环形HYLTE喷管耦合段及光腔区流场的数值模拟

参考传热学相关理论,估算燃烧室的传热损耗分数及相应的平衡温度,确定了主喷管的入口参数设置。在此基础上,对环形HYLTE喷管的耦合段及光腔区流场进行3维的数值模拟,给出了F原子质量分数、静温、静压的空间分布,得到了光腔区各支谱线的小信号增益系数变化曲线。将计算结果与实验结果进行比对,光谱测量结果及移动光轴实验证实了计算模型的合理性。     

直排型连续波DF/HF化学激光器气流通道模型中氮作引射气的相变问题

为了研究直排型连续波DF/HF化学激光器的启动特性,建立了一套化学激光器气流通道双喷管小型实验模型。以氮和氦作为引射介质,采用两种面积比的引射喷管,进行了启动实验。实验表明,当以氮作为引射介质,采用大面积比的引射喷管进行实验时,实验数据与1维理论计算结果相差很大。分析认为,该次实验中,在引射喷管内剧烈地膨胀后,部分N2已经发生相变,理论计算采用的1维定常流处理法已经不再适用。计算表明,连续波DF/HF化学激光器中的光腔燃料和副稀释剂He不会发生相变,但当以N2作副稀释剂时,副稀释剂喷管面积比不能过大。     

直排型连续波DF/HF化学激光器气流通道模型中氮作引射气的相变问题

为了研究直排型连续波DF/HF化学激光器的启动特性,建立了一套化学激光器气流通道双喷管小型实验模型。以氮和氦作为引射介质,采用两种面积比的引射喷管,进行了启动实验。实验表明,当以氮作为引射介质,采用大面积比的引射喷管进行实验时,实验数据与1维理论计算结果相差很大。分析认为,该次实验中,在引射喷管内剧烈地膨胀后,部分N2已经发生相变,理论计算采用的1维定常流处理法已经不再适用。计算表明,连续波DF/HF化学激光器中的光腔燃料和副稀释剂He不会发生相变,但当以N2作副稀释剂时,副稀释剂喷管面积比不能过大。     

高马赫数高压力的氧碘化学激光器阵列喷管的数值模拟

 采用计算流体力学方法,研究了以氮气为载气的新型高总压氧碘化学激光器(COIL)阵列喷管。模拟结果表明:采用高马赫数的氮气流引射低马赫数的氧气流,可以提高光腔出口的驻点压力;高超声速的氮气与声速的氧气混合较慢,在喷管出口安装翼片有利于增强气流混合;喷管出口安装大翼片,翼片诱导的横向涡可以到达氮喷管的中心,光腔内混合比较充分。通过采用10组分21反应的化学反应模型,模拟了阵列喷管内多组分气体的混合和化学反应过程。模拟结果表明：光腔内生成了激发态碘原子和基态碘原子,光腔中获得了正增益,而且光腔出口的总压也由2.6 kPa提升至28.9 kPa。     

高马赫数高压力的氧碘化学激光器阵列喷管的数值模拟

采用计算流体力学方法,研究了以氮气为载气的新型高总压氧碘化学激光器(COIL)阵列喷管。模拟结果表明:采用高马赫数的氮气流引射低马赫数的氧气流,可以提高光腔出口的驻点压力;高超声速的氮气与声速的氧气混合较慢,在喷管出口安装翼片有利于增强气流混合;喷管出口安装大翼片,翼片诱导的横向涡可以到达氮喷管的中心,光腔内混合比较充分。通过采用10组分21反应的化学反应模型,模拟了阵列喷管内多组分气体的混合和化学反应过程。模拟结果表明：光腔内生成了激发态碘原子和基态碘原子,光腔中获得了正增益,而且光腔出口的总压也由2.6 kPa提升至28.9 kPa。     

基于响应面模型的高超声速低温喷管优化

 建立了高超声速低温(HYLTE)喷管的响应面模型,样本点设计矩阵采用正交试验设计法构造,样本数据通过3维粘性NS方程计算喷管光腔耦合段的多组分混合流场获得。基于HYLTE喷管响应面模型,对喷管进行了多目标优化,定义了综合性能参数,优化后喷管混合性能显著改善,综合性能明显提高。计算表明,基于响应面模型的优化策略,能够满足喷管优化对计算精度和计算量的要求。运用多学科设计优化软件框架iSIGHT作为建模和优化的辅助工具,提高了优化设计的实现效率。     

氟化氢泛频化学激光器高超音速低温喷管研究

 通过建立一套氟化氢泛频化学激光器实验系统，介绍了一种新型高超音速低温喷管的结构及其实验参数设置方法；对喷管性能进行了测试，并将实验结果同数值模拟结果进行对比，找出了改善喷管性能的方法。由该喷管构成的激光系统已顺利出光。     

无缓冲气COIL扩压器流场数值模拟

 以无缓冲气化学氧碘激光器(COIL)实验器件的数据计算得到的混合喷管出口参数平均值作为光腔入口条件,对6种不同构型的扩压器从光腔入口至扩压器出口的流场进行了数值模拟,得出了各流场参数分布;对不同构型扩压器的流场特点、总压恢复性能进行了分析;研究了扩压器出口背压对流场参数的影响。结果表明：对于主流无缓冲气的COIL,等截面扩压器具有较好的压力恢复性能;增大扩压器出口背压可以使扩压器的压力恢复性能提高,然而,较高的背压使激波串向光腔方向移动,从而使光腔流场受到干扰,影响光腔的光束质量。     

超音速化学氧碘激光器光腔扩张角

在超音速化学氧碘激光器的设计中,为了削弱光腔部分的化学反应放热对激光器出光的负面效应,在光腔部分通常加入一扩张角。为了研究这一扩张角对激光器内流场的作用,根据kW级超音速化学氧碘激光器的实验平台,数值模拟了激光器内超音速混合喷管至光腔部分的流动过程,解析了光腔扩张角对内流场的流动参量和化学增益的影响,从维持压强和温度稳定性方面比对分析了不同扩张角度的性能,并探索了喷管高度和扩张角之间的规律。结果表明：此kW级超音速化学氧碘激光器的合理光扩张角度为4.5°。     

超音速化学氧碘激光器光腔扩张角

 在超音速化学氧碘激光器的设计中,为了削弱光腔部分的化学反应放热对激光器出光的负面效应,在光腔部分通常加入一扩张角。为了研究这一扩张角对激光器内流场的作用,根据kW级超音速化学氧碘激光器的实验平台,数值模拟了激光器内超音速混合喷管至光腔部分的流动过程,解析了光腔扩张角对内流场的流动参量和化学增益的影响,从维持压强和温度稳定性方面比对分析了不同扩张角度的性能,并探索了喷管高度和扩张角之间的规律。结果表明：此kW级超音速化学氧碘激光器的合理光扩张角度为4.5°。     

突扩燃烧室湍流预混反应流的数值模拟

对突扩燃烧室这一典型工程燃烧装置内的湍流预混反应流进行了数值模拟。时平均控制方程组的封闭采用k-ε湍流输运模型和EBU-Arhenius湍流反应模型。模拟结果给出了突扩燃烧室内湍流预混反应流的气体时均流场、组分浓度场与温度场的分布。通过数值模拟结果与实验的比较对EBU-Arhenius模型进行了讨论与评价。     

三股互击式喷注器及燃烧室流场的数值模拟

结合旋涡耗散模型及Arrhenius化学反应速率系数来描述燃烧室内的化学反应, 对三股互击式喷注器及燃烧室的冷流场及有反应流场进行了三维的数值模拟研究. 引入螺旋度及混合长度参量分析了三股互击式喷注器的混合机理和混合效果, 获取了燃烧室的关键特征参数, 如总温、总温的空间分布、气流在燃烧室内的驻留时间等. 对燃料组合分别采用F-O-F, O-F-O的喷注器及燃烧室的流场特性进行了比较分析. 对于一定的燃料配比和燃烧室特征长度, 燃料组合采用O-F-O时, 在燃烧室出口的F₂解离度比F-O-F要高出13.5%. 实验证实激光器出光功率提升了17%.     

Nature of convection-stabilized DC arcs in dual-flow nozzlegeometry. II. Optical diagnostics and theory

For pt.I see ibid., vol.18, no.1, p.91-101, 1990. A supersonic flow field with a 5.5-cm-long and ≈2.2-mm-thick cylindrical arc plasma column was observed with a four-mirror Schlieren optical system in dual-flow nozzle geometries. For both the orifice-type nozzle and the two dimensional convergent-divergent nozzle, the arc current was varied from 45 to 110 A. The optical cold-flow-plasma boundary displayed a sharp and laminar character in both nozzles, and a sharply defined, almost-constant-diameter, quiet arc is observed between the nozzles. Downstream of the nozzle throat the arc expands and assumes a conical shape. In this region, the fringe formation inside the arc is still clear, which is an indication of the laminar nature of the plasma. However, the arc boundary is not as distinct. A cooler arc is observed downstream of the nozzle throat. Using the experimentally determined axial static pressure and cold-flow mass flux rate distributions of pt.I and the channel-flow model with constant arc temperature, the energy integral was solved for the arc radius as a function of the axial distance. From this, the arc electric field strength, voltage, resistance, and power were determined, and the total heat transfer was related to the arc power. Good agreement between the calculated values and experimental data was observed     

水平圆管内磁性潜热型功能流体对流换热特性的数值模拟

建立磁场作用下水平圆管内磁性潜热型功能流体对流换热的数学物理模型,分析磁场强度、磁性相变微胶囊体积分数、流体质量流量等因素对流体对流换热的影响.磁场对磁性潜热型功能流体的对流换热具有显著的强化作用,磁场强度愈大强化作用愈明显,强化原因是磁性相变微胶囊受到磁力作用产生扰动.     

连续波DF激光器高腔压运转的数值研究

 对以C₂H₄作燃料、以He作稀释剂的燃烧驱动连续波DF化学激光器进行了模拟计算，着重研究了激光器在高腔压条件下的性能。通过比较两种具有不同喷管家结构的DF化学激光器的高腔压运转下的平均腔压、激射强度、输出耦合功率和化学效率，指出高腔压运转对喷管结构的要求。     

Thermo-physical characteristics during the flow and heat transfer analysis of GO-nanoparticles adjacent to a continuously moving thin needle

Nanofluids have shown significant promise in thermal enhancement of many industrial systems and they have been used extensively in energy applications during recent years. Keeping such applications in mind, the present work exhibits a two-dimensional numerical simulation for the boundary layer flow of Graphene oxide (GO)-nanofluids adjacent to a thin needle along with heat transfer. Influence of heat generation/absorption and viscous dissipation have been included to explore the heat transport analysis. The nanofluid flow is generated due to a continuously moving horizontal thin needle. The non-linear expressions governing the flow and heat transfer analysis are changed into dimensionless form by introducing new dimensionless variables. The novelty of current study is to predict the multiple numerical solutions for dimensionless velocity and temperature fields. Numerical computations and graphical delineations were done with the assistance of MATLAB software. This study explores the impacts of several dimensionless key parameters, like, magnetic parameter, Prandtl number, nanoparticles volume fraction and ratio of needle's velocities on the flow and thermal distributions. The computational results have proved that the fluid temperature enhances for higher values of nanoparticles volume fraction while an opposite is true for velocity distributions. In addition, the computed outcomes revealed that for the case of upper branch solution, significant reduction in skin-friction coefficient is seen for higher magnetic parameter.     

Effects of chemical reaction on combined heat and mass transfer by laminar mixed convection flow from vertical surface with induced magnetic field and radiation

The elevated temperature electromagnetic materials production system in chemical engineering requires increasingly more refined theoretical and computational models for describing multiple, simultaneous thermophysical effects. Motivated by this application, the present paper addresses heat and mass transfer in a chemically reacting laminar mixed convection flow from a vertical sheet with inducedmagnetic field. The governing equations of the flow are solved analytically using a perturbation technique. The influences of various established parameters on the flow, induced magnetic field, and heat and mass transfer are studied graphically in the present analysis. Finally, we also obtained expressions for shear stress, current density and Nusselt number, and discussed the results through tables.     

氩等离子体射流在空气环境中冲击平板层流流动与传热的数值模拟

本文采用组合扩散系数方法处理不同气体组分之间的扩散，对氩等离子体的流射入空气环境并撞击平板时的层流流动和传热进行了数值模拟．这种新的处理混合气体中质量扩散的方法有助于更准确地描述等离子体条件下的组分扩散与能量输运。文中给出了射流中速度、温度及氩质量分数的分布情况，以及基板处热流密度分布的若干典型的数值模拟结果．