Characteristics of Heat Transfer Control on Offset-type Turbulent Impinging Jet

偏置型湍流冲击射流传热控制特性

• 批准号: 04650178
• 负责人: ICHIMIYA Koichi
• 金额: $ 1.28万
• 依托单位: Yamanashi University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650178/
• 关键词: Thermal Engineering; Forced Convection; Impinging Jet; Heat Transfer Experiment; Inclined Nozzle; Liquid Crystal; 強制対流

Thermal energy should be saved to the next generation. Offset-type impinging jet is a representative method to improve and augment the local heat transfer or mass transfer. In practical applications, the attitude of the nozzle in comparatively narrow space with confined wall is an important factor including the compactness of the facility.In 1992, the heat transfer characteristics of an oblique turbulent impinging jet were performed experimetaly by using air as a working fluid. The nozzle diameter was 30 mm and also the distance between the nozzle and the impingement surface 30 mm. The confined wall was set at the same level of the nozzle. The inclined angle was 45ﾟ, 60ﾟ and 90ﾟ. The impingement section was composed of an transparent acrylic plate, the thermosensitive liquid crystal sheet and the stainless steel foil whose thickness was 20 mu m. Three kinds of optical filters were mounted one after another in front of the lens of the CCD camera. The color image of thermosensitive liqui … More d crystal was converted into an electric signal. The size of one pixel was 0.5-1mm square. The relationship between color and temperature was calibrated to determine the accuary and resolution. The scatterd reflected light from the liquid crystal at a given temperature was divided into three components (Red, Green, Blue) of color by optical filters. The brightness of each component was obtained at each pixel as the image data. The temperature was estimated by the regression equation including the relative brightness. The local heat flux was compensated locally by using the detailed temperature distribution and solving the three-dimensional thermal conduction equation in the heated section. According to the results, the local Nusselt number showed the peak shift and the plateau. The effect of the local heat flux is remarkable at low Reynolds number and amounts to 6-17% of uniform flux.In 1993, the flow characteristics of an oblique turbulent impinging jet were carried out by using a thermoanemometer. The velocity and turbulent intensity across the section were measured in unheated condition. The probe was set against the flow and parallel to the impingement surface. According to the results, the jet from the nozzle rolled down the sorrounding stationary fluid and impinged the flat surface. The rolling down of the flow and the amplification of turbulence near the impingement surface were performed at the minor flow region and promoted the local heat transfer. The gradient of these flow parameters (velocity and fluctuation intensity) seem to affect the local heat transfer enhancement as their absolute vaues do. The superior frequency in power spectrum of velocity fluctuation affecting heat transfer improvement was from 80 to 300 Hz and depended on Reynolds number.These results will be applied in the practical facility as the basic data. Less

热能应该节约到下一代。偏置式冲击射流是一种具有代表性的改善和强化局部换热或传质的方法。在实际应用中，在较窄的受限空间内，喷嘴的姿态是影响设备紧凑性的重要因素。1992年，以空气为工质，对倾斜湍流冲击射流的换热特性进行了实验研究。喷嘴直径为30 mm，喷嘴与撞击面的距离为30 mm。约束墙设置在与喷嘴相同的高度。倾斜角度分别为45ﾟ、60ﾟ和90ﾟ。撞击段由透明亚克力平板、热敏液晶片和厚度为20微米的不锈钢箔组成，三种滤光片相继安装在CCD相机的镜头前。热敏液体…的彩色成像更多的d晶体被转换成电信号。每个像素大小为0.5~1 mm的正方形。校正了颜色与温度的关系，确定了精确度和分辨率。通过滤光片将液晶在一定温度下的散射反射光分成红、绿、蓝三种颜色分量。在每个像素处获得每个分量的亮度作为图像数据。通过包含相对亮度的回归方程来估计温度。利用详细的温度分布和求解加热段的三维热传导方程，对局部热流进行局部补偿。结果表明，局地Nusselt数呈现峰值漂移和平台化现象。当雷诺数较小时，局部热流的影响非常显著，相当于均匀热流的6-17%。在不加热的情况下，测量了横截面上的速度和湍流强度。探头设置在对流方向，平行于撞击面。结果表明，从喷嘴喷出的射流沿着分离的静止流体滚落并撞击平坦的表面。在较小的流动区，冲击面附近的流动发生下滚和湍流放大，促进了局部换热。这些流动参数(速度和脉动强度)的梯度似乎和它们的绝对值一样影响局部换热强化。影响换热效果的速度脉动功率谱的最优频率为80~300 Hz，且与雷诺数有关，这些结果将作为基础数据应用于实际装置中。较少

项目成果

Koichi Ichimiya: "Heat Transfer Characteristics of an Oblique Impinging Jet with Confined Wall" Proc.of 3rd World Conference on Experimental Heat Transfer,Fluid Mechanics and Thermodynamics. 1. 605-610 (1993)

Koichi Ichimiya：“带有受限壁的倾斜冲击射流的传热特性”第三届世界实验传热、流体力学和热力学会议论文集。

Koichi Ichimiya: "Heat Transfer Characteristics Caused by Circular Jets with Confined Wall" Proc.of 2nd JSME-KSME Thermal Engineering Conference. 2. 447-452 (1992)

Koichi Ichimiya：“有限壁圆形射流引起的传热特性”第二届 JSME-KSME 热工会议论文集。

Koichi Ichimiya: ""Heat Transfer Characteristics of an Oblique Impinging Jet with Confined Wall"" Transactions of Japan Society of Mechaninal Engineers.vol.59. 1698-1703 (1993)

Koichi Ichimiya：“带有受限壁的倾斜冲击射流的传热特性”，日本机械工程学会会刊，第 59 卷。

一宮 浩一: "比較的狭い空間における斜め円形衝突噴流の伝熱特性" 日本機械学会論文集B編. 59. 1698-1703 (1993)

Koichi Ichinomiya：“相对狭窄空间中倾斜圆形冲击射流的传热特性”，日本机械工程师学会会刊，B 版，59. 1698-1703 (1993)。

Koichi Ichimiya: "Heat Transfer and Flow Characteristics of an Oblique Turbulent Impinging Jet with Confined Wall" Heat Transfer in Turbulent Flows HTD(ASME). 246. 17-24 (1993)

Koichi Ichimiya：“带有限壁的倾斜湍流冲击射流的传热和流动特性”湍流中的传热 HTD（ASME）。