共查询到20条相似文献,搜索用时 187 毫秒
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基于声学矢量层析成像原理,对炉内二维速度场进行重建,实现炉内速度场的在线监测。针对炉内典型测量二维截面,布置8个有效声学测点,选取四角切圆简化模型速度场进行重建仿真。使用6个参量标定模型速度场,通过拟牛顿迭代法确定模拟速度场参数。对重建结果加入6%以内的随机扰动后重建结果仍然可靠,验证了该算方法的准确性和稳定性,可为大型电站锅炉速度场声学测量提供指导。 相似文献
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《热能动力工程》2016,31(3)
为了获得较为精确的炉膛燃烧二维温度场,达到实时监测炉膛内火焰温度的目的,分别利用光学法与声学法建立温度场重建模型并推导出较为简便的矩阵反演公式,并结合SVD(奇异值分解)算法对炉膛内二维温度场进行重建。数值研究表明:在测量误差均为0.05和0.1时,光学与声学测量方法分别在高温区域与低温区域有较好的重建效果,据此提出了基于层次分析法的声、光联合温度场重建技术,当采用(声、光)联合技术对炉膛单峰对称、单峰偏置和双峰对称温度场进行二维重建时,反演精度较光学法或声学法均提高0.01左右,表明了此种融合方法的可行性和准确性,对炉膛温度场反演具有重要意义。 相似文献
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研究了利用激光数码全息技术实现两相流三维空间速度场测量的方法.用1台脉冲激光器照射两相流,平面光和颗粒衍射光发生干涉,在数码相机的CCD平面上生成全息图像.用1台跨帧数码像机连续拍摄两相流全息图像,对全息图应用基于小波变换的三维图像重建算法,在计算机上实现物体三维图像的重建,再利用图像互相关测速技术从连续的重建三维图像中提取两相流三维空间的速度场.实验中将2只置于不同空间位置的喷嘴向不同方向喷射雾化的气液两相流,并对生成的流场进行测量.结果表明该方法可以实现两相流三维空间速度场测量. 相似文献
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干熄炉内焦炭下降的粘性流模型及其比较研究 总被引:1,自引:0,他引:1
干熄焦工艺中干熄炉内焦炭下降运动对熄焦质量起着至关重要的作用。根据流体力学理论,采用介质连续性假设,在Euler场中建立粘性流模型,得到干熄炉内焦炭下降运动的数学模型,并采用基于交错网格的SIMPLE算法来求解对流扩散方程。通过数值求解,得到了焦炭下降的速度场,计算结果和实验数据吻合较好,并且固体颗粒粘性系数显著影响干熄炉内下部焦炭运动。通过将粘性流模型与势流模型、动力模型的计算结果进行比较,表明粘性流模型能全面地描述干熄炉内焦炭下降运动。 相似文献
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An experimental technique is presented to non-intrusively measure the quasi-instantaneous aerodynamic loads and surrounding pressure field for a turbine by using particle image velocimetry (PIV). The PIV measurements provide the velocity flow field needed to calculate the pressure field around the turbine using three different methods. In the first method, the quasi-instantaneous and mean pressure fields are obtained by solving the Poisson equation and by calculating the boundary conditions from the Navier–Stokes equations. In the second method, the pressure at the boundaries is determined by spatial integration of the pressure gradient. In the third method, the pressure is calculated using the Bernoulli equation. The experimental results are compared to aerodynamic load theoretical predictions from the Blade Element Momentum theory (BEM). An analysis of the experimental results showed the importance of the local acceleration, convective and pressure terms when calculating the forces and the pressure field in a stationary reference frame. Only the Poisson method includes all these terms, and had a small standard deviation between the calculated instantaneous forces. Furthermore, the Poisson method results are independent of the control volume size investigated while the other two experimental methods are affected. This experimental technique could be used to simultaneously replace instrumentation such as force balance and pressure taps while providing for the first time quasi-instantaneous information about the surrounding flow in any turbine immersed in an incompressible flow. In addition, it could be applied to evaluate unsteady wind loads and aerodynamic stall and also provide much needed information for validating computational studies. 相似文献
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A New Calculation Method of the Axial and Radial Velocity and Grade──Efficiency for High──Efficiency CyclonesANewCalculationM... 相似文献
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At present in China, the cyclones are widely used in the dust removal ventilation system of boilers, industry furnaces or
pits etc., because of their simple structure, long life and cost efficiency. In order to improve efficiency of the cyclones,
new theoretical calculation method is very important. In this paper, the concept of down-flow quantity is introduced and new
formula is deducted based on Kilven law and the work has done by Zhao Weizhong[1]. The formula is not only of advantage theoretically but also fit with experimental results quite well. On the basis, the
effect of three-dimensional velocity distribution in the flow field within cyclones and other parameters on the grade-efficiency
calculation are analyzed and a new equation for grade-efficiency estimation is introduced. The calculating accuracy of the
equation is better than the others theoretically and experimentally. 相似文献
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现代水力机械叶片设计时采用的翼型大多为空气动力学翼型,而较少关注水流场与空气流场的差异及流质改变对翼型流动特性的影响,因此选取七种翼型,基于CFD软件,在高雷诺数、小攻角下,对翼型在水、空气两种流场中绕流的升阻力、表面涡量分布、速度场进行二维数值模拟计算,并分析了两种流场中的差异,提出了水、空气两种流场中升力、阻力系数的差异修正系数,推导了以水(气)流场试验数据表达的相同条件下气(水)流场运动方程。结果表明,气流场、水流场的差异对翼型升力系数的影响较小,对阻力系数及升阻比的影响较大;水流场中,翼型表面涡量不存在较大波动,分布更为均匀稳定,且分离点位置集中于翼型中段;水、空气流场的尾流低速区域面积之比能够较好地反映阻力系数的差异修正系数。研究成果可用于指导不同流场中的翼型设计。 相似文献
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The supersonic multi-hole probe is an essential test tool for wind tunnel experiments, which is necessary to develop the basic research of improving the measurement accuracy and expanding the application of the probes. 相似文献
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变负荷工况下锅炉对流受热面污染的监测 总被引:2,自引:1,他引:2
针对在线监测大型电站锅炉受热面污染的需要,讨论了稳定负荷的计算模型无法用于变负荷工况监测的原因,分析了变负荷过程中各物理参数的变化机理,从热量平衡出发,考虑了金属管壁蓄热及蒸汽蓄热对受热面污染计算的影响,推导了变负荷工况下的污染监测模型及实时计算方法.以某电厂300MW机组锅炉的低温对流过热器为计算对象,采用现场实时数据进行了变负荷工况下受热面污染监测计算.提出了考虑金属及工质蓄热的锅炉变负荷污染监测模型与计算方法,基本能够消除负荷变化对受热面实际污染率计算的影响,得到比较合理的污染率计算结果,对改进现有的根据热平衡算法的锅炉受热面污染在线监测模型有重要的参考价值和工程实际意义. 相似文献
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三相共箱式气体绝缘母线的热计算及散热性能研究对于其可靠性设计及在线监测具有重要意义。根据流体力学理论,采用流体多组分有限元法对三相共箱式气体绝缘母线进行热计算,利用映射网格划分实现电磁场、温度场和流体场的间隔耦合,综合考虑了母线外壳内外气体的流动和温度变化特性。采用流体单组分有限元法、流体多组分有限元法、传热学解析公式法三种方法进行计算,并对比分析了计算结果与试验结果的精度。结果表明,多组分有限元法与试验结果最为接近,为气体绝缘母线的设计及在线监测提供了理论基础。 相似文献
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Qun Chen Jianxun Ren Ji-an Meng 《International Journal of Heat and Mass Transfer》2007,50(25-26):5334-5339
A field synergy equation with a set of specified constraints for turbulent heat transfer developed based on the extremum entransy dissipation principle can be used to increase the field synergy between the time-averaged velocity and time-averaged temperature gradient fields over the entire fluid flow domain to optimize the heat transfer in turbulent flow. The solution of the field synergy equation gives the optimal flow field having the best field synergy for a given decrement of the mean kinetic energy, which maximizes the heat transfer. As an example, the field synergy analysis for turbulent heat transfer between parallel plates is presented. The analysis shows that a velocity field with small eddies near the boundary effectively enhances the heat transfer in turbulent flow especially when the eddy height which are perpendicular to the primary flow direction, are about half of the turbulent flow transition layer thickness. With the guide of this optimal velocity field, appropriate internal fins can be attached to the parallel plates to produce a velocity field close to the optimal one, so as to increase the field synergy and optimize the turbulent heat transfer. 相似文献