鱼雷罐斜插式喷吹脱硫水模试验研究

通过水力学模型试验,分析了鱼雷罐斜插式喷吹脱硫过程中熔池内的流动状态,研究了熔池不同区域之间动力学条件的差异以及工艺参数对熔池混匀时间的影响规律.结果表明：斜插式喷吹脱硫工艺中,喷吹气体的上浮状态仍然呈垂直向上形态,但熔池内液体的循环运动呈现明显的不对称形;鱼雷罐两侧端部死区的脱硫动力学条件差别较大,导致两区域铁水脱硫效果不同,容易引起铁水回硫;试验条件下,随着喷吹气体流量和喷枪插入深度的增大,喷吹气体搅拌动能的增加,熔池内液体的整体混匀时间逐渐减小.     

侧底复吹RH真空精炼中均混特性的物理模型研究

基于相似原理,建立了几何相似比为1：5的水模型,对RH精炼过程钢液循环流动行为进行研究。考察了提升气体流量、真空度、不同吹气方式以及不同形状的浸渍管对混匀时间的影响规律。结果表明：均混时间随吹气量增大先减小后增大,随真空度增大而减小。在相同吹气流量下,单独采用侧底复吹方式或单独采用椭圆形浸渍管,均混时间减小。     

Unsteady numerical investigation of back‐step three‐dimensional slots on film cooling effectiveness

A numerical investigation was carried out to study the aerodynamics and cooling effects of a trailing edge. For a greater understanding and to learn more details, an unsteady numerical model has been proposed based on a steady model. The unsteady numerical simulation was conducted under different blowing ratios (0.5, 2.0) to show their effects on film cooling effectiveness. The computational results show that the turbulence intensity downstream of a trailing edge outlet tends to be enhanced by the unsteady flow effect. Film cooling effectiveness of an unsteady model is weaker than that obtained by a steady model. When the blowing ratio is 0.5, the mixing and intersecting of the main flow and secondary flow is rapid and fierce; with the increase of blowing ratio up to 2.0, the secondary flow plays a dominant role on the flow characteristics near the outlet of the trailing edge. The mixing and intersecting of the main flow and secondary flow become smooth. The unsteady computational results agree better with the experiment results than those of steady computation. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20236     

Film cooling performance of a row of dual-fanned holes at various injection angles

Film cooling performance about a row of dual-fanned holes with injection angles of 30°, 60 ° and 90° were experimentally investigated at blowing ratios of 1.0 and 2.0. Dual-fanned hole is a novel shaped hole which has both inlet expansion and outlet expansion. A transient thermochromic liquid crystal technique was used to reveal the local values of film cooling effectiveness and heat transfer coefficient. The results show that injection angles have strong influence on the two dimensional distributions of film cooling effectiveness and heat transfer coefficient. For the small injection angle of 30 degree and small blowing ratio of 1.0, there is only a narrow spanwise region covered with film. The increase of injection angle and blowing ratio both leads to the enhanced spanwise film diffusion, but reduced local cooling ability far away from the hole. Injection angles have comprehensive influence on the averaged film cooling effectiveness for various x/d locations. As injection angles are 30 and 60 degree, two bands of high heat transfer coefficients are found in mixing region of the gas and coolant. As injection angle increases to 90 degree, the mixing leads to the enhanced heat transfer region near the film hole. The averaged heat transfer coefficient increases with the increase of injection angle.     

吹风比和唇板厚度对叶片尾缘气膜冷却的影响研究

为了探究吹风比、唇板厚度对叶片尾缘半劈缝冷却结构气膜冷却特性的影响,采用数值模拟方法对比唇板厚度为4,5和3 mm,吹风比Br为0.5,0.8,1.0和1.5条件下叶片尾缘后台阶上的气膜冷却效率。结果表明：在吹风比Br为0.5时,叶片尾缘后台阶上产生的回流区大,冷气向展向扩散范围广,冷气在近劈缝一端向展向覆盖的较好,由于吹风比小,冷气流速慢,动量小,在后台阶远端燃气与冷气掺混量大,导致冷气冷却能力降低;在大吹风比下（Br=1.5）,冷气流速快,冷气从劈缝射出集中覆盖在劈缝下游处,而肋下游冷气覆盖效果差。唇板厚度影响着唇板出口处形成的回流区,增大唇板厚度将导致半劈缝出口气流分离所产生的涡强度变大,促进燃气与冷气的掺混,降低冷却效率,薄唇板会使尾缘气膜冷却效率显著提高。     

利用红外热像技术对平板冷却的实验研究

为研究平板的气膜冷却特性,应用红外测温技术,在高温风洞试验台上对圆柱形单孔平板模型进行实验研究.采用数字图像运算技术,直接获得冷却前后平板模型的二维温度差分布.分析了在200℃时不同吹风比对平板气膜冷却效率的影响.实验结果表明:0.47＜M＜0.94时,M增大,冷却效率提高;0.94＜M＜2.24时,由于主射流掺混严重...     

Endwall heat transfer and film cooling measurements in a turbine cascade with injection upstream of leading edge

Detailed heat transfer measurements were conducted on the endwall surface of a large‐scale low‐speed turbine cascade with single and double row injection on the endwall upstream of leading edge. Local film cooling effectiveness and the heat transfer coefficient with coolant injection were determined at blowing ratios 1.0, 2.0, and 3.0. In conjunction with the previously measured flow field data, the behaviors of endwall film cooling and heat transfer were studied. The results show that endwall film cooling is influenced to a great extent by the secondary flow and the coverage of coolant on the endwall is mainly determined by the blowing ratio. An uncovered triangle‐shaped area with low effectiveness close to pressure side could be observed at a low blowing ratio injection. The averaged effectiveness increases significantly when injecting at medium and high blowing ratios, and uniform coverage of coolant on the endwall could be achieved. The averaged effectiveness could be doubled in the case of double row injection. It was also observed that coolant injection made the overall averaged heat transfer coefficient increase remarkably with blowing ratio. It was proven that film cooling could reduce endwall heat flux markedly. The results illustrate the need to take such facts into account in the design process as the three‐dimensional flow patterns in the vicinity of the endwall, the interactions between the secondary flow and coolant, and the augmentation of heat transfer rate in the case of endwall injection. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 141–152, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20007     

斜缝气膜冷却曲面模型的数值模拟

为研究燃气轮机叶片表面曲率对气膜冷却性能的影响,对二维斜缝曲面模型（凹面、凸面和平板）进行了数值模拟,选取冷却流体射流入射角35°、主射流密度比1.5,采用RNGk-ε湍流模型计算得到不同吹风比（0.5、1.2和2.0）下斜缝气膜冷却曲面模型壁面的传热系数.结果表明：低吹风比（M=0.5）时,壁面压力梯度越大,传热系数越小;中吹风比（M=1.2）时,射流对主流扰动加剧,传热加强,凹面总体传热系数比凸面小;高吹风比（M=2.0）时,曲率对传热系数的影响减弱,传热系数差异不大.     

不同吹风比下双出口孔射流气膜冷却数值模拟计算

为了获得吹风比对新型气膜冷却孔冷却效率的影响规律,利用Fluent软件求解Navier-Stokes方程,对吹风比分别为0.5、1.0、1.5和2.0时单入口-双出口孔射流冷却效率进行了数值模拟计算,得到了不同吹风比下的流场和冷却效率.结果表明：吹风比对冷却效率有很大影响;随着吹风比的提高,不同次孔方位角下的冷却效率变化规律也不相同;当次孔方位角γ=30°时,吹风比为1.0时的冷却效率最高;当γ=45°时,冷却效率随着吹风比提高而提高;当γ=60°时,冷却效率随着吹风比提高而降低;在研究高吹风比对气膜冷却效率的影响时,γ=45°最佳.     

Blowing models for cooling surfaces

To study the cooling of surfaces exposed to high temperature stress and heat flux, the blowing, or transpiration, technique is numerically investigated in the case of a porous circular cylinder. Two models are developed to simulate the blowing impact on the outer flow and an experimental set-up available allows for direct comparison and validation of the numerical simulations. The heat exchange occuring within the porous wall itself between the coolant and the solid part of the wall is accounted. The results show an excellent effectiveness of the blowing in terms of surface temperature reduction, even for low blowing ratii. The incident heat flux exhibits a maximum for medium blowing rates due to a decreasing heat transfer coefficient and a growing temperature difference between the surface and the main flow with the injection rate. Finally, the blowing is demonstrated to be very effective in cooling heavily thermally stressed parts in terms of homogeneity and coolant rate required.     

Two-Way Coupling Vortex Method and Its Application

Because of the success of the discrete vortex method for the simulation of large-scale vortex structure, many researchers extend this method to two-phase flow simulations, especially, to the simulation of particle dispersion in mixing layer, which is characterized by large-scale vortex structure. But the previous work is limited to one-way coupling, which neglects the effect of particles on fluid flow. In this paper, a discrete vortex method involving two-way coupling for two-phase flows is first proposed and then used in numerical simulation of two-dimensional gas-particle mixing layers. The numerical results show that the introduction of particles into the mixing layer has significant effects on the creation, development and merging process of large-scale vortex structures. It makes the mean size of large-scale vortex structure larger and the distance needed for development of large-scale vortex structure shorter.     

150t提钒转炉底吹元件布置物理模拟研究

通过水力学模拟实验,在1∶6的物理模型上,对承钢150t提钒转炉的底吹元件布置进行优化,运用测电导率法测定了7种不同底吹元件布置方案转炉熔池的混匀时间.实验结果表明:方案3熔池混匀时间最短,为最佳底吹元件布置方案；在本试验条件下,枪位在225 mm,顶吹气体流量为81～83.3 m3/h.,底吹气体流量为1.8 m3/...     

Effect of fuel jet arrangement on the mixing rate inside trapezoidal cavity flame holder at supersonic flow

Fuel mixing inside the supersonic combustion chamber is a significant process for development of modern scramjets. In this article, computational fluid dynamic (CFD) approach is applied to investigate the effect of various fuel injections on the mixing rate inside the supersonic combustion chamber. The mixing of hydrogen jets with four different arrangements inside the cavity flame holder is comprehensively studied. In order to examine the effect of multi jets within a cavity flameholder, a three-dimensional model is established and Navier-stocks equations are solved to simulate the flow and mixing zone inside a cavity region. Obtained results show that the injection of hydrogen jet from the bottom of cavity flame holder considerable enhances the ignition zone within the cavity. Moreover, the backward fuel injection is more superior to forward fuel injection since low-pressure vortex could significantly distribute the fuel and enlarge the mixing zone inside the cavity flame holder.     

Three-dimensional numerical study of flow and species transport in an elevated jet in crossflow

The jet fluid coming out of the elevated source behaves as the efflux of exhaust gases from a stack and the crossflow stream representing the natural wind flow. Direct numerical simulations (DNS) in an elevated jet in crossflow have been performed at a Reynolds number of 250 and a Schmidt number of 7.25. The flow field and concentration distribution of pollutants have been explored by solving three-dimensional unsteady Navier–Stokes and species transport equations using second order spatial and temporal discretization. Three different blowing ratios (0.5, 1.0 and 1.5) have been used to quantify the effect of blowing ratio on the flow field and pollutant dispersion. The blowing ratio is found have significant effect on both the flow and dispersion of pollutant. The evolution of various flow structures associated with the elevated jet in crossflow such as wakes, loop vortices is discussed. The instantaneous behavior of jet has been observed to be dependent on the unsteadiness of flow structures that varies with the blowing ratio. The downwash of jet has been observed at the lowest blowing ratio.     

Film cooling performance and heat transfer over an inclined film-cooled surface at different convergent angles with respect to highly turbulent mainstream

Experiments have been performed to study and obtain the adiabatic-wall film cooling effectiveness and the heat transfer over a film-cooled surface that is made inclined at various angles with respect to a highly turbulent flow. The film-cooled air is injected from a tangential slot. The normal temperature distributions were measured to infer the flow structure and the rate of mixing of film jet with the freestream. The freestream turbulence intensity is controlled to range from 1.0% to 26.4%, the inclination or the convergent angle of the film-cooled surface ranges from 0° to 20°, the blowing parameter from 0.5 to 2.0. It is found that the mixing of the film jet with the freestream is significantly enhanced by both the freestream turbulence intensity and the convergent angle of the film-cooled surface, which leads to the decrease in the film cooling effectiveness and the increase in the heat transfer when the inclination angle of the film-cooled surface is not large. This is attributed to the two competition mechanisms of impinging effect and the stabilization due to acceleration of the mainstream. The normal temperature distribution at several locations along the flow direction is also measured and used to infer the flow structure of the mixing of film jet with the mainstream. More detailed discussion is presented. Correlations for both the film cooling effectiveness and the heat transfer under the film-cooled surface have been very successful and are provided.     

后台阶三维缝隙冷却效率的数值模拟

针对涡轮叶片尾缘冷却结构特点,建立了后台阶三维缝隙结构气膜冷却特性计算模型,计算了冷却效率在出口壁面的分布,研究了不同雷诺数(5 000~15 000)与吹风比(0.5~2.0)影响,计算结果表明:在缝后壁面冷却效率是单调递减的,而肋后冷却效率是先增大后减少的分布规律;二次流出口壁面冷却效率受吹风比影响较大,冷却效率随吹风比增大而减小;壁面缝后冷却效率受雷诺数的影响较小。     

Improving film cooling performance by using one -inlet and double-outlet hole

The film cooling performance of a trunk-branch hole is investigated by numerical simulation in this paper. The geometry of the hole is a novel cooling concept, which controls the vortices-pair existing at the mink hole outlet using the injection of the branch hole. The trunk-branch holes require easily machinable round hole as compared to the shaped holes. The flow cases were considered at the blowing ratios of 0.5, 0.75, 1.0, 1.5 and 2.0. At the low blowing ratio of 0.5, the vortices-pair at the outlet of the trunk hole is reduced and the laterally coverage of the film is improved. At the high blowing ratio of 2.0, the vortices-pair is killed by the vortex which is produced by the injection of the branch hole. The flow rate of the two outlets becomes more significantly different when the blowing ratio increases from 0.75 to 2.0. The discharge coefficients increase 0.15 and the laterally averaged film effectiveness improve 0.2 as compared to the cylindrical holes. The optimal blowing ratios occur at M=1.0 or M= 1.5 according to the various locations downstream of the holes.     

Role of gaseous film cooling injector orientation in duct flow: Experimental Study

Experimental investigations are carried out to analyze the effect of coolant injector configuration on overall film cooling performance in a cylindrical test section similar to a rocket combustion chamber. Three different injector orientations are investigated: (i) holes parallel to core gas flow, (ii) holes at a tangential angle to the core gas flow, and (iii) compound angle holes inclined to the wall both in the tangential and azimuthal direction. The objective is to provide a consistent set of measurements for cooling effectiveness within the same test facility with respect to different blowing ratios ranging from 1.69 to 3.9. The results suggest that coolant injection parallel to the axis should be used in situations where far field effectiveness is of concern. The tangential injection, in general, shows lower wall protection compared to other schemes. The results show that the compound angle configuration augments film cooling effectiveness in the near injection regimes. However comparison of the effectiveness values for the compound injectors suggests the existence of an optimum compound angle configuration. The circumferential wall temperature data represent systematic changes in the coolant flow behavior with the change from straight injection to compound angle injection.     

动叶端壁离散孔气膜冷却的数值研究

基于某F级燃气轮机第一级动叶栅的数值模拟,以实现动叶端壁气膜冷却全覆盖为目标,分析定常下动叶端壁的流动与传热特征,拟综合考虑端壁二次流结构特征与级间封严冷气泄漏流的影响,将端壁划分为四个具有不同流动传热特征的区域,并据此设计了叶根端壁仅13孔数的离散气膜孔布置方案各区域采取不同的冷却方式根据不同吹风比下的研究结果发现:吹风比为0.75时端壁冷却有效度均值在0.2以上,实现了全端壁冷却的目标;前缘附近端壁冷却效果受吹风比影响显著,吹风比在0.75以上时冷却有效度达到0.5以上;除近压力面区域,气膜冷却效果随吹风比的增大而提高。     

150t提钒转炉模型中炉壁冲刷现象的研究

通过6:1水力学模型,对150t提钒转炉中的炉壁冲刷现象进行研究.试验中,使用电导率仪连接压力探头直接测试在纯顶吹、顶底复吹和顶底复吹增加侧枪三种状况下的炉壁上的压力变化.试验结果表明,氧枪喷孔之间的炉壁受到的压力更大,相对的区域受到的压力相对较小;底枪集中布置能降低顶吹气流对相应区域炉壁的冲刷,但底吹气流量不宜过大;...