Effects of total pressures and equivalence ratios on kerosene/air rotating detonation engines using a paralleling CE/SE method

In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.

Design and application of an air-cooled probe for total pressure measurement at combustor outlet

An air-cooled probe was designed for measurement of total pressure at combustor outlet;its cooling scheme combined the film cooling and convection cooling.With the aid of CFD technique,cooling effectiveness of the coolant jets at various blow ratios was compared;suitable blow ratios and configuration of film holes were chosen accordingly.The overall cooling performance of the probe was evaluated via CFD technique,the design was improved according to the simulation result,and the cooling effect of the leading edge was obviously strengthened by increasing the local coolant mass flow rate.The results of wind tunnel test indicated that,between Mach numbers 0.2 and 0.4,the probe achieved a high accuracy at various attack angles.The probe was utilized in an annular combustor rig test,the highest temperature reached 1 760 Kand total pressure reaches 1 036 kPa.The result of rig test demonstrates that the coolant film distribution consistent appropriately with the CFD results.

Effects of Gamma-Ray Irradiation on Dielectric Surface Breakdown of Polybutylene Naphthalate and Polybutylene Terephthalate Under Reduced Pressure

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

Probe design for measuring total temperature of combustor outlet based on water cooling

To obtain the outlet temperature of combustor,a kind of high-temperature and water cooling thermocouple was designed.The main factors affecting the results of thermocouple measurement were analyzed after numerical simulation.Results showed that the high-temperature water cooling thermocouple can achieve high temperature measurement under the condition of 2 400 K.With the increase of the distance between the water cooling structure and the stagnation cover,the temperature measurement result was more accurate,and the increase in the area ratio of the inlet and outlet of the stagnation cover within a reasonable range can make the measurement results more accurate.The surface emissivity of the measuring point had a great influence on the radiation error.The pressure and flow rate of cooling water can be effectively reduced after adding zirconia coating onto the surface of the rake body.

Relating Fish Hg to Variations in Sediment Hg, Climate and Atmospheric Deposition

This article addresses total fish Hg concentrations (THg) by variations in lake Sediment THg, atmospheric Hg deposition (atmHgdep), and climate, i.e., mean annual precipitation (ppt) and air temperature. The Fish THg data were taken from the 1967-to-2010 Fish Mercury Datalayer (FIMDAC). This compilation was standardized for 12-cm long Yellow Perch in accordance with the USGS National Descriptive Model for Mercury in Fish (NDMMF [1]), and documents Fish THg across 1936 non-contaminated lakes in Canada. About 40% of the standardized Fish THg variations related positively to increasing ppt and Sediment THg, but negatively to increasing mean annual July temperature (TJuly). Only 20% of the Fish THg variations related positively to atmHgdep alone. Increasing TJuly likely influences Fish Hg through increased lake and upslope Hg volatilization, in-fish growth dilution, and temperature-induced demethylization. FIMDAC Fish THg effectively did not change over time while atmHgdep decreased. Similarly, the above Fish Hg trends would likely not change much based on projecting the above observations into the future using current 2070 climate-change projections across Canada and the continental US. Regionally, the projected changes in Fish Hg would mostly increase with increasing ppt. Additional not-yet mapped increases are expected to occur in subarctic regions subject to increasing permafrost decline. Locally, Fish THg would continue to be affected by upwind and upslope pollution sources, and by lake-by-lake changes in water aeration and rates of lake-water inversions.

基于总温探针的高精度总焓测量方法优化研究

为提高中低焓来流的总焓测量精准度,以铱铑铱热电偶为测温元件研制了一种总温探针。基于流热耦合计算模型对该探针各部件尺寸参数进行了优化设计,使得总温探针的复温率不低于0.9;计算和试验结果表明铱铑铱热电偶结点温度会随着热电偶后端面温度和屏蔽罩温度的升高而缓慢升高,导致不同测量时间段下得到的总温值不同,因此必须规定测量时间段并进行溯源校准。为此,借助一种新设计的加热器弧室总温探针,将应用于电弧风洞超声速流场的总温探针向亚声速流场总温校准装置进行了溯源校准。在电弧风洞中开展了总焓测量验证试验,采用基于精度极限和偏差极限的不确定度评估方法,计算了总焓测量结果的不确定度。结果表明:所研制的总温探针具有较高的总焓测量精准度,就本文试验结果而言,其重复性精度约为3%,不确定度约为6.4%。

真空预冷对采后娃娃菜流通及货架品质的影响

为优选娃娃菜真空预冷的处理条件,维持采后娃娃菜的新鲜品质,在分析不同真空预冷终温(0、2和4℃)和不同真空预冷终压(400、600、800和1000 Pa)对采后娃娃菜预冷效果的基础上,进行了二因素三水平的中心复合响应面试验。结果显示,与不经预冷处理的对照和终温0℃的预冷组相比,在终压600 Pa条件下,2~4℃的预冷终温处理可更好地维持采后娃娃菜的外观品质,抑制其呼吸速率和丙二醛(MDA)含量的升高。在终温2℃条件下,与不经预冷处理的对照和终压1000 Pa的预冷组相比,400~800 Pa的预冷终压处理可更好地维持采后娃娃菜的外观品质,抑制其呼吸速率及MDA含量的升高。进一步的中心复合响应面试验结果显示,采后娃娃菜的真空预冷最优条件为终温4.0℃、终压600 Pa,该真空预冷条件不仅可维持采后娃娃菜的较好品质,而且可使活性物质可溶性蛋白、总酚和抗坏血酸的含量分别提高18.78%、18.47%和33.23%。因此,适宜的真空预冷处理是一种极具潜力的商品化处理技术,能有效维持采后娃娃菜在流通及货架期间的良好品质。

不同负荷工况下660 MW循环流化床锅炉脱硝特性研究

为揭示不同负荷下循环流化床的运行特性,以某660 MW循环流化床锅炉为研究对象,在满负荷、75%负荷下,具体研究床温波动、风量配比、烟气含氧量和风煤配比对选择性非催化还原(selective non-catalytic reduction,SNCR)技术喷氨量和脱硝效果的影响。结果表明:满负荷运行时,在欠氧区,SNCR投射喷氨量与循环流化床锅炉给煤量保持同向变化趋势,若持续提高喷氨量,会导致氨逃逸较大,降低SNCR脱硝能力;当炉内给煤量保持稳定,在欠氧还原区内,适当提高二次风量(含氧量),会促进挥发分N的还原反应。75%负荷运行时,床温波动范围超过110℃时,为了满足脱硝要求,应适当提高一次风量、降低二次风量和喷氨量;床温波动范围低于50℃时,应适当降低一次风量和喷氨量;床温波动范围在50~100℃时,应适当降低二次风量和喷氨量;欠氧区内,喷氨量随总给煤量增多而增大。研究结果可以指导循环流化床优化运行,减少氮氧化物排放。

总温总压组合式受感器设计

由于一般总温传感器体积大、功能单一,不能适应小型飞行器安装使用,因此设计了一种小型总温总压组合式受感器。其中,对受感器外形结构、屏蔽罩、密封结构等进行设计,并设计一种温度压力一体式敏感组件,采用玻璃烧结工艺解决敏感组件的耐高温、密封、绝缘等关键技术。通过Fluent流体仿真软件对受感器流场进行模拟仿真,分析引压管对受感器内部流场的影响,结合仿真结果对受感器进行优化设计。经风洞试验校准,在Ma=0.3至Ma=0.9范围内,受感器总温恢复系数≥0.970;Ma=0.3(高度H=0)条件下,受感器时间常数小于0.9 s。1 MPa压力条件下进行气密性测试,1 min内压力下降不超过300 Pa;在Ma=0.3至Ma=1.0范围内总压误差优于±0.02,达到较高的技术指标要求。

Experimental study on pressure and temperature distributions for low mass flux steam jet in subcooled water

A low mass flux steam jet in subcooled water was experimentally investigated.The transition of flow pattern from stable jet to condensation oscillation was observed at relatively high water temperature.The axial total pressures,the axial and radial temperature distributions were measured in the jet region.The results indicated that the pressure and temperature distributions were mainly influenced by the water temperature.The correlations corrected with water temperature were given to predict the dimen-sionless axial pressure peak distance and axial temperature distributions in the jet region,the results showed a good agreement between the predictions and experiments.Moreover,the self-similarity property of the radial temperature was obtained,which agreed well with Gauss distribution.In present work,all the dimensionless properties were mainly dependent on the water temperature but weakly on the nozzle size under a certain steam mass flux.

月均气温对三叶青林下容器栽培苗光合特性及其块根总黄酮含量的影响

文章比较了2015—2019年五府山月均气温对三叶青林下容器栽培苗光合生理及其块根总黄酮含量的影响。结果表明,2015—2019年,五府山1月的气温最低,2—6月气温逐渐提升,7—8月气温达到最高值,9—12月气温逐渐下降。随着1—6月气温逐渐提高,五府山三叶青林下容器栽培苗叶绿素含量SPAD值、净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))、气孔限制值(L_(s))、瞬时羧化速率(CUE)、初始荧光(F_(o))、最大荧光(F_(m))、光下最小荧光(F′_(o))、光下最大荧光(F′_(m))、稳态荧光(F_(s))、PSⅡ最大光能转化效率(F_(v)/F_(m))、PSⅡ潜在光化学效率(F_(v)/F_(o))、PSⅡ实际光化学效率(ΦPSⅡ)、开放的PSⅡ反应中心捕获激发能效率(F′_(v)/F′_(m))、光化学淬灭系数(q P)和块根总黄酮含量显著提高(P<0.05),胞间CO 2浓度(C_(i))、水分利用效率(WUE)和非光化学淬灭系数(NPQ)显著下降(P<0.05);气温在7—8月达到最高值,五府山三叶青林下容器栽培苗叶绿素含量SPAD值、P_(n)、G_(s)、T_(r)、L_(s)、CUE、F_(o)、F_(m)、F′_(o)、F′_(m)、F_(s)、F_(v)/F_(m)、F_(v)/F_(o)、ΦPSⅡ、F′_(v)/F′_(m)、q P和块根总黄酮含量达到最大值,C_(i)、WUE和NPQ达到最低值;9—12月气温逐渐下降,五府山三叶青林下容器栽培苗叶绿素含量SPAD值、P_(n)、G_(s)、T_(r)、L_(s)、CUE、F_(o)、F_(m)、F′_(o)、F′_(m)、F_(s)、F_(v)/F_(m)、F_(v)/F_(o)、ΦPSⅡ、F′_(v)/F′_(m)、q P和块根总黄酮含量显著下降(P<0.05),C_(i)、WUE和NPQ显著提高(P<0.05)。本试验结果可为三叶青林下容器生态栽培提供气象因子(气温)依据。

双洞隧道单斜井多掌子面风仓气动性能优化设计

为解决传统管道式通风在长大隧道大角度弯折处有较大局部阻力与风力损失的弊端,以西十高铁西岭隧道3#斜井为工程背景,提出风仓式通风方案,确定风仓接力轴流风机工作流量。采用控制变量法,以风仓进出风口、全压和风仓内风流平顺度为设计目标,以风仓隔板长度、风仓进出口位置为设计变量,基于Box-Behnken试验设计,进行风仓气动性能数值计算,得到各参数对风仓气动性能的影响顺序,最终确定风仓最优尺寸参数组合。研究结果表明:优化后风仓2个出口全压值基本相等,风机协调性好,风流场较均匀稳定,可有效缓解风仓内涡团现象。

压气机试验用典型结构探针吹风试验研究

围绕压气机气动性能试验中探针测量准确性问题,对压气机试验用典型结构的总压探针(滞止罩结构和球窝结构)、总温探针(单屏蔽结构和多屏蔽结构)开展了对比吹风试验研究。研究表明,滞止罩结构总压探针在气流不敏感角、测量精度、测量稳定性等方面均优于球窝结构总压探针,单屏蔽热电偶总温探针的总温恢复特性优于双屏蔽总温探针。当温度较低时,热辐射误差的影响较小,双屏蔽总温探针在总温测量精度方面较单屏蔽探针未体现出明显优势。

高温强余旋来流条件下一体化加力燃烧室流场特性的数值研究

为发展高温强余旋进气条件下一体化加力燃烧室性能优化方法,开展了不同结构参数变化对一体化加力燃烧室流场特性影响规律的数值模拟研究。结果表明:(1)扩压器长度过短容易导致流动分离,使总压恢复系数和燃烧效率降低,扩压器长度过长则会影响强余旋来流与整流支板的匹配性;(2)增加扩压器面积比,可以有效提升支板后回流区稳火性能、燃烧效率及总压恢复系数;(3)支板长度过短或过长,均会降低总压恢复系数和凹腔-中心锥一体化回流区的稳火性能;(4)增加支板宽度,可以有效提高燃烧效率与稳火性能;(5)增加支板尾缘扩张角,可以有效提高支板后回流区的稳火性能。

某型F级轴向分级燃烧室的全温全压试验研究

在全温全压条件下对自主研发的F级燃气轮机轴向分级燃烧室进行了燃烧试验研究,以探究设计点工况下燃烧室的压力损失、出口温度分布、火焰筒壁面温度、污染物排放、燃烧效率和热声稳定性等燃烧性能。结果表明:在设计点工况下,燃烧室总压损失系数为5.4%;燃烧室出口温度分布系数为0.06,燃烧室出口径向温度分布系数为0.03;燃烧室火焰筒壁面温度低于850℃;NO_(x)摩尔分数维持在1.9×10^(-5),CO和未燃碳氢(UHC)排放基本为0,燃烧效率维持在99.99%以上;压力脉动各特征频率对应幅值均低于3 kPa,表明燃烧室热声状态稳定。

低速大迎角进气道流场测试风洞试验研究

为满足某型飞机低速大迎角飞行试验进气道测试需求,研制集稳态总压、动态总压、稳态静压于一体的复合式进气道流场测量耙,为了分析评估不同形式测量耙探针的参数测量准确性,进行全尺寸的测量耙风洞试验,对试验数据进行分析,研究测量耙不同探针总压损失的角度特性和速度特性,为后续测量耙探针选型提供支持。

外界因素对玻璃钢制品TVOC释放变化的影响研究

以家具行业中广泛使用的玻璃钢制品为研究对象,利用环境舱法探究了其TVOC(总挥发性有机化合物)释放速率随时间、温度、相对湿度和气体交换率变化的释放规律。结果表明,玻璃钢制品中TVOC释放速率随时间变化符合一阶衰减模型,相关性良好;同时,提高温度、相对湿度和气体交换率可加速玻璃钢制品中TVOC的释放,释放初期影响显著,后期影响减弱。此外,针对玻璃钢制品的经济实用处理措施为:短时间增温、增湿、增大气体交换率的烘烤通风后,室外继续通风凉放15 d时间,这为提升玻璃钢制品环保性能提供了可靠参考数据。

螺旋桨滑流对涡轮螺旋桨进气道气动性能影响仿真研究

基于计算流体动力学方法,对螺旋桨滑流对涡轮螺旋桨飞机发动机进气道性能的影响进行仿真分析。使用多重参考系方法模拟螺旋桨滑流效应,分别在设计状态点和非设计状态点下分析了有、无滑流对进气道主流道性能的影响。结果显示:设计状态点有滑流状态与无滑流状态相比,总压恢复系数和总压畸变指数均有增大,地面状态下总压恢复系数增大了约3%,总压畸变指数增大0.0823~0.0980;高空状态下总压恢复系数增大了约2%,总压畸变指数增大0.0737~0.1048。非设计状态点随来流马赫数的增大,总压恢复系数和总压畸变指数逐渐减小。

水中总磷测定不同前处理方法的适宜性研究

为了快速准确地测定水中总磷,采用硝酸-过硫酸钾微波消解、过硫酸钾高温高压消解及硝酸-高氯酸电热板消解3种方法分别对不同类型水样进行前处理,测定总磷含量。研究结果表明:测定地表水中总磷,3种前处理方法均适宜。对生活污水入口及工业废水入口样品,适合选用硝酸-过硫酸钾微波消解方法;对生活污水出口及工业废水出口样品,适合选用硝酸-过硫酸钾微波消解和过硫酸钾高温高压消解方法。

马钢1#高炉炉况波动处理生产实践

针对马钢1#高炉炉芯温度持续下降,高炉全压差水平偏高,对炉况进行调整过程中,炉况出现大幅波动,进行干湿焦转换后炉况下滑严重,气流周向分布不匀,炉缸活跃性持续下降。为解决炉墙周向气流分布不均匀,改善炉缸工作状态,采用锰矿及萤石进行洗炉等恢复炉况,炉况好转后,逐步捅开长堵风口恢复炉况,风量、氧量恢复至4 900 m^(3)/min、9 000 m^(3)/h,负荷4.3,产量6 200 t/d,此次炉况波动,因后续采取的措施及时果断,炉况恶化趋势得到有效遏制并恢复。