共查询到19条相似文献,搜索用时 203 毫秒
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在研究IEC和ISA调节阀选择计算方法的基础上,设计了一个汉化软件包,用计算机选择调节阀流量特性,计算局部阻力损失、调节阀压降、阀阻比、流量系数等,并对相对行程、可调比和允差等进行验算。 相似文献
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研究内燃机燃烧特性问题,为了能更为准确地预测HCCI汽油机缸内燃烧特性和排放特性,提出建立了内燃机缸内工作过程的动网格模型,并对狭缝进行加密.对汽油均质压缩燃烧发动机的燃烧过程和排放物的生成过程进行了仿真分析.利用Fluent软件耦合详细化学反应机理,采用RNG k一ε模型以及化学反应涡耗散概念(EDC)模型,计算了特定条件下缸内的温度与压力的变化过程以及缸内的燃料及碳烟等变化趋势,结果表明:狭缝足产生CO和碳氢化合物的主要来源,在详细化学反应机理基础上应用RNG k一ε和化学反应EDC模型能够较为准确地预测HCCI汽油机缸内燃烧和排放.仿真为实际的设计提供了依据. 相似文献
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针对油水气三相流研究试验平台液体流量调节范围宽、范围度大的问题,提出采用3条主回路与3条旁通回流调节支路来覆盖所有的流量范围,设计了液相系统原理图及管路布置图,对3条旁通回流调节支路中调节阀的计算流量、计算压差及Kv值进行了计算,并对调节阀的开度及实际可调比进行了验算,结果表明选定的调节阀性能满足油水气三相流研究试验的要求。 相似文献
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为提高轿车燃油经济性、动力性以及排放清洁性,必须严格控制发动机电控燃油喷射系统混合气的空燃比,则必须对进气流量进行测量.本文介绍了一种卡门式涡流空气流量计进气阻力小、体积小、重量轻、反应灵敏、压力损失低、脉动气流测量精度高、测量范围广的关键. 相似文献
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为挖掘废气再循环(Exhaust Gas Recirculation,EGR)技术的潜力,分别用热力学第一定律和热力学第二定律分析中等负荷时EGR对某SI缸内直啧发动机的影响.结果表明在中等负荷时,EGR使缸内传热损失和泵气损失减小,燃烧不可逆损失有所增加. 相似文献
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介绍调节阀的控制原理,分析调节阀流量特性对控制系统的影响,结合烟草设备的工艺特性,提出烟草制丝设备上调节阀流量特性选择的原则。 相似文献
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NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model furnace of an industrial boiler utilizing fuel gas. The importance of this problem is mainly due to its relation to the pollutants produced by large boiler furnaces used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NO modeling equations were solved together to present temperature and NO distribution inside the radiation and convection sections of the boiler. The boiler under investigation is a 160 MW, water-tube boiler, gas fired with natural gas and having two vertically aligned burners.The simulation study provided the NO distribution in the combustion chamber and in the exhaust gas at various operating conditions of fuel to air ratio with varying either the fuel or air mass flow rate, inlet air temperature and combustion primary air swirl angle. In particular, the simulation provided more insight on the correlation between the maximum furnace temperature and furnace average temperatures and the thermal NO concentration. The results have shown that the furnace average temperature and NO concentration decrease as the excess air factor λ increases for a given air mass flow rate. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NO concentration at the exit of the boiler at λ = 1.2. As the combustion air temperature increases, furnace temperature increases and the thermal NO concentration increases sharply. The results also show that NO concentration at exit of the boiler exhibits a minimum value at around swirl angle of 45°. 相似文献
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The need to reduce development time whilst simultaneously improving engine performance has motivated this application of optimal control to product development processes for engines and powertrains. The optimisation of the fuel consumption is formulated as a constrained Optimal Control Problem (OCP) and solved using pseudospectral methods, giving the optimum heat release and injection profiles in the presence of cylinder pressure rate and cylinder pressure constraints. The technique is applied to an engine design problem and used to reduce fuel consumption by optimising compression ratio within a cylinder pressure limit, also providing new insights into the combustion processes. 相似文献
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Simple adaptive air-fuel ratio control of a port injection SI engine with a cylinder pressure sensor
The problem of air-fuel ratio(AFR) control of the port injection spark ignition(SI) engine is still of considerable importance because of stringent demands on emission control. In this paper, the static AFR calculation model based on in-cylinder pressure data and on the adaptive AFR control strategy is presented. The model utilises the intake manifold pressure, engine speed, total heat release, and the rapid burn angle, as input variables for the AFR computation. The combustion parameters, total heat release,and rapid burn angle, are calculated from in-cylinder pressure data. This proposed AFR model can be applied to the virtual lambda sensor for the feedback control system. In practical applications, simple adaptive control(SAC) is applied in conjunction with the AFR model for port-injected fuel control. The experimental results show that the proposed model can estimate the AFR, and the accuracy of the estimated value is applicable to the feedback control system. Additionally, the adaptive controller with the AFR model can be applied to regulate the AFR of the port injection SI engine. 相似文献
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The polytropic volume method to detect engine events based on the measured cylinder pressure 总被引:1,自引:0,他引:1
T. ThurnheerP. Soltic 《Control Engineering Practice》2012,20(3):293-299
Internal combustion engines deliver work using an intermittent thermodynamic process. For control and diagnosis purposes, it is useful to detect key events relative to the crank angle position. A new method to detect the intake valve closing (IVC), start of combustion (SOC), end of combustion (EOC) or exhaust valve opening (EVO), using the measured cylinder pressure as input, is described. The method is based on the observation that the compression and expansion processes are of polytropic nature. It is shown that the events can be detected by detecting the points where the real and the polytropic volume diverge. 相似文献
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Liangbin Zhang Taixiong Zheng Ying Ma Yongfu Li Ji He 《Asian journal of control》2023,25(2):1115-1129
Homogeneous Charge Compression Ignition (HCCI) combines the characteristics of gasoline engine and diesel engine with high thermal efficiency and low emissions. However, since there is no direct initiator of combustion, it is difficult to control the combustion timing in HCCI engines under complex working conditions. In this paper, Neural Network Predictive Control (NNPC) for combustion timing of the HCCI engine is designed and implemented. First, the black box model based on Elman neural network is designed and developed to estimate the combustion timing. The fuel equivalence ratio, intake valve closing timing, intake manifold temperature, intake manifold gas pressure, and engine speed are chosen as the system inputs. Then, a NNPC controller is designed to control combustion timing by controlling the intake valve closing timing. Simulation results show that the Elman neural network black box model is capable of estimating the HCCI engine combustion timing. In addition, regardless of whether the HCCI engine is in constant or complex condition, the designed NNPC controller is capable of keeping the combustion timing within the ideal range. In particular, under New European Driving Cycle (NEDC) working conditions, the maximum overshoot of the controller is 28.95% and the average error is 1.03 crank angle degree. It is concluded that the controller has good adaptability and robustness. 相似文献
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The present paper addresses the optimal heat release (HR) law in a single cylinder engine operated under reactivity controlled compression ignition (RCCI) combustion mode to minimise the indicated specific fuel consumption (ISFC) subject to different constraints including pressure related limits (maximum cylinder pressure and maximum cylinder pressure gradient). With this aim, a 0-dimensional (0D) engine combustion model has been identified with experimental data. Then, the optimal control problem of minimising the ISFC of the engine at different operating conditions of the engine operating map has been stated and analytically solved. To evaluate the method viability a data-driven model is developed to obtain the control actions (gasoline fraction) leading to the calculated optimal HR, more precisely to the optimal ratio between premixed and diffusive combustion. The experimental results obtained with such controls and the differences with the optimal HR are finally explained and discussed. 相似文献
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This work presents a method to analyze combustion events in an internal combustion engine, called the torque ratio concept. The method is based on crankshaft torque measurements, but an extension to angular speed measurements is possible. The torque ratio concept provides a parametrized model for the combustion progress from which, e.g. combustion phasing can be extracted. The torque ratio concept is derived mathematically and related theoretically to other combustion analysis methods, such as pressure ratio and net heat release. Finally, analysis on recorded data from a five cylinder spark ignited engine verifies the relationships between the three methods. For combustion phasing, the 50% torque ratio is an equivalent measure to 50% pressure ratio and can be transformed into the 50% net heat release position by using a derived volume ratio function. 相似文献
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Jai Prakash Narain 《Computers & Fluids》1977,5(2):61-71
The flow field, temperature field and the heat transfer rates in cylindrical shrouded cavities with rotation, recirculation and coolant through-flow have been analyzed numerically. Two cavity configurations are considered. In the first configuration, a heated cylindrical shroud is enclosed by a stationary insulated stator disc and a rotating insulated rotor disc. The coolant air enters the cavity by a central opening in the rotor and exits through an annular gap at the rim of the rotor. The second configuration studies the heat transfer from an air cooled gas turbine disc using the model of a plane disc rotating close to an insulated shrouded stator. The coolant enters centrally through the stator disc and exits radially through a gap between the shroud and the rotor. The flow field and heat transfer rates are computed for several values of coolant flow rate, the rotor swirl speed, the cavity aspect ratio and the exit gap width in the two cavity configurations. The swirl of the rotor changes immensely the flow pattern, recirculating zones and isotherms inside such cavities. In general, increasing coolant flow rate, decreasing swirl and decreasing aspect ratio enhances the heat transfer from the shroud in the first cavity configuration. For the second cavity configuration, the heat transfer rates increase with increasing coolant flow rate, increasing swirl of the rotor, increasing size of the cavity and decreasing exit gap width between the stator and the rotor. 相似文献
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基于PIV的旋流杯油雾速度场测量研究 总被引:1,自引:0,他引:1
尝试采用粒子图像测速仪(PIV,particle image velocity)对旋流杯出口油雾速度场进行测量,并研究了激光强度和油雾粒径分布对测量结果的影响.结果表明,激光强度对油雾速度场结构无明显影响,但在旋流杯出口射流主体处速度值有一定差异,这是由于产生的激光亮斑超出了相机的动态范围造成的.此外,当旋流杯出口油雾粒径分布较为均匀时,PIV测量油雾速度值与PDPA测得的速度值较为接近,误差在8%左右,该误差对于研究油雾速度场结构及其变化规律是可以接受的,这在一定程度上拓展了PIV的应用领域,提高了油雾速度场的试验效率. 相似文献