance, and increasing maximum attainable vessel speed while avoiding cavitation problems. Static tests at the Technion's water tank, using a jetski waterjet engine of a nominal power of 50 kW, have been conducted with and without air injection over a range of motor revolutions per minute (rpm). The addition of air increased the thrust by 20% to 50% depending on the airflow rate and engine rpm. Air expansion work increased the exhaust jet kinetic energy at an efficiency of 70% approximately. Based on the static experiments, prediction of the system behavior for different vessel speeds and engine power levels has been made, revealing a higher relative thrust augmentation for the same pump power and airflow rate at higher vessel speeds. The air-augmented waterjet concept may add a new dimension to marine propulsion as well as upgrade existing vessels.

Aircraft engine particulate matter: Macro- micro- and nanostructure by HRTEM and chemistry by XPS

Carbonaceous particulate emissions from jet aircraft are a significant source of emissions from airports near urban areas. Physical structure and surface chemistry are relevant towards assessing impacts of combustion-produced soot upon the environment and assessing health impacts. In this report high-resolution electron microscopy (HRTEM) and X-ray photoelectron (XPS) data are presented for particulate emissions from a CFM-56-3 engine aboard a DC-9 aircraft, fueled by JP-8. Engine power levels were varied from 4% to 100%. Soot aggregate macrostructure, microstructure and nanostructure are discussed with respect to combustion conditions. Ultrafine particle size distributions at idle and near full power conditions are highlighted by HRTEM and compare favorably to reported scanning mobility particle sizer (SMPS) measurements. Particle composition, as inferred from the XPS ratio for sp2/sp3 carbon bonding is compared to results from thermo-optical evaluation of organic and elemental carbon analysis at selected powers with excellent agreement. Across engine power levels, these ultra-fine particles appear to be remnants of oxidized larger aggregates.

Insights into the combustion chemistry within a gas-turbine driven auxiliary power unit as a function of fuel type and power level using soot nanostructure as a tracer

Particulate emissions were collected from an Auxiliary power unit (APU) directly upon TEM grids for particle characterization by HRTEM. Carbonaceous emissions from two fuels, a coal-based Fischer–Tropsch and standard JP-8 were compared, each at three power levels. Differences in soot nanostructure, specifically fullerenic content reveal changes in the combustion chemistry with engine power level, as do differences in aggregate size between the two fuels. As inferred from the soot nanostructure, comparison between fuels demonstrates the impact of fuel structure upon soot formation chemistry.

Minimizing Sampling Loss in Trace Gas Emission Measurements for Aircraft Engines by Using a Chemical Quick-Quench Probe

This paper describes the development and testing of a gas sampling probe that quenches chemical reactions by using supersonic expansion and helium dilution. Gas sampling probes are required for accurate measurement of exhaust emissions species, which is critical to determine the performance of an aircraft engine. The probe was designed through rounds of computational modeling and laboratory testing and was subsequently manufactured and then tested at the University of Tennessee Space Institute behind a General Electric J85 turbojet engine at different power settings: idle, maximum military, and afterburning. The experimental test results demonstrated that the chemical quick-quench (CQQ) probe suppressed the oxidation of carbon monoxide (CO) inside the probe system and preserved more CO at afterburning conditions. In addition, the CQQ probe prevented hydrocarbons from being partially oxidized to form CO at idle powers and measured higher hydrocarbons and lower CO emission compared with a conventional probe at that low power condition. The CQQ probe also suppressed nitrogen dioxide (NO2) to nitric oxide (NO) conversion through all engine power settings. These data strongly support the conclusion that the CQQ probe is able to quench unwanted chemical reactions inside the probe for all engine power levels.

ATATÜRK ÜNİVERSİTESİ ZİRAAT FAKÜLTESİ TARIM İŞLETMESİ BİTKİSEL ÜRETİM ALANI İÇİN EN UYGUN MEKANİZASYON MODELİNİN TESPİTİ

OZET Bu arastirmada, Ataturk Universitesi Ziraat Fakultesi Tarim Isletmesi bitkisel uretim alani icin en uygun mekanizasyon modelinin belirlenmesi amaclanmistir. Bu amacla; isletme icin en uygun bitki cesitleri ile bu bitkilerin maksimum ekilis alanlari, bitkilere iliskin tarimsal islemlerde kullanilacak alet ve makinalar, alet ve makinalara uygun traktor gucleri, uretimde kullanilan girdilere iliskin giderler, birim alan gelirleri, makina isgucu istegi bakimindan yogun olan calisma donemleri, bu donemlerde calisilabilir gun sayilari ve gunluk caltsma sureleri gozonunde bulundurularak bir dogrusal programlama modeli olusturulmustur, 35, 47 ve 59 kW guclerindeki traktorler ile bu traktorlere uygun 22 farkli alet-makina ve bicerdoverin bir araya gelmesiyle elde edilen uc farkli makina setinin yer aldigi modelin simpleks yontem kullanilarak bilgisayarda cozume kavusturulmasi sonucu; Set-A olarak belirtilen 35 kW guce sahip traktor ile bu guce uygun tarim makinalari seti isletmenin net kârini maksimize etmistir. Maksimum kârin elde edildigi urun deseni de; 420 ha bugday, 208 ha arpa, 207 ha cayir, 107 ha yonca, 176 ha patates ve 138 ha seker pancari seklinde olmustur. THE DETERMINING OF THE OPTIMUM MECHANISATION MODEL FOR CROP PRODUCTION OF THE FARM OF ATATURK UNIVERSITY AGRICULTURE FACULTY SUMMARY In this study, the optimum machinery system for thefarm of Ataturk Untversity Agriculture Faculty vvas determined. Cons ide ring the properties of thefarm and the crop pattern, the size of machinery and tractors selected.in order to determine tractor engine po\ver levels, the tractors widely used in Turkey was considered. So, three tractor engine power levels of 35, 47 and 59 k,W were determined and three various machinery systems which ar e proper to these levels were selected. W hile determining these machinery systems, the maximum PTO power was considered 90 percent of maximum engine power. if the load size exceeded 85 percent of mcaimum PTO power, the machinery size was reduced to the nekst smaller size. Considering the yield, the costs of production inputs, number of available days, daily working time, the technical properties of machinery and the other management properties, a linear programming model vvas developed for solving the problem by the simpleks algorithm. in the result, machinery System-A included a 35 k,W tractor and matching machinery maximized the net profit of form. The production pattern is 420 ha \vheat, 208 ha barley, 207 ha pasture, 107 ha alfalfa, 176 ha potato and 138 ha sugar beet. According to the results of the study, the following suggests must be considered : Work organization must be made for a productive and profitable mechanization management. Traktor running hours must be recorded, so thedata bank for mechanization planning must be provided. Technical and management properties of the machinery system must be considered during using. Suggested machinery system must be used to carry properly the agr'icultural activities oiit at the optimum periods. Ali thefield ofthefarm must be smoothedso that machinery can be effectively used and the irrigation applications can be easily made. In order to determine, use and product the machinery obtained maximum efficiency from tractor power, a coordination must be made between the manufacturers and the farmers. All the sources must be effectively used in the farm

Design Parameters for an Aircraft Engine Exit Plane Particle Sampling System

The experimental data and numerical modeling were utilized to investigate the effects of exhaust sampling parameters on the measurements of particulate matter (PM) emitted at the exit plane of gas-turbine engines. The results provide guidance for sampling system design and operation. Engine power level is the most critical factor that influences the size and quantity of black carbon soot particles emitted from gas-turbine engines and must be considered in sampling system design. The results of this investigation indicate that the available soot surface area significantly affects the amount of volatile gases that can condense onto soot particles. During exhaust particle measurements, a dilution gas is typically added to the sampled exhaust stream to suppress volatile particle formation in the sampling line. Modeling results indicate that the dilution gas should be introduced upstream before a critical location in the sampling line that corresponds to the onset of particle formation microphysics. Also, the dilution gas should be dry for maximum nucleation suppression. In most aircraft PM emissions measurements, the probe-rake systems are water cooled and the sampling line may be heated. Modeling results suggest that the water cooling of the probe tip should be limited to avoid overcooling the sampling line wall temperature and, thus, minimize additional particle formation in the sampling line. The experimental data show that heating the sampling lines will decrease black carbon and sulfate PM mass and increase organic PM mass reaching the instruments. Sampling line transmission losses may prevent some of the particles emitted at the engine exit plane from reaching the instruments, especially particles that are smaller in size. Modeling results suggest that homogeneous nucleation can occur in the engine exit plane sampling line. If newly nucleated particles, typically smaller than 10 nm, are indeed formed in the sampling line, sampling line particle losses provide a possible explanation, in addition to the application of dry diluent, that they are generally not observed in the PM emissions measurements.

Vapour-phase and particulate-bound PAHs profile generated by a (SI/HCCI) engine from a winter grade commercial gasoline fuel

The vapour-phase and particulate-bound Aromatic Hydrocarbons, PAHs, generated by a V6 gasoline engine working in spark-ignition (SI) and homogeneous charge compression ignition (HCCI) modes were collected and analysed. All data were obtained during steady-state, fully warmed-up operation at different engine power levels (low and medium loads and mid-speed), and two different engine operation modes (SI and HCCI). The fuel used in this study was winter grade commercial gasoline fuel. The vapour-phase exhaust gases were passed through stainless-steel cartridges containing XAD-2 resin to capture PAHs. The PAHs were extracted from the resin with dichloromethane in an ultrasonic bath, the obtained extracts were later analysed qualitatively and quantitatively by GC–MS. The vapour-phase PAHs compounds observed from HCCI mode operated in low load were Naphthalene, Acenaphthylene and Acenaphthene only, while that obtained from SI mode under low load were Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Anthracene, Phenanthrene, Fluoranthene and Pyrene. The PAHs bound to particulates were trapped by using a complex of dilution tunnels with filter papers. The soluble organic fractions (SOF) of the trapped particulates were separated from the insoluble fraction (ISF) with the help of ultrasonic elution, and analysed by GC–MS method. The most abundant PAHs detected under selected operation condition for HCCI mode was Benzo[a]anthracene, followed by Chrysene, then Pyrene and pursued by Benzo[b]fluoranthene, in SI mode under same operation condition the highest PAH detected was Benzo[a]anthracene followed by Pyrene, Benzo[b]fluoranthene and Chrysene. Probable mechanisms for the production of some of the pyrosynthetic PAH were discussed.

Extractive Sampling and Optical Remote Sensing of F100 Aircraft Engine Emissions

The Strategic Environmental Research and Development Program (SERDP) has initiated several programs to develop and evaluate techniques to characterize emissions from military aircraft to meet increasingly stringent regulatory requirements. This paper describes the results of a recent field study using extractive and optical remote sensing (ORS) techniques to measure emissions from six F-15 fighter aircraft. Testing was performed between November 14 and 16, 2006 on the trim-pad facility at Tyndall Air Force Base in Panama City, FL. Measurements were made on eight different F100 engines, and the engines were tested on-wing of in-use aircraft. A total of 39 test runs were performed at engine power levels that ranged from idle to military power. The approach adopted for these tests involved extractive sampling with collocated ORS measurements at a distance of approximately 20–25 nozzle diameters downstream of the engine exit plane. The emission indices calculated for carbon dioxide, carbon monoxide, nitric oxide, and several volatile organic compounds showed very good agreement when comparing the extractive and ORS sampling methods.

On the Concept of Separate Aftercooling for Locomotive Diesel Engines

This paper describes a patented cooling system concept for a turbocharged diesel engine. In particular, it defines a cooling system having the capability of transferring some of the cooling capacity of engine jacket and engine oil cooling to cool the cylinder inlet air when more than the cooling capacity built into the system through the size of the radiators and fans is needed. This increased aftercooling will improve the engine performance and reduce emission levels. The cooling capacity of a locomotive is essentially determined by the radiator and fan size, among other factors, and is designed to cool the engine within acceptable metal temperatures at a specified maximum ambient temperature and at the maximum engine power. On the other hand, at lower ambient temperatures or engine power levels, the cooling needs of the engine will be less than this maximum cooling capacity of the cooling system. There remains some excess capacity. This paper describes the concept called the “Separate Aftercooling System” that uses some of this excess cooling capacity to cool the engine inlet air at the aftercoolers. It shows the feasibility of such a system, describes the order of magnitude of benefits that can be expected from such a system, and outlines the implementation of this concept to EMD built Locomotives.

Diode laser-based air mass flux sensor for subsonic aeropropulsion inlets

An optical air mass flux sensor based on a compact, room-temperature diode laser in a fiber-coupled delivery system has been tested on a full-scale gas turbine engine. The sensor is based on simultaneous measurements of O(2) density and Doppler-shifted velocity along a line of sight across the inlet duct. Extensive tests spanning engine power levels from idle to full afterburner demonstrate accuracy and precision of the order of 1-2% of full scale in density, velocity, and mass flux. The precision-limited velocity at atmospheric pressure was as low as 40 cm/s. Multiple data-reduction procedures are quantitatively compared to suggest optimal strategies for flight sensor packages.

Multivariable Adaptive Control Using Only Input and Output Measurements for Turbojet Engines

Current and future aircraft engines are increasingly relying upon the use of multivariable control approach for meeting advanced performance requirements. A multivariable model reference adaptive control (MRAC) scheme is proposed in this paper. The adaptation law is derived using only input and output (I/O) measurements. Simulation studies are performed for a two-spool turbojet engine. The satisfactory transient responses are obtained at different operating points from idle to maximum dry power within the flight envelope. These show insensitivity of the design to engine power level and flight condition. Simulation results also show high effectiveness of reducing interaction in multivariable systems with significant coupling. Using the multivariable MRAC controller, the engine acceleration time is reduced by about 19 percent in comparison with the conventional engine controller.

Chemical composition and photochemical reactivity of exhaust from aircraft turbine engines

Abstract. Assessment of the environmental impact of aircraft emissions is required by planners and policy makers. Seveal areas of concern are: 1. exposure of airport workers and urban residents to toxic chemicals emitted when the engines operate at low power (idle and taxi) on the ground; 2. contributions to urban photochemical air pollution of aircraft volatile organic and nitrogen oxides emissions from operations around airports; and 3. emissions of nitrogen oxides and particles during high-altitude operation. The environmental impact of chemicals emitted from jet aircraft turbine engines has not been firmly established due to lack of data regarding emission rates and identities of the compounds emitted. This paper describes an experimental study of two different aircraft turbine engines designed to determine detailed organic emissions, as well as emissions of inorganic gases. Emissions were measured at several engine power settings. Measurements were made of detailed organic composition from C1 through C17, CO, CO2, NO, NOx, and polycyclic aromatic hydrocarbons. Measurements were made using a multi-port sampling pro be positioned directly behind the engine in the exhaust exit plane. The emission measurements have been used to determine the organic distribution by carbon number and the distribution by compound class at each engine power level. The sum of the organic species was compared with an independent measurement of total organic carbon to assess the carbon mass balance. A portion of the exhaust was captured and irradiated in outdoor smog chambers to assess the photochemical reactivity of the emissions with respect to ozone formation. The reactivity of emissions from the two engines was apportioned by chemical compound class.

Low Emissions from Controlled Combustion for Automotive Rankine Cycle Engines

Rankine cycle engines have a high potential for meeting the emission levels established by the 1970 amendment to the Federal Clean Air Act for the 1975-76 automobile. This paper discusses a Solar research and development program sponsored by EPA/APCO which demonstrates a full scale 2 million Btu per hour working model of a Rankine cycle engine combustor and controls which can surpass the emission goals established. Special features of the combustor are the unique methods of precisely controlling both the fuel and air to provide optimum flame performance at any engine power level. This paper discusses the special requirements of the Rankine cycle engine and shows why the very wide range of fuel flow required necessitates use. of special techniques in fuel atomization, fuel and air control, and aerodynamics. Sufficient discussion is included to show the design methods that are necessary, in general, to achieve low emissions in continuous flow combustion systems. Emphasis is placed on the importance of inter...