大孔径高气速单孔气泡形成

The formation of bubbles generated in a bubble column with 190 mm I.D.from large orifices at high gas velocity was studied for air-deionized water system.The experiments were made with orifice diameters varying from 4 mm to 21 mm and hole gas velocity in the range of 0.8—154.8 m·s-1.The bubble shape and bubble size were recorded by CCD camera,critical hole gas velocity for bubble deformation was derived from the transition of aspect ratio of bubbles.The results showed that bubbles were spherical when hole gas velocity was lower than 20 m·s-1.When hole gas velocity was higher than 50 m·s-1,the shape of bubbles changed to elliptical.A correlation equation was established for bubble size as a function of hole gas velocity and orifice diameter,and the equation predicted the bubble size well for orifice diameter larger than 3 mm and hole gas velocity from 10 m·s-1 to 80 m·s-1 in air-deionized water system.

高气速下鼓泡塔中气含率分布的测定

在内径476mm的鼓泡塔内用压差法测定全塔平均气含率与表观气速的关系，进一步利用响应特性良好的双电导探针，考察了不同气速下局部气含率的分布规律。实验结果表明，利用探针法计算得到的全塔平均气含率值与压差法测定值平均误差仅为4．5％，表明探针法测量局部气含率的可靠性良好。实验还表明在高气速下，除分布板影响区外，局部气含率均类似抛物线型分布；随着气速增加，气含率分布趋于陡峭。以实验为依据，拟合了不同气速下（0．05～1．0m／s）鼓泡塔中局部气含率的关联式，认为塔内局部气含率与径向位置、表观气速和塔径等因素有关。

高气速选择性分离氨碳混和气模拟实验

采用二级串联鼓泡吸收器对NH3 /CO2 摩尔比为 2∶1的混和气体进行高气速选择性吸收 ,获得氨的总吸收率为 96 .7% ,二氧化碳的总吸收率为 33.1% ,二级吸收器出口气相CO2 摩尔含量达 90 .9% ,液相氨碳摩尔比为 5 .85。将此吸收液在加压下精馏分离氨 ,基本可以把吸收液中游离氨回收。分离游离氨后的溶液在常压下进行解吸 ,蒸馏塔出口液体含NH3 和CO2 量仅为 0 .0 14 %和 0 .0 0 6 % ,解吸气回串联吸收器进行循环吸收分离。对预计工业分离过程进行物料和能量衡算 ,分离 1kg液氨需 1MPa的蒸汽约 3.2kg。

高气速间歇式生物过滤去除高负荷H_2S

采用生物过滤法,以鸡粪堆肥和PE混合物为填料,在高气速条件下间歇式处理高负荷H2S废气。空床停留时间为20、15、10、6.7和5 s时,入口浓度3 000 mg/m3下的平均去除率分别为100%、100%、96.5%、89.2%和90.5%。高气速EBRT为5 s时,高入口负荷2 147 g/(m3.h)时的去除负荷为2 023 g/(m3.h),去除率达94%。采用Michaelis-Ment-en模型进行生物降解宏观动力学研究,其中Ks为550 mg/m3,Vm为6.8×104g/(m3.d)。结果表明,在实验温度17～24℃,湿度30%～50%下,生物过滤法间歇式处理高气速高负荷H2S的去除性能好。

L80钢在高气速湿气环境中冲蚀--腐蚀行为的环路实验

利用高温高压湿气环路研究了L80钢在高气相流速湿气环境中的腐蚀-冲蚀行为.利用腐蚀失重法测试了L80挂片在气速30 m·s-1,含水率0.0007%,CO2分压0.5 MPa及55℃的工况下,分别在不同的腐蚀周期下的腐蚀速率.利用激光共聚焦显微镜对试样表面形貌进行了观察,利用扫描电子显微镜对腐蚀产物形貌进行观察,利用X射线衍射及能谱仪对腐蚀产物组成进行了分析.结果表明,L80钢在高气相流速湿气环境下腐蚀失重严重,腐蚀后试样表面出现大量的微小蚀坑,随着实验周期的延长蚀坑会不断长大.该工况下产生的腐蚀产物主要成分为Fe3C和Fe CO3.

基于小波变换的鼓泡塔内气液两相湍流多尺度结构分析

在476mm的鼓泡塔内,以0.1～1m·s-1的高气速,利用Pavlov管测量塔内不同位置液相轴向速度,通过能谱分析发现,在空间区域上采用该方法测得的速度时间序列可分为含能尺度区和惯性子区,再借助7尺度Daubechie2小波分析的方法实现湍流量化指标如局部间歇性测度、间歇指数、尺度能量、涡旋尺寸等的评估.实验结果表明,高频和低频尺度下LIM峰分布表明湍流相干结构和大涡旋与小涡旋串级结构的存在.各小波尺度能量的比较说明,气速增大,高频和低频尺度的能量均增大,其中,含能尺度区间的能量占总能量的97%以上.不同尺度涡旋尺寸的计算证实了接近于塔内径最大涡旋的存在.进一步分析表明,塔壁处的涡旋尺寸约为塔中心处的2倍,含能尺度区间的涡旋尺寸为0.03～0.35m,气速对涡旋尺寸的影响可以忽略.湍流量化指标的分析有助于揭示湍流中的隐含结构以及高气速下鼓泡塔内湍流流动规律.

NH_3和CO_2的选择性分离II.连续吸收器研究和机理论证

用连续吸收器对 NH3 /CO2 摩尔比为 2的混合气体进行高气速选择性吸收研究 ,获得了良好的分离效果 ,选择性分离因子 S1为 3.2 5～ 8.2 3,S2 为 3.99～ 9.5 6;考察了孔口气速、孔径、液相氨浓度和插入深度等因素对选择性吸收的影响 ,结果表明 ,高气速、大孔径、浅插入和低氨浓度有利于氨的选择性吸收。数据整理证实了氨吸收的机理为气膜控制及 CO2

Test of the Relative Permeability Curve of a Gas and Oil Condensate System and its Effect on the Recovery of Oil and Gas

The relative permeability curve has been measured with simulation oil (refined oil) and gas (nitrogen or air) at room temperature and a lowpressure, both of which are very important parameters for depicting the flow of fluid through porous media in a hydrocarbon reservoir. This basic measurement is often applied in exploitation evaluation, but the underground conditions with high temperature and pressure, and the phase equilibrium of oil and gas, are not taken into consideration when the relative permeability curve is tested. There is an important theoretical and practical sense in testing the diphase relative permeability curve of the equilibrium of oil and gas under the conditions of high temperature and pressure. The test method for the relative permeability curve is proposed in this paper. The relative permeability of the equilibrium of oil and gas and the standard one are tested in two fluids, and the differences between these two methods are stated. The research results can be applied to the simulation and prediction of CVD in long cores and then the phenomenon can better explain that the recovery of condensate gas rich in condensate oil is higher than that of CVD test in PVT. Meanwhile, the research shows that the relative permeability curve of equilibrium oil and gas is sensitive to the rate of exploitation, and the viewpoint proves that an improved gas recovery rate can properly increase the recovery of condensate oil.

静电除雾技术在燃煤电厂的应用

静电除雾器具有捕集烟气中雾滴和微小尘粒的强大功能,在石化、冶金等行业已有30多年的使用历史。介绍了静电除雾器的工作原理,论述了静电除雾器在我国的发展状况,针对电厂的使用环境提出了开发高气速高效静电除雾器的技术关键点,最后指出,静电除雾技术在燃煤电厂中推广应用可为节能减排做出贡献。

ANALYSIS OF INTERNAL WAVERIDER INLET AND TYPICAL SIDEWALL COMPRESSION INLET PERFORMANCE

A new internal waverider inlet with a rectangular shape of entrance and exit in front view is designed at Ma=6.0.The design is based on a better basic flowfield ICFC than traditional one and derived with the technology of stream tracing and shock cutting.Comparison between the newly designed inlet and a typical sidewall compression inlet is given.The design Mach number and entrance shape of this new inlet are chosen according to the sidewall compression inlet.Numerical results show that most of the performance parameters of the internal waverider inlet are a bit higher than the sidewall inlet,such as the flow capture coefficient,total pressure recovery and the kinetic efficiency.The performances of these two inlets at off-design points are compared.The internal waverider inlet can capture more than 91% of incoming flow under all simulated conditions.Results show that internal waverider inlet using 3-D compression and high flow capture coefficient is a kind of fixed-geometry inlet with better performance.

Effect of simplifying bogie regions on aerodynamic performance of high-speed train

An investigation of the effect of simplifying bogie regions on the aerodynamic performance of a high-speed train was carried out by studying four train models,to explore possible ways to optimise the train underbody structure,improve the underbody aerodynamic performance,and reduce the aerodynamic drag.The shear stress transport(SST)k-ωturbulence model was used to study the airflow features of the high-speed train with different bogie regions at Re=2.25×10^(6).The calculated aerodynamic drag and surface pressure were compared with the experimental benchmark of wind tunnel tests.The results show that the SST k-ωmodel presents high accuracy in predicting the flow fields around the train,and the numerical results closely agree with the experimental data.Compared with the train with simplified bogies,the aerodynamic drag of the train with a smooth surface and the train with enclosed bogie cavities/inter-carriage gaps decreases by 38.2%and 30.3%,respectively,while it increases by 10.8%for the train with cavities but no bogies.Thus,enclosing bogie cavities shows a good capability of aerodynamic drag reduction for a new generation of highspeed trains.

Micro-bubble Drag Reduction on a High Speed Vessel Model

Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-repellent wall）, air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat （FPB） 57 m type model with the following main dimensions： L=2 450 ram, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.

Longitudinal type-line optimization of high-speed train for low aerodynamic noise

The basic head shape of high-speed train is determined by its longitudinal type-line(LTL),so it is crucial to optimize its aerodynamic performance.Based on the parametric modeling of LTL constructed by non-uniform relational B-spline(NURBS)and the fluctuation pressure obtained by large eddy simulation(LES),the Kriging surrogate model(KSM)of LTL was constructed for low aerodynamic noise,and the accuracy of the KSM was improved gradually by adding the sample point with maximum expected improvement(EI)and the optimal point from optimization.The optimal objective was searched with genetic algorithm(GA).The results show that the total fluctuation pressure level(FPL)of the optimal LTL can be 8.7 dB less than that of original one,and the shape optimization method is feasible for low aerodynamic noise design.

Development of an ε-type actuator for enhancing high-speed electro-pneumatic ejector valve performance

A novel ε-type solenoid actuator is proposed to improve the dynamic response of electro-pneumatic ejector valves by reducing moving mass weight. A finite element analysis (FEA) model has been developed to describe the static and dynamic operations of the valves. Compared with a conventional E-type actuator, the proposed ε-type actuator reduced the moving mass weight by almost 65% without significant loss of solenoid force, and reduced the response time (RT) typically by 20%. Prototype valves were designed and fabricated based on the proposed ε-type actuator model. An experimental setup was also established to investigate the dynamic characteristics of valves. The experimental results of the dynamics of valves agreed well with simulations, indicating the validity of the FEA model.

Investigation on aerodynamic noise reduction for snow-plough of high-speed train

A set of acoustic optimization design methods is established by combining the flow field deterioration theory and the acoustic analogy theory,and applied to the acoustic optimization design of high-speed train snow-plough.The results show that the streamline bodies of the head/tail car are the most important sound sources,respectively,accounting for 23.7%and 33.7%of the total sound energy.Compared with the streamline body of tail head,the streamline body of head car is more biased towards high frequency for the sound source energy.The A-weighted radiated noise of the train body is characterized by broadband sound(mainly in the range of 1-4 kHz)and peak features(especially at 2 kHz).The snow-plough with the maximum expansion length can mitigate the strong peak effect of the sound at 2 kHz,reduce the total sound energy,and show the best acoustic radiation performance in the four schemes.The numerical computation model was checked by the wind tunnel test results.

Comparative investigations of pressure waves induced by trains passing through a tunnel with different speed modes

Pressure waves induced by high-speed trains passing through a tunnel have adverse effects on train structures and passenger comfort. These adverse effects can be alleviated when the train passing through the tunnel with a speed mode of deceleration. Thus, to investigate the effect of speed modes on pressure waves, three-dimensional compressible unsteady Reynolds-averaged Navier-Stokes simulations and the sliding mesh are used to simulate pressure waves on train surfaces and tunnel walls when trains passing through a tunnel with three different speed modes(a constant speed at350 km/h, a uniform deceleration from 350 to 300 km/h, and another uniform deceleration from 350 to 250 km/h).Compared with the constant speed, the peak-to-peak of the train surface pressure under the other two speed modes reaches a maximum difference of 11.0%. The maximum positive pressure difference of the tunnel wall under different speed modes is caused by the different attenuation of the friction effect when the train enters the tunnel, and the maximum difference is 12.8%. The difference of the maximum negative pressure on the tunnel wall is caused by the different speed and pressure wave intensity of the train arriving at the same measuring point in different speed modes,and the maximum difference is 15.8%. Hence, it can be concluded that a speed mode of deceleration for trains passing a tunnel can effectively alleviate the aerodynamic effect in the tunnel, especially for the pressure on the tunnel wall.

Aerodynamic noise characteristics of high-speed train foremost bogie section

This paper investigates the main scale analysis of the aerodynamic noise in the foremost bogie area by the large-eddy simulation(LES)and the Ffowcs Williams-Hawkings(FW-H)analogy.The mechanism of the aerodynamic noise in this area has been excavated.The aerodynamic excitation results show that the bogie divides the bogie compartment into two cavities,each of which contains a large circulating flow and presents multi-peak characteristics in the frequency domain.The far-field noise results suggest that in the speed range of 200−350 km/h,the aerodynamic noise mechanism in the bogie area is the same.Cavity noise is the main noise mechanism in the foremost bogie area,and the bogie divides the bogie cabin into two cavities,thereby changing the aerodynamic noise in this area.

Wind tunnel tests on aerodynamic characteristics of vehicles on same-storey highway and rail bridge under crosswind

In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.

Experimental study on aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds

In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.

Numerical Investigation of an Active Jet Control Method for Hypersonic Inlet Restart

A flow control method based on an active jet is developed to restart hypersonic inlets. The dynamic restarting process is numerically reproduced by unsteady Reynolds averaged Navier-Stokes(RANS) modeling to verify the effectiveness and reveal the influence of jet conditions. The active jet improves the inlet unstart status by drawing the high-pressure separation bubble from the internal compression duct and performing a full expansion to alleviate the adverse pressure gradient. Moreover, the favorable pressure gradient in the inlet caused by jet expansion allows for a successful restart after turning off the jet. The influence of the jet momentum ratio is then analyzed to guide the design of the active jet control method and choose the proper momentum ratios. A low jet momentum does not eliminate the high-pressure separation bubble, whereas an excessive jet momentum causes severe momentum loss due to the induced shock. The general rule in restarting the inlet using an active jet is to allow a full jet expansion downstream of the jet slot while avoiding excessive momentum loss upstream and preventing the thick low-speed layer.