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1.
The combustion performance of hydrogen fuel in a scramjet combustor has been a popular focus for scholars all over the world. In this study, the influence of the jet-to-crossflow pressure ratio on combustion performance in a scramjet combustor was investigated numerically, and the influence of a wall-mounted cavity was evaluated. The simulations were conducted using the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) k-ε turbulence model and the single-step chemical reaction mechanism. This numerical approach was validated by comparing predicted results with published experimental shadowgraphs and velocity and temperature measurements. When the pressure of the wall-injector increases, the performance of the combustor decreases. At the same inflow condition, this may lead to a scram-to-ram mode transition. The cavity adopted in this study would prevent pre-combustion shock waves from pushing out of the isolator and help to stabilize the flow field, but it would decrease the mixing and combustion efficiencies.  相似文献   

2.
The transverse injection flow field has an important impact on the flowpath design of scramjet engines. At present a combination of the transverse injection scheme and any other flame holder has been widely employed in hypersonic propulsion systems to promote the mixing process between the fuel and the supersonic freestream; combustion efficiency has been improved thereby, as well as engine thrust. Research on mixing techniques for the transverse injection flow field is summarized from four aspects, namely the jet-to-crossflow pressure ratio, the geometric configuration of the injection port, the number of injection ports, and the injection angle. In conclusion, urgent investigations of mixing techniques of the transverse injection flow field are pro- posed, especiaUy data mining in the quantitative analytical results for transverse injection flow field, based on results from multi-objective design optimization theory.  相似文献   

3.
设计制造了工业燃烧技术和加热炉技术的教学实验与科研装置,主要包括水套加热炉、燃油及燃气全自动燃烧机、烟气分析仪等。由全自动燃烧机为水套炉提供热源,通过燃烧室外侧水套及管式换热器,将热量传递给循环水,出口烟气温度为70~150℃;利用穿过水套的测量孔,测量燃烧室的温度场、速度场、浓度场,在烟道出口测定烟气成分。利用该装置能够进行科学全面的燃烧技术的研究和评价,并已在教学实验中取得了很好的教学效果。  相似文献   

4.
超高温多相流燃烧研究在快速飞行的航天飞行器应用领域中至关重要。本文依据固体火箭发动机喷焰超音速射流燃烧中产生大量的氧化铝固体颗粒群和多组分气体实际应用为背景,结合粒子浓度的实际特征,建立固体颗粒群粒子浓度分布模型,并根据粒子质量加权平均直径经验公式,计算它们在波长3～5!m范围内的空间红外辐射强度随温度场的分布。同时对燃烧过程中产生的几种多组分接近完全气体,计算其热传导系数,为进一步开展相关红外特性研究和建立用于超高温多相燃烧红外辐射理论模型提供重要依据。  相似文献   

5.
以“统一模型”为理论基础,利用高速摄影机,对掺与不掺 Ｃａ＋＋之高氨酸铵（ＡＰ）晶体在带透明窗燃速仪中的爆燃进行了观测、分析,并初步讨论了Ｃａ＋＋的掺入对ＡＰ凝相反应的作用机理．研究表明,Ｃａ＋＋的掺入使ＡＰ晶体在固体火箭发动机经常工作的压强范围内压强指数降低,并在某一压强区段（实验中为７～８．５ＭＰａ）压强指数出现负值,这为进一步完善“统一模型”提供了依据,为负压强指数推进剂的研制和进一步降低硝胺／ＡＰ复合推进剂的压强指数提供了新的途径．  相似文献   

6.
液体燃料小尺度扩散火焰影响因素分析   总被引：2，自引：0，他引：2  
针对乙醇液体燃料小尺度层流扩散燃烧的影响因素进行了分析。影响因素包括燃料流量、喷管口径、外加电场的电压大小、电极距等等,并且定性分析散热损失对燃烧火焰的影响,为微小尺度燃烧器的设计提供了一定的参考。  相似文献   

7.
ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅｗｏｒｌｄｆａｃｉｎｇｓｅｒｉｏｕｓｐｏｌｌｕｔｉｏｎｏｆｅｎ ｖｉｒｏｎｍｅｎｔａｎｄｉｎｅｖｉｔａｂｌｅｄｅｃｌｉｎｉｎｇｒｅｓｏｕｒｃｅｓｏｆｅｎｅｒｇｙ,ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｌｏｗｅｒｐｏｌｌｕｔｉｏｎａｎｄｌｏｗｅｒｅｎｅｒｇｙｃｏｎｓｕｍｐｔｉｏｎａｕｔｏｍｏｂｉｌｅｈａｓｂｅ ｃｏｍｅａｍａｊｏｒｒｅｓｅａｒｃｈｔａｒｇｅｔ.Ｔｈｅｈｉｇｈｅｆｆｉｃｉｅｎ ｃｙａｎｄｌｏｗｐｏｌｌｕｔｉｏｎｎａｔｕｒａｌｇａｓ ｄｉｅｓｅｌｄｕａｌｆｕｅ…  相似文献   

8.
Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements.  相似文献   

9.
Gas flows and particle mass flux were measured and clutriation experimentswere conducted in two cold test models of vortexing fluidized bed(VFB).The experimen-tal results show that the secondary air injected tangentially creates strong vortexes,estab-lishes particle suspension layers and internal circulation,and suppresses the elutriation offine particles greatly.The vortexing fluidized bed combustion has bright prospect bccauseof its much higher combustion efficiency and desulphidation efficiency than bubblingfluidized bed combustion due to long particle residence time and high slip velocity betweengas and solid,and its simpler configuration and lower cost than circulating fluidized bedcombustion.  相似文献   

10.
In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine. Project supported by National Lab. for Automotive Engine and Safety, Tsinghua University, China  相似文献   

11.
NomenclatureA-area ( m2)Dw-membrane water diffusivity ( m2/s)F-=96 487I-current (A)M-molecule mass (kg/mol)T-temperature (K)W-mass flowrate (kg/s)cw-water concentration in membrane ( mol/m3)m-mass (kg)n-cell numbernd-electro-osmotic drag coefficientp-pres…  相似文献   

12.
This paper describes a solar photovoltaic fuel cell (PVEC) hybrid generation system consisting of a photovoltaic (PV) generator, a proton exchange membrane fuel cell (PEMFC), an electrolyser, a supercapacitor, a storage gas tank and power conditioning unit (PCU). The load is supplied from the PV generator with a fuel cell working in parallel. Excess PV energy when available is converted to hydrogen using an electrolyser for later use in the fuel cell. The individual mathematical model for each component is presented. Control strategy for the system is described. MATLAB/Simulink is used for the simulation of this highly nonlinear hybrid energy system. The simulation results are shown in the paper.  相似文献   

13.
模拟了一种常规快速式燃气热水器的燃烧系统,研究了不同压力状况下的燃烧工况.得到的数值模拟结果与实验获得的数据吻合得较好,证明了所用物理模型和数学模型的合理性.结果显示,火焰高度和过剩空气系数依赖于系统出口和入口的静压差,而与燃烧室内的绝对压力无关.该静压差和系统中用于燃烧的空气量显著影响CO的生成,与CO的生成量呈反比关系,并同时影响燃烧区域内的温度场和速度场.为降低CO排放水平,必须增加进入燃烧系统的空气量,因此需要增加风机输出功率以提供足够的空气压头.该研究为设计快速式燃气热水器提供了一种行之有效的方法.  相似文献   

14.
Experimental study on homogeneous charge compression ignition (HCCI) combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether(DME). The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetanc number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays,the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore, to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and beth rise with the increase of the concentration of inert gases.  相似文献   

15.
Control design is important for proton exchange membrane fuel cell （PEMFC） generator. This work researched the anode system ofa 60-kW PEMFC generator. Both anode pressure and humidity must be maintained at ideal levels during steady operation. In view of characteristics and requirements of the system, a hybrid intelligent PID controller is designed specifically based on dynamic simulation. A single neuron PI controller is used for anode humidity by adjusting the water injection to the hydrogen cell. Another incremental PID controller, based on the diagonal recurrent neural network （DRNN） dynamic identification, is used to control anode pressure to be more stable and exact by adjusting the hydrogen flow rate. This control strategy can avoid the coupling problem of the PEMFC and achieve a more adaptive ability. Simulation results showed that the control strategy can maintain both anode humidity and pressure at ideal levels regardless of variable load, nonlinear dynamic and coupling characteristics of the system. This work will give some guides for further control design and applications of the total PEMFC generator.  相似文献   

16.
ＣＯＭＰＲＥＨＥＮＳＩＶＥＳＴＵＤＩＥＳＯＮＣＯＡＬ－ＦＩＲＥＤＭＨＤＣＯＭＢＵＳＴＩＯＮＴＥＣＨＮＩＱＵＥＣｈｅｎｇＹｏｎｇｙｕａｎ（程永元）ＣａｉＳｏｎｇ（蔡崧）（ＴｈｅｒｍｏｅｎｅｒｇｙＥｎｇｉｎｅｅｒｉｎｇＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅ）...  相似文献   

17.
This paper presents a theory on premix fuel combustion at near isoceles triangle type rate of heat release, describes the measures taken for the combustion system, points out its many theoretical advantages, and that it can solve effectively the problems of rough running, fuel consumption and exhaust emission. Two squish lip type combustion chambers are designed to match separately with multiple holes injector and conical spray type injector in order to achieve premix combustion at near isosceles triangle type rate of heat release. Experimental studies on two single cylinder diesel engines showed that premix combustion at isosceles triangle type rate of heat release resulted in longer ignition delay period, larger amount of fuel injected into cylinder during the ignition delay period, lower maximum pressure, better fuel economy, and better exhaust emission.  相似文献   

18.
煤气发生炉是连轧厂最为重要的辅助设备之一,为连轧厂蓄热式加热炉提供高效、清洁的煤气,煤气发生炉的正常运行直接关系着后续的生产;为了实现对煤气发生炉进行有效的控制,设计了基于iFIX组态监控软件的实时监控系统,通过MPI电缆实时采集S7-300PLC的各种信号——煤气温度、汽包压力、饱和温度、鼓风压力等,并实现自动控制,实时显示和超限报警,达到了预期的设计目标。  相似文献   

19.
This paper presents an experimental study on the emission characteristics and combustion instabilities of oxy-fuel combustions in a swirl-stabilized combustor. Different oxygen concentrations （Xoxy=25%-45%, where Xoxy is oxygen concentration by volume）, equivalence ratios （φ=0.75-1.15） and combustion powers （CP= 1.08-2.02 kW） were investigated in the oxy-fuel （CH4/CO2/O2） combustions, and reference cases （Xoxy=25%-35%, CH4/N2/O2 flames） were covered. The results show that the oxygen concentration in the oxidant stream significantly affects the combustion delay in the oxy-fuel flames, and the equivalence ratio has a slight effect, whereas the combustion power shows no impact. The temperature levels of the oxy-fuel flames inside the combustion chamber are much higher （up to 38.7%） than those of the reference cases. Carbon monoxide was vastly produced when Xoxy〉35% or （φ〉0.95 in the oxy-fuel flames, while no nitric oxide was found in the exhaust gases because no N2 participates in the combustion process. The combustion instability of the oxy-fuel combustion is very different from those of the reference cases with similar oxygen content. Oxy-fuel combustions excite strong oscillations in all cases studied Xoxy=25%-45%. However, no pressure fluctuations were detected in the reference cases when Xoxy〉28.6% accomplished by heavily sooting flames which were not found in the oxy-fuel combustions. Spectrum analysis shows that the frequency of dynamic pressure oscillations exhibits randomness in the range of 50-250 Hz, therefore resulting in a very small resultant amplitude. Temporal oscillations are very strong with amplitudes larger than 200 Pa, even short time fast Fourier transform （FFT） analysis （0.08 s） shows that the pressure amplitude can be larger than 40 Pa.  相似文献   

20.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｒｅｓｓｕｒｅｇｒａｐｈｇｉｖｅｎｂｙＬｉｎｉｎ 1 960ｏｆｆｏｕｒｔｙｐｅｓｋｉｎｄｓｏｆｒａｔｅｏｆｈｅａｔｒｅｌｅａｓｅｓｈｏｗｅｄｔｈａｔｔｈｅｉｓｏｓｃｅｌｅｓｔｒｉａｎｇｌｅｔｙｐｅｒａｔｅｏｆｈｅａｔｒｅ ｌｅａｓｅｗａｓｉｄｅａｌｏｎｃｏｎｄｉｔｉｏｎｏｆｔｈｅｓａｍｅｍａｘｉ ｍｕｍｐｒｅｓｓｕｒｅ .Ｔｈｅｃｏｎｃｌｕｓｉｏｎｉｓａｌｓｏｒｅａｃｈｅｄｉｎｔｈｅｒｍｏｄｙｎａｍｉｃｓ.Ｉｔｉｓｐｏｐｕｌａｒｌｙａｃｃｅｐｔｅｄｔｈａｔｔｈｅｌａｒｇｅ…  相似文献   

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