苏玛罐静态加湿方法研究及应用

基于加湿水量计算公式使用苏玛罐配备的标准加湿气体,气体匀速放出时实际测得出口湿度有时与预期湿度相差较大。为正确配置与预期湿度相符的标准加湿气体,通过对比最终填充压力与罐内气体湿度的关系,发现体积一定的苏玛罐在不同温度下有加水上限。苏玛罐内加入水未过量时,苏玛罐出口可测得稳定输出的相对湿度;苏玛罐内加入过量水后,实际测得相对湿度不稳定,过量的水在苏玛罐内发生冷凝,导致亲水性挥发性有机物质的损失,气体测试浓度偏低。故苏玛罐进行加湿时,需计算其最大填充压力,使最终加水量不超过其最大加水量。此外,若苏玛罐内已发生冷凝,可通过对苏玛罐、阀、管路全程加热,提高最大加水量,保证苏玛罐内水完全气化,输出稳定相对湿度且无化合物损失的气体。

正丁醇稀燃燃烧持续期的试验研究

针对过量空气系数1.6的稀混合气,本文以燃烧弹内填充压力和介质初始温度条件分别作为独立变量,对正丁醇的燃烧持续期进行试验研究。通过改变填充压力与介质温度边界条件,在定容燃烧弹上进行了燃烧试验,分析了燃烧压力、压力升高率、燃烧温度、放热量、放热率等燃烧特性参数,得出填充压力与介质温度条件对正丁醇稀燃燃烧持续期的影响规律。研究结果表明,随着填充压力的增大,正丁醇燃烧持续期明显缩短,混合气温度比初始填充压力对燃烧持续期的影响大。该研究为发动机燃用正丁醇的推广提供了理论依据。

高炉炮泥剪切应力的测定

根据高炉出铁口用炮泥的形变特点可以调整其填充压力的大小。通常在50℃～80℃温度范围内,采用马歇尔实验得到的挤出压力数值评价高炉炮泥的形变特点。然而,有些情况下炮泥的挤出压力和填充压力之间不能够充分的相互对应。作者认为,在某个温度范围内,炮泥中含有的液体焦油粘度最低,这时能够更好地评价炮泥的形变特点。基于这种假设,从而开发了能够评价高温条件下炮泥形变特点的剪切试验。比较了70℃和300℃温度条件下的剪切试验结果和填充压力之后得知,在300℃条件下进行评价比70℃条件下的评价更优越。另外,定量地分析了原料的特点和试验温度对剪切试验结果产生的影响。

固体火箭发动机燃烧室内声波振荡的数值研究

固体火箭发动机中声波振荡是引起不稳定燃烧的一个重要原因。通过对固体火箭发动机不同药型燃烧室压力填充瞬态过程进行数值模拟,得出在燃烧室压力填充瞬间,燃烧室会产生较高频率的纵向声振。加堵盖和不同的喷喉大小以及燃烧室长度变化等因素会对声振产生不同的影响。计算结果表明,这些影响包括了声振的强度、阻尼和频率,发动机点火后喷管喉部尺寸和堵盖打开的时间影响到振荡波的发展和消失。

Numerical simulation of hydraulic fracture propagation in weakly consolidated sandstone reservoirs

Frac-packing technology has been introduced to improve the development effect of weakly consolidated sandstone.It has double effects on increasing production and sand control.However,determining operation parameters of frac-packing is the key factor due to the particularity of weakly consolidated sandstone.In order to study the mechanisms of hydraulic fracture propagation and reveal the effect of fracturing parameters on fracture morphology in weakly consolidated sandstone,finite element numerical model of fluid-solid coupling is established to carry out numerical simulation to analyze influences of mechanical characteristics,formation permeability,fracturing fluid injection rate and viscosity on fracture propagation.The result shows that lower elastic modulus is favorable for inducing short and wide fractures and controls the fracture length while Poisson ratio has almost no effect.Large injection rate and high viscosity of fracturing fluid are advantageous to fracture initiation and propagation.Suitable fractures are produced when the injection rate is approximate to3–4m3/min and fluid viscosity is over100mPa?s.The leak-off of fracturing fluid to formation is rising with the increase of formation permeability,which is adverse to fracture propagation.The work provides theoretical reference to determine the construction parameters for the frac-packing design in weakly consolidated reservoirs.

Characterizing pressure fluctuation into single-loop oscillating heat pipe

The pressure characteristics inside single loop oscillating heat pipe （OHP） having 4.5 mm inner diameter copper tube with the loop height of 440 mm were addressed. Distilled water was used as working fluid inside the OHP with different filling ratios of 40%, 60% and 80% of total inside volume. Experimental results show that the thermal characteristics are significantly inter-related with pressure fluctuations as well as pressure frequency. And the pressure frequency also depends upon the evaporator temperature that is maintained in the range of 60-96 ℃. Piezoresistive absolute pressure sensor （Model-Kistler 4045A5） was used to take data. The investigation shows that the filling ratio of 60% gives the highest inside pressure magnitude at maximum number of pressure frequency at any of set evaporator temperature and the lowest heat flow resistance is achieved at 60% filling ratio.

Stability study on naturally filling body in gob-side entry retaining

In the construction of the filling gob-side entry retaining in a lane, we utilize the self-slide natural phenomenon of a falling gangue in an inclined coal seam goaf. First, we put the falling gangue of goal above the laneway and made it the main filling material by adopting the measurement of flexible supporting system combined with those of rigid supporting system. Then we made the filling material gunited and solidified to maintain the filling goal of the gob-side entry retaining beside the lane. Considering the law of energy conservation and law of pressure distribution for retaining the active and Static soil of the wall, we analyzed the reliability of a gangue blocking facilities and the stability of the filling mate- rial in the lane. We analyze the figures to see the stability. The result shows that the gangue block sup- porting system is reliable, and has been successfully practically applied.

Realizing of Optimization of Binder Backfill Material Under Certain Strength with Fuzzy Sets

The main factors deciding the compressive strength of binder backfill body are tailing density and binder dosage in binder backfill materials. Based on the antecedent of certain pulp density, the method of increasing the tailing density and reducing the binder dosage, or the manner of cutting down the tailing density and gaining the binder dosage are taken to guarantee the strength of backfill body. The problem that should be solved is how to determine the tailing density and the binder dosage rationally. This paper tries to realize the correct selection of the tailing density and the binder dosage in computer with the method of fuzzy mathematics.

Influence of infilling stiffness on mechanical and fracturing responses of hollow cylindrical sandstone under uniaxial compression tests

Hollow cylindrical sandstone specimens filled with Al,Pb and polymethyl methacrylate(PMMA),as well as hollow and solid specimens were tested under monotonic unconfined compression.The discrepancies in the elastic modulus,unconfined compressive strength and failure pattern of the specimens were studied and then illustrated.The interaction stress threshold and localized failure stress threshold were identified by the strain gauges on the rock and filling rod.The results indicated that unobvious changes in the strength and elastic modulus were found between the solid and hollow specimens,while for the hollow specimens with infillings,the strength decreases with increasing the stiffness of the infilling material.The filling material with a higher stiffness leads to a high hoop stress,and hence a stronger interfacial force.The specimens coupled with filling rod are mainly fractured with tensile cracks,while the solid and hollow specimens are typically split into blocky fragments with dominated shear fractures.Finally,the equivalent inner pressure in the opening was theoretically derived.The findings suggested in the experiments can be well explained using the theoretical thick-walled cylinder model.

Hydrodynamic Behavior in a Rotating Zigzag Bed

As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating discs,forming zigzag channels for liquid-gas flow and mass transfer.As in RPBs,some hydrodynamic behavior in RZB is interesting but no satisfactory explanation.In this study,the experiments were carried on in a RZB unit with a rotor of 600 mm in diameter using air-water system.The gas pressure drop and power consumption were measured with two types of rotating baffle for RZB rotors,one with perforations and another with shutter openings. The circumferential velocities of gas were measured with a five-hole Pitot probe.The pressure drop decreased rapidly when the liquid was introduced to the rotor,because the circumferential velocity of the liquid droplets was lower than that of the gas,reducing the circumferential velocity of gas and the centrifugal pressure drop.The power consumption decreased first when the gas entered the RZB rotor,because the gas with higher circumferential velocity facilitates the rotation of baffles.

Influence of filling atoms on radial collapse and elasticity of carbon nanotubes under hydrostatic pressure

Using molecular mechanics and molecular dynamics simulations, we focus on the influence of filling atoms on radial collapse and elasticity of single-walled carbon nanotubes(SWNTs). It is shown that the filled argon(Ar) and silicon(Si) atoms can effectively improve the resistance to high pressure and radial elasticity of SWNT, which may attribute to the strong repulsive force from the filled Ar(Si) atoms. However, due to the strong interaction of Cu atoms, filling Cu atoms deteriorate SWNT's radial elasticity. In addition, it is found that the phase transitions of the atoms filled in SWNT occur in the process of loading and unloading pressure, so that the electrical properties of the SWNTs filled with atoms change in the process of loading and unloading pressure. In view of the restorability of SWNT filled with Si atoms upon unloading, the filled SWNTs can be used to develop a new class of nano-electronic devices such as pressure sensor, relay and memory, etc.