中冷回热涡扇航空发动机技术

中冷回热航空发动机(IRA)是在简单发动机循环基础上加入中冷和回热两个环节,有效利用了发动机热量,提高了发动机热效率,降低了耗油率,是新概念的节能环保航空发动机,中冷回热航空发动机的研究为我国大飞机发动机总体性能设计提供了重要参考。

关于实施《车用点燃式发动机及装用点燃式发动机汽车排气污染物排放限值及测量方法》等四项国家污染物排放标准有关要求的通知

各省、自治区、直辖市环境保护局(厅),各有关单位:为贯彻《中华人民共和国大气污染防治法》,严格控制机动车污染物排放,我局于2002年11月发布了《车用点燃式发动机及装用点燃式发动机汽车排气污染物排放限值及测量方法》(GB 14762—2002)、《摩托车排气污染物排放限值及测量方法(工况法)》(GB 14622—2002)、《轻便摩托车排气污染物排放限值及测量方法(工况法)》(GB 18176—2002)和《摩托车和轻便摩托车排气污染物排放限值及测量方法(怠速法)》(GB14621—2002)等四项标准,并已于2003年1月1日正式实施。现将实施标准的有关要求通知如下:一。

国家环境保护总局关于发布《兵器工业水污染物排放标准 火工药剂》等三项与《车用点燃式发动机及装用点燃式发动机汽车排气污染物排放限值及测量方法》等四项国家污染物排放标准的公告

国家环境保护总局2002年11月18日以环发[2002]161号文发出“关于发布《兵器工业水污染物排放标准 火工药剂》等三项国家污染物排放标准的公告”,“公告”内容如下: 为贯彻《中华人民共和国水污染防治法》,防治水污染,保护水资源,保障人体健康,加强环境管理,现批准《兵器工业水污染物排放标准 火工药剂》。

国外TBCC关键技术及试验设备研究综述

从空气动力学角度系统梳理了TBCC发动机研究需攻克的关键技术,并论述了国外开展相关研究建设的重要试验设备。其中,关键技术主要包括进气道技术、模态转换技术、高马赫数涡轮发动机技术和尾喷管技术;试验设备主要包括单项技术攻关设备、关键部件验证设备、缩比原理机验证设备和全尺寸样机验证设备。从国外开展TBCC发动机关键技术和试验设备建设的研究中得到几点启示,可为我国进行TBCC发动机研制提供参考及借鉴。

高超音速飞行器及其关键技术简论

简要评述了高超音速飞行器及其关键技术,包括:高超音速飞行的定义、高超音速流动的特征、高超飞行覆盖范围、高超飞行器蒙皮温度、以及高超飞行设计特点;高超飞行器的背景;高超飞行器研制的发展简史,及经验与思考;吸气式高超飞行器典型设计过程、发展战略、技术规划、和关键技术领域.

更快更好地完成曲轴的磨削加工

AER公司在一天内生产几百种不同型号发动机。随着生产计划的改变。他们一直面临着如何平衡生产过程中的柔性生产、提高质量及生产效率三者关系的问题，根据OEM制造商的工艺要求，这些问题特别体现在曲轴的磨削加工工艺中。

Effect of exhaust gas recirculation and intake pre-heating on performance and emission characteristics of dual fuel engines at part loads

Achieving simultaneous reduction of NOx,CO and unburned hydrocarbon(UHC) emissions without compromising engine performance at part loads is the current focus of dual fuel engine research.The present work focuses on an experimental investigation conducted on a dual fuel(diesel-natural gas) engine to examine the simultaneous effect of inlet air pre-heating and exhaust gas recirculation(EGR) ratio on performance and emission characteristics at part loads.The use of EGR at high levels seems to be unable to improve the engine performance at part loads.However,it is shown that EGR combined with pre-heating of inlet air can slightly increase thermal efficiency,resulting in reduced levels of both unburned hydrocarbon and NOx emissions.CO and UHC emissions are reduced by 24% and 31%,respectively,The NOx emissions decrease by 21% because of the lower combustion temperature due to the much inert gas brought by EGR and decreased oxygen concentration in the cylinder.

Numerical investigations on HCCI engine with increased induction induced swirl and engine speed

Homogeneous charge compression ignition(HCCI) mode of combustion is popularly known for achieving simultaneous reduction of NOx as well as soot emissions as it combines the compression ignition(CI) and spark ignition(SI) engine features. In this work, a CI engine was simulated to work in HCCI mode and was analyzed to study the effect of induction induced swirl under varying speeds using three-zone extended coherent flame combustion model(ECFM-3Z, compression ignition) of STAR-CD. The analysis was done considering speed ranging from 800 to 1600 r/min and swirl ratios from 1 to 4. The present study reveals that ECFM-3Z model has well predicted the performance and emissions of CI engine in HCCI mode. The simulation predicts reduced in-cylinder pressures, temperatures, wall heat transfer losses, and piston work with increase in swirl ratio irrespective of engine speed. Also, simultaneous reduction in CO2 and NOx emissions is realized with higher engine speeds and swirl ratios. Low speeds and swirl ratios are favorable for low CO2 emissions. It is observed that increase in engine speed causes a marginal reduction in in-cylinder pressures and temperatures. Also, higher turbulent energy and velocity magnitude levels are obtained with increase in swirl ratio, indicating efficient combustion necessitating no modifications in combustion chamber design. The investigations reveal a total decrease of 38.68% in CO2 emissions and 12.93% in NOx emissions when the engine speed increases from 800 to 1600 r/min at swirl ratio of 4. Also an increase of 14.16% in net work done is obtained with engine speed increasing from 800 to 1600 r/min at swirl ratio of 1. The simulation indicates that there is a tradeoff observed between the emissions and piston work. It is finally concluded that the HCCI combustion can be regarded as low temperature combustion as there is significant decrease in in-cylinder temperatures and pressures at higher speeds and higher swirl ratios.

Performance evaluation of a diesel engine by using producer gas from some under-utilized biomass on dual-fuel mode of diesel cum producer gas

Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resources in India.Experiments were conducted to study the performance of a diesel engine(four stroke,single cylinder,5.25 kW) with respect to its thermal efficiency,specific fuel consumption and diesel substitution by use of diesel alone and producer gas-cum-diesel(dual fuel mode).Three types of biomass,i.e.wood chips,pigeon pea stalks and corn cobs were used for generation of producer gas.A producer gas system consisting of a downdraft gasifier,a cooling cum cleaning unit,a filtering unit and a gas air mixing device was designed,fabricated and used to power a 5.25 kW diesel engine on dual fuel mode.Performance of the engine was reported by keeping biomass moisture contents as 8%,12%,16%,and 21%,engine speed as 1 600 r/min and with variable engine loads.The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode.The specific diesel consumption was found to be 60%-64% less in dual fuel mode than that in diesel mode for the same amount of energy output.The average diesel substitution of 74% was observed with wood chips followed by corn cobs(78%) and pigeon pea stalks(82%).Based on the performance studied,the producer gas may be used as a substitute or as supplementary fuel for diesel conservation,particularly for stationary engines in agricultural operations in the farm.

Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied.The quantity and forms of its sealing surfaces are reduced and simplified,and what's more,the advantages of twin-rotor piston engine are inherited,such as high power density and no valve mechanism.Given the motion law of two rotors,its kinematic model is established,and the general expression for some parameters related to engine performance,such as the trajectory,displacement,velocity and acceleration of the piston and centroid trajectory,angular displacement,velocity and acceleration of the rod are presented.By selecting different variation patterns of relative angle of two rotors,the relevant variables are compared.It can be concluded that by designing the relative angle function of two rotors,the volume variation of working chamber can be changed.However,a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions,the swing magnitude of rod is proportional to link ratio λ,and the position of rod swing center is controlled by eccentricity e.In order to reduce the lateral force,a smaller value of λ should be selected in the case of the structure,and the value of e should be near 0.95.There is no relationship between the piston stroke and the variation process of relative angle of two rotors,the former is only proportional to the amplitude of relative angle of two rotors.

Modelling of modern automotive petrol engine performance using Support Vector Machines

Modern automotive petrol engine performance is significantly affected by effective tune-up. Current practice of engine tune-up relies on the experience of the automotive engineer, and tune-up is usually done by trial-and-error method and then the vehicle engine is run on the dynamometer to show the actual engine performance. Obviously the current practice involves a large amount of time and money, and then may even fail to tune up the engine optimally because a formal performance model of the engine has not been determined yet. With an emerging technique, Support Vector Machines (SVM), the approximate per- formance model of a petrol vehicle engine can be determined by training the sample engine performance data acquired from the dynamometer. The number of dynamometer tests for an engine tune-up can therefore be reduced because the estimated engine performance model can replace the dynamometer tests to a certain extent. In this paper, the construction, validation and accuracy of the model are discussed. The study showed that the predicted results agree well with the actual test results. To illustrate the significance of the SVM methodology, the results were also compared with that regressed using multilayer feedforward neural networks.

Matching between mechanics and thermodynamics among 4 individual strokes in a 4-stroke engine by non-circular gear mechanism

The relationship between engine mechanics and thermo-dynamics has been investigated by means of numerical simulation.The inherent mismatching between the mechanical behaviors and the thermodynamic process in internal combustion engine is identified,which is believed to be one of the important limiting factors of energy efficiency for conventional engines available in the current market.An approach for engine efficiency improvement through optimal matching between mechanics and thermodynamics(OMBMT)is proposed.An ideal matching model is defined and the conflicts due to the constraints among the mapping strokes in a 4-stroke engine are analyzed.A novel mechanical model is built for approaching optimal matching among all 4 individual strokes in a 4-stroke spark-ignition engine,which is composed of non-circular gears(NCG)and integrated with conventional slider crank engine mechanism.By means of digital mechanical model and numerical simulation,the matching gains among all 4 strokes are defined and calculated for quantifying the NCG engine efficiency improvement by comparing with a baseline engine.The potentials with the OMBMT implemented and the enhancements made by NCG mechanism for engines in terms of overall engine efficiency are reported.Based on the results achieved,it is recommended that the feasibility studies and the experimental validations should be conducted to verify the engine matching concept and effectiveness of the NCG mechanism engine model proposed,and the engine performance and NCG design parameters should be further optimized.

Theoretical study on the ideal open cycle of the liquid nitrogen engine

This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.

Gas Turbine Operation Offshore： Online Compressor Wash Operational Experience

Online compressor wash for six GE LM2500PE engines at a Statoil North Sea offshore field is analyzed. Three engines are generator drivers whilst three engines are compressor drivers. Two of the compressor drive engines are running at peak load （T5.4-control）, hence production rate is limited by the available power from these engines. All the six engines analyzed run continuously without redundancy, hence gas turbine uptime is critical for the field＇s production and economy. The performance and operational experience with on-line wash at different water-to-air ratios and engine loads, as well as economy potentials related to successful on-line wash are given. This work is based on long-term operation with on-line wash, where operational data are collected and performance analyzed, over a 4-5 year period. All engines are operated with four-month intervals between maintenance stops, where off-line crank-wash is performed as well as other necessary maintenance and repairs. On-line wash is performed daily between the maintenance stops at full load （i.e., normal operating load for the subject engine）. To keep the engine as clean as possible and reduce degradation between maintenance stops, both an effective on-line water wash system as well as effective air intake filter system, are critical factors. The overall target is to maintain high engine performance, and extend the interval between maintenance stops through effective on-line wash. It is of vital importance to understand the gas turbine performance deterioration. The trending of its deviation from the engine baseline facilitates load-independent monitoring of the gas turbine＇s condition. Engine response to water injection at different loads and water-to-air ratios, as well as engine response to compressor deterioration is documented and analyzed. Instrument resolution and repeatability are key factors required in order to obtain reliable performance analysis results. Offshore instrumentation on older installations is often limited to the necessary instruments for machine control/protection, and additional instruments for effective performance monitoring and analysis are often missing or, if installed, have less accuracy. As a result of these analyses, a set of monitoring parameters is proposed for effective diagnosis of compressor degradation. Avenues for further research and development are proposed in order to further increase the understanding of the deterioration mechanisms and the gas turbine performance and response.

One of the Scenarios for Reduction the Emission of Pollutants from Motor Vehicle in the Territory of the Republic of Kosovo

Together with development of the industry, there is present a continuous increase number of motor vehicles that contributes to the growth of the emission of pollutants. This is the main reason that during eighties of the last century, a special attention has started to be paid on pollution emissions from vehicles. It is important to note that most of the current emissions are formed directly and are present in urban areas. The aim of this research was to determine the emission of pollutants in the territory of the Republic of Kosovo, when circulates more than 380,000 motor vehicles. Taking into consideration the daily traffic jam, and the fact that gasoline engines are responsible for most emissions of CO, while diesel engines for NOx emission, the conclusion arises that there is necessary a special dedication to the emission of pollutants and to the definition of the measures to reduce or control them. Based on the performed tests and realistic assessment of the overall situation in the Republic of Kosovo, the current situation on the amount of pollution was compared with development countries in the region as a matter in the research. The results obtained, suggest to the most important causes that increase pollutant emission from motor vehicles and offer actions to keep the same level or to reduce them.

Mathematical modeling and analysis of gas torque in twin-rotor piston engine

The gas torque in a twin-rotor piston engine(TRPE) was modeled using adiabatic approximation with instantaneous combustion. The first prototype of TRPE was manufactured. This prototype is intended for high power density engines and can produce 36 power strokes per shaft revolution. Compared with the conventional engines, the vector sum of combustion gas forces acting on each rotor piston in TRPE is a pure torque, and the combustion gas rotates the rotors while compresses the gas in the compression chamber at the same time. Mathematical modeling of gas force transmission was built. Expression for gas torque on each rotor was derived. Different variation patterns of the volume change of working chamber were introduced. The analytical and numerical results is presented to demonstrate the main characteristics of gas torque. The results show that the value of gas torque in TRPE falls to be less than zero before the combustion phase is finished; the time for one stroke is 30° in terms of the rotating angle of the output shaft; gas torque in one complete revolution of the output shaft has a period which is equal to 60° and it is necessary to put off the moment when gas torque becomes zero in order to export the maximum energy.

Experimental Researches of a Hydrogen Fuelled SI Engine

The paper presents the results of the experimental research which was carried out on the spark ignition engine, experimental model, fuelled with hydrogen by direct injection method, using qualitative load adjustment method for engine running control. Also, the hydrogen injection solution at the beginning of the compression stroke, after the inlet valve closing, assures the cylinder cooling by inlet air avoiding in that way uncontrolled ignition phenomena and inlet back fire. Using this fueling method avoided the abnormally hydrogen combustion phenomena＇s for stoichiometric dosage operating conditions, achieving -30 % engine power increase. Hydrogen engine runs with very lean mixtures, due to engine load qualitative adjustment, a dosage value that leads to a reduction of the engine power with -25% from maximum power value. This provides a higher engine efficiency at low loads, the best results was obtained for λ=2- 4 air-fuel ratio values. The influence of the mixture quality on burning process, on polluting and energetically engine performances at the fuelling with hydrogen using direct injection method are presented. Because of the higher combustion temperature, the NOx emission level is higher for λ=1 - 2 comparative to gasoline fuelled engine, but decreases a lot for leaner mixture values, λ〉2.5.

Performance and Emission Characteristics of Tylosema Esculentum Biodiesel in a Diesel Engine： An Experimental Investigation

Biodiesel derived from indigenous feed stocks such as Tylosema esculentum kernel oil is deemed a feasible alternative to petroleum diesel for the diesel engine. This paper presents results of investigation of performance and emissions characteristics of diesel engine using Tylosema biodiesel. In this investigation, Tylosema biodiesel was prepared, analyzed and compared with the performance of petroleum diesel fuel using a single cylinder compression ignition diesel engine. The specific fuel consumption, engine torque, engine brake power, hydrocarbons, carbon monoxide and carbon dioxide were analyzed. The tests showed a decrease in engine brake power and torque with increase in engine load, while specific fuel consumption showed an increasing trend with maximum variation of 33% between the two fuels at engine load of 90%. Emission levels of hydrocarbons, carbon monoxide and carbon dioxide showed an increasing trend with increase in load for both fuels. Tylosema biodiesel produced significantly lower concentrations of hydrocarbons than petroleum diesel, while levels of carbon dioxide and carbon monoxide were largely comparable to those of petroleum diesel. Soot production from combustion ofTylosema biodiesel was found to be approximately 98% lower than that from combustion of petroleum biodiesel, demonstrating insignificant contribution to environmental pollution.

Investigation on Emission and Combustion with 100% Palm Kernel Methyl Ester as Fuel on VCR-DI-Diesel Engine

Methyl or ethyl esters of vegetable oils are the reliable alternative fuels for the petroleum diesel, because their properties are very nearer to the petroleum diesel. But the flash point and auto-ignition temperatures are very high for these esters. CR （compression ratio） is one of the parameter which influences the atomization and vaporization of fuel. It is also caused for improvement in the turbulence which leads to better combustion. In this work the single cylinder diesel engine was tested at different compression ratios i.e. 16.5：1, 17.5：1, 18.5：1, 19：1 with palm kernel methyl ester without modifications. On increasing compression ratio closeness of molecules of air increases and fuel is injected into that air caused for better combustion. The inbuilt oxygen of methyl or ethyl ester will participate in the combustion and causes for reduction of HC and CO. Better compression ratio for an engine with particular fuel provides satisfactory thermal efficiency and less environmental pollution. In the investigations, for palm kernel methyl ester, 18.5：1 compression ratio is preferable on single cylinder Dl-diesel engine.