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Based on the highresolution body wave tomographic image and relevant geophysical data, we calculated the form and the vertical and tangential velocities of mantle flow.


The velocities of the vertical mantle flow are about 14 cm per year and the tangential velocities are 110 cm per year.


The model was tested for the case of tangential stresses when studying the polyacrylamidealuminium acetate solutions and for the normal stresses, when studying the strain of the rock samples saturated with oil.


The flow of a simple gas along a plane surface under the action of tangential temperature gradient is considered.


We study a magnetic field distribution that is nonuniform and sheared like in tangential discontinuities.

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 In this paper the boiler DG 670/140 for 200 MW power units made in Dongfang Boiler Works is described. Two versions of boilers, oil fired or coal fired, are supplied. Oil fired boilers have been put into operation for five years already. The main operating performances have been found to fulfil the design requirements quite well. Tangential firing, dampers regulation of reheat steam temperature by dampers and membranewalls are adopted in the coal fired boilers. Boilers of this type are designed to burn... In this paper the boiler DG 670/140 for 200 MW power units made in Dongfang Boiler Works is described. Two versions of boilers, oil fired or coal fired, are supplied. Oil fired boilers have been put into operation for five years already. The main operating performances have been found to fulfil the design requirements quite well. Tangential firing, dampers regulation of reheat steam temperature by dampers and membranewalls are adopted in the coal fired boilers. Boilers of this type are designed to burn a wide range of coals such as biluminous coal, lean coal, lowgrade washed coal and common anthracite.  本文介绍东方锅炉厂制造的配20万千瓦发电机组的DG670/140型锅炉。其中有燃油锅炉和燃煤锅炉两种。油炉已投运五年,主要运行指标达到了设计要求。煤炉采用四角切向燃烧,烟气挡板调温,炉体全密封结构。锅炉设计充分考虑了煤种适应性,该型锅炉可适用于烟煤、贫煤、劣质洗煤和普通无烟煤。  Research results of the cold aerodynamic flow characteristics of a bluffbody flame stabilizer mounted on the outlet of a tangential burner are reported. From an analysis of the data L, mR/m0, Csp, B and Wm/W0, it is proposed that the bluffbody flame stabilizer can be used for the power plant boiler to intensify the firing of pulverized coal and air mixture.  本文主要介绍在直流式燃烧器出口加装钝体稳燃器后的冷态空气动力特性的研究成果.根据对回流区长度L、回流率m_R/m_0、静压系数C_(SP)、阻力系数ξ、扩张角β和速度衰减率测量数据的分析,认为钝体稳燃器可用于电站锅炉,以强化气粉混合物的着火.  This method, suitable for digital computation, is used for calculating all the natural frequencies, mode shapes and their resonantvibration stress for a banded group of turbine twisted buckets vibrated in tangential, axial and torsional directions.In this approach, the buckets are connected elastically with a continuous beam and, as the following factors are considered, the calculation is done more accurately.a. Twist of blade.b. Modification due to the effect of shear deformation and rotary inertia in... This method, suitable for digital computation, is used for calculating all the natural frequencies, mode shapes and their resonantvibration stress for a banded group of turbine twisted buckets vibrated in tangential, axial and torsional directions.In this approach, the buckets are connected elastically with a continuous beam and, as the following factors are considered, the calculation is done more accurately.a. Twist of blade.b. Modification due to the effect of shear deformation and rotary inertia in buckets and band.c. The effect of centrifugal force in revolution of a banded group.d. Part of the root of bucket participated in vibration.It does not only calculate tangential bending vibration in Ao, Po and Al modes, but also axial bendingtorsional vibration in X, U and S.,nodes and different torsional modes.Through the comparison of more than ten stages with short and mediumheight steam turbine buckets in large power units, we found the values of calculation basically agree with the measurement in the power plant.Having calculated the frequencies and modes of a banded group, we use the principle of energy conservationduring the steady resonant state of a banded group, within a vibration cycle, the energy supplied to the blades of the banded group by the existing force acting on tangential, axial and torsional directions is equal to the energy dissipated in damping on the above directions for all buckets in groupto calculate the real displacement and resonantvibration stress of blade, root of buckets, band and rivets in group for different known vibration modes. At the same time, according to the fatigue strength of the material, steady stress, structure, technology and the operating condition, we get the permissible fatigue stress of material for judging the safety of the vibration stress. The author found that the result of the calculation of "169" accident of stages and the safe operating stages, an improved design of the original "169", agreed with the real circumstances.This method is mainly used to calculate short and wediumheight blade group. The author analyses the accident of the firststage in French KT1501 steam turbine unit used in the whole set equipments with a capacity of 300,000 tons/year synthesized ammonia. The coefficient in calculationthe fractional stimulus S and logarithmic decrement δ derive from the French data. The calculating frequencies basically agree with the measmement and, according to the vibration stress value, we get the conclusion of the calculation for the accident stage as follows.1. The abruption accidents of the first stage in the original rotor (the 1st, 2nd and 3rd accidents) were due to axialtoisional resonanceU mode for four bucket's group and x mode for three bucket's. Although the blades and band were safe, the resonantvibration stress of bucket root were unsafe and that of the rivet was large. Also, when extra fluctuating bending moment was applied from forced band vibration by steam inlet in partial circumference, the rivet was in danger. After two rivets had been used on the blade, the rivets were safe, but fatigue still occured in bucket root (as in the 5th accident)2. The abruption accident of the firststage in the new rotor (the design was improved by the French but the abruption still took place as in the 4th accident) was due to a tangential resonance with Bo mode; its resonant stress of the bucket root was more than the permissive vibration stress of the material, thus causing it to fatigue abruption.The results of the calculation agree with the abrupting position and the surface of the crack in these accidents. Therefore, the author is of the opinion that all the five abru ption accidents that happened in the past were mainly due to the design of the banded group, not to the operation or defect of the material used.  本文叙述由汽轮机围带扭叶片组各类计算振型、按能量守恒原理进一步算得在发生各类振型的共振时叶片组叶身、叶根、围带及铆钉的振动应力。并根据材料的许用耐振强度判断其共振的安全性。本法主要用来计算电厂汽轮机中等长度的叶片。这里也计算了曾发生五次振动断裂的法国进口机组第一级动叶,计算结果表明该级原先叶片主要是由于2nZ喷咀激振力引起的叶片组轴向弯曲U型共振断裂。经法国修改设计后,仍旧断裂,但断于nZ喷咀激振力引起的叶片组切向弯曲B_o型共振。计算结论与实际事故部位及断口分析符合。   << 更多相关文摘 
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