共查询到19条相似文献,搜索用时 206 毫秒
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本文利用CFD技术和SACTI模型对山东某电厂冷却塔附近流场以及冷却塔雾羽抬升以及漂滴与盐的沉积对局地环境影响进行了模拟计算,并与现场试验结果进行对比分析验证。结果表明,二者模拟结果与现场试验数据基本吻合, SACTI模型预测漂滴与盐沉积的最大距离出现在冷却塔附近200 m范围内,CFD技术模拟漂滴与盐沉积的最大距离出现在下风向500 m左右。SACTI模型预测漂滴与盐地面最大沉积量约为CFD技术模拟地面最大沉积量的3倍,主要原因是由于CFD在模拟过程中考虑的冷却塔局地环流以及周围建筑物对漂滴沉积的影响。 相似文献
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随着国内核电厂规模不断扩大和集中,为保护海洋生态环境,滨海核电厂将以大型海水冷却塔二次循环作为主要冷却方式。研究盐沉积的计算方法对海水冷却塔环境影响评价工作具有重要意义。本文采用SACTI程序,建立冷却塔数学模型,以河北海兴核电厂大型海水冷却塔为例,模拟计算飘滴和沉降影响,进而根据循环冷却水含盐量,评价盐沉积的范围和影响。结果显示海水冷却塔的盐沉积不会对该厂址周边植物产生危害。 相似文献
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大型自然通风冷却塔造成的荫屏、太阳辐射损失、水沉积和盐沉积等环境影响已逐渐成为当前国内研究的热点。由于国内目前尚未有已建成的核电厂大型自然通风冷却塔,所以利用预测模型研究大型自然通风冷却塔的环境影响成为当前的一个关注点。首先介绍了美国Argonne国家实验室开发的冷却塔评价模型SACTI的基本原理和结构组成,以江西彭泽核电厂为例,与美国Amos电厂的预测结果进行比较分析,说明了SACTI模型在实际工作中的应用及影响其计算结果的主要因素。结果表明,在缺乏监测数据的情况下,SACTI模型的模拟结果具有重要的参考意义,同时本文的研究成果为深入开展该项研究工作提供了有意义的基础。 相似文献
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利用风洞实验与数值模拟方法研究了某核电厂冷却塔在有无热羽排放情况下,对区域流场及烟羽扩散的影响。包括了受冷却塔及其热羽影响下厂址区域的平均流场及湍流结构,冷却塔热羽对烟羽空中分布、地面轴线浓度及扩散参数的的影响。结果表明:受冷却塔及其热羽影响风向轴线上风速明显减小,出现双速度亏损区。冷却塔热羽使得污染物扩散增强,散布范围增大,最大浓度降低,对垂向扩散影响显著。冷却塔对周围大气流动和污染物扩散的影响程度与烟囱和冷却塔的相对位置密切相关,冷却塔与烟囱连线与风向平行时,受影响尤为显著。同时,冷却塔所排热羽对污染物扩散的影响还与释放源和冷却塔的相对位置有关。 相似文献
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将我国中新生代陆相盆地含铀沉积建造类型划分为陆相暗色(灰色)含煤碎屑沉积建造、陆相红色(杂色)碎屑沉积建造及陆相红色含膏盐沉积建造3类,并概述其沉积特征.探讨了沉积建造研究在砂岩型铀矿科研及生产找矿方面的意义. 相似文献
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本文介绍在核电厂事故应急局地实时剂量评价系统中应用的拉格朗日烟团模式及相应的参数。对烟团轨迹考虑了事故期间风向、风速的变化,采用有效扩散参数以考虑烟团迁移期间大气稳定度等气象条件的变化,干沉积采用源耗减模式,湿沉积采用冲洗系数方法,还考虑了放射性衰变及烟团部分穿透混合层的修正。鉴于我国在建核电厂皆位于沿海地区,文中还给出了内边界层条件下烟团公式的处理方法。对于实时剂量评价,主要考虑了烟云浸没外照射、吸入内照射和沉积放射性核素外照射三种照射途径。最后,以秦山核电厂为例估算了 PWR1事故的环境影响,给出了部分计算结果。 相似文献
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This study presents the Langmuir and Faraday probe measurements conducted to determine the plume characteristics of the BUSTLab microwave electrothermal thruster (MET). The thruster, designed to operate at 2.45 GHz frequency, is run with helium, argon and nitrogen gases as the propellant. For the measurements, the propellant volume flow rate and the delivered microwave power levels are varied. Experiments with nitrogen gas revealed certain operation regimes where a very luminous plume is observed. With the use of in-house-built Langmuir probes and a Faraday probe with guard ring, thruster plume electron temperature, plasma density and ion current density values are measured, and the results are presented. The measurements show that MET thruster plume effects on spacecraft will likely be similar to those of the arcjet plume. It is observed that the measured plume ion flux levels are very low for the high volume flow rates used for the operation of this thruster. 相似文献
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In this work,we investigated the influence of air gas pressures on the expansion features of nanosecond laser ablated aluminum plasma in the absence and presence of a nonuniform magnetic field using fast photography.A particular emphasis was given to the plume dynamics(shape,size) with the combined effects of ambient gas pressures and an external magnetic field.Free expansion,sharpening effect,and hemi-spherical structures of the aluminum plasma were observed without a magnetic field under different gas pressures.Analysis of the resulting plume images with the combined effects of air gas pressures and a magnetic field show significant changes,such as plume splitting,elliptical geometry changes,radial expansion,and plume confinement.Furthermore,the total size of the plasma plume with a magnetic field was measured to be smaller than the plasma plume without a magnetic field at several background pressures. 相似文献
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考虑到在辐射环境评价中使用NRC耗减曲线和沉积曲线时存在的问题,以及流出物粒径分布的影响,本文用国内实测的3种粒径分布粒子的干沉积速度用源耗减模式计算了烟羽残留份额和相对干沉积率,并分别与NRC的结果进行了比较。结果表明,本文计算的3种模态粒子的烟羽残留份额曲线和相对干沉积率曲线与都NRC的结果有明显的差别。在辐射环境评价中要充分考虑流出物的粒径分布,谨慎选择沉积速度。 相似文献
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Xinwei CHEN 《等离子体科学和技术》2022,24(7):74003
The distribution of the thermal effects of the ion thruster plume are essential for estimating the influence of the thruster plume, improving the layout of the spacecraft, and for the thermal shielding of critical sensitive components. In order to obtain the heat flow distribution in the plume of the LIPS-200 xenon ion thruster, an experimental study of the thermal effects of the plume has been conducted in this work, with a total heat flow sensor and a radiant heat flow sensor over an axial distance of 0.5–0.9 m and a thruster angle of 0°–60°. Combined with a Faraday probe and a retarding potential analyzer, the thermal accommodation coefficient of the sensor surface in the plume is available. The results of the experiment show that the xenon ion thruster plume heat flow is mainly concentrated within a range of 15°. The total and radial heat flow of the plume downstream of the thruster gradually decreases along the axial and radial directions, with the corresponding values of 11.78 kW m−2 and 0.3 kW m−2 for the axial 0.5 m position, respectively. At the same position, the radiation heat flow accounts for a very small part of the total heat flow, approximately 3%–5%. The thermal accommodation factor is 0.72–0.99 over the measured region. Furthermore, the PIC and DSMC methods based on the Maxwell thermal accommodation coefficient model (EX-PWS) show a maximum error of 28.6% between simulation and experiment for LIPS-200 ion thruster plume heat flow, which, on the one hand, provides an experimental basis for studying the interaction between the ion thruster and the spacecraft, and on the other hand provides optimization of the ion thruster plume simulation model. 相似文献
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通过测定脉冲紫外激光在氦气中烧蚀金属Cu诱导发光羽的发射光谱及其强度随时间的分布,拍摄了发光羽的照片。实验结果表明:在低压下,发光羽的中心区与中间层均为混合色,外围层为黄绿色;中压下,发光羽的中心区和中间层均为白色,外围层为淡绿色;高压下,发光羽的中心区和中间层均为白色,外围层为微绿色。发光羽区域随着环境气压的增大而减小,其颜色随环境气压的增大而变淡。结合实验结果,对发光羽的发光机理进行了探讨。中压及低压下以电子与原子、离子的碰撞传能激发以及原子与原子、离子的碰撞传能激发为主要机理;高压下以电子韧致辐射及电子与离子的复合激发为主要机理。并用此机理定性地解释了所观察到的实验现象。 相似文献
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In this study,a laser-assisted pulsed plasma thruster (LA-PPT) with a novel configuration is proposed as an electric propulsion thruster which separates laser ablation and electromagnetic acceleration.Owing to the unique structure of the thruster,metals can also be used as propellants,and a higher specific impulse is expected.The ablation quality,morphology,and plume distribution of various metals (aluminium alloy,red copper,and carbon steel) with different laser energies were studied experimentally.The ablation morphology and plume distribution of red copper were more uniform,as compared to those of other metals,and the ablation quality was higher,indicating its greater suitability for LA-PPT.The plume generated by nanosecond laser ablation of aluminium alloy expanded faster,which indicated that the response time of the thruster with aluminium alloy as the propellant was shorter.In addition,when the background pressure was 0.005 Pa,an obvious plume splitting phenomenon was observed in the ablation plume of the pulsed laser irradiating aluminium alloy,which may significantly reduce the utilisation rate of the propellant. 相似文献
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