涡流室式柴油机非对称主燃烧室的试验研究

本文提出将新鲜空气较多地集中在涡流室柴油机的主燃烧室偏进气门一侧的容积里对燃烧有利的观点,根据此观点设计研制了非对称式主燃烧室,在S195柴油机上进行了试验验证,结果表明,改善了发动机的动力指标,降低了油耗率。     

Regression Rate Studies of Paraffin Wax‐HTPB Hybrid Fuels Using Swirl Injectors

Studies on the regression rates of three compositions of paraffin wax‐HTPB hybrid fuel grains in a stream of gaseous oxygen using two different swirl injectors at a fixed injection pressure were carried out. It was found that the regression rate in the hybrid fuel increases with increasing paraffin wax percentage, which may be attributed to melt‐flow effects. The local regression rates, average regression rates, fuel mass consumption rates, and total mass fluxes for the hybrid fuels were found to be dependent on the swirl injector configuration. All three hybrid fuels were characterized by scanning electron microscopy (SEM). Furthermore, the thermal stability and thermal degradation behavior of the hybrid fuels were investigated by DTA/TGA techniques.     

Flow and mixing characteristics of swirling wakes in blockage-effect regime

The flow structures and turbulence properties of swirling bluff-body wakes are studied via the velocity fields measured by a two-component laser Doppler velocimeter. The velocity vectors, streamline patterns, vorticities, velocity distributions, and turbulence properties are presented and discussed. The streamline patterns show two characteristic flow modes, single bubble and dual rings, in the bluff-body effective regime. The single bubble is a closed recirculation bubble with a stagnation point on the central axis. Unsteady large-structure flow motions in the bubble result in high turbulence intensities. The dual-ring flow structure is an open-top recirculation zone, in which a pair of large-vorticity-containing counter-rotating vortex rings exists. The dual rings induce a central swirling jet to stabilize on the circular disc and expel the flows in the dual rings to the downstream area. In order to obtain and compare the mixing capabilities of the single-bubble and dual-ring flow structures, the tracer gas is released into different regions of the wake, then the concentration distributions are measured. Both the flow characteristics and tracer-gas concentration distributions are analyzed and logically argued to elucidate the influences of the flow patterns and turbulence properties on the mixing capability.     

Investigation of the turbulence characteristics in the swirling flow of a gun-type gas burner with two different hot-wire probes

Mean velocities and turbulence characteristics in the swirling flow of a gun-type gas burner (GTGB) were measured with a triaxial hot-wire probe (T-probe) and compared with previous data measured with an X-type hot-wire probe (Xprobe). Vectors and axial mean velocity data obtained by the measurement of the two types of probes in the horizontal plane and in the cross section differ in magnitude, but have very similar shape in overall distribution. Axial mean velocity components show especially wide differences around the slits and outer part of the swirl vanes within the range of X/R=2. Also, various turbulence intensities appear in a similar trend to axial mean velocity components within the range of X/R=2. The radial component of turbulence intensity around the slits and the outer part of swirl vanes above the range of X/R=2 has an opposite phenomenon. On the whole, the T-probe’s measurements appear smaller than the X-probe’s. This shows that the X-probe is better than the T-probe, especially on the swirling flow because it is much easier to use.     

Effects of coupling between electrodynamics and gasdynamics in open cycle disk type MHD generators

To study the effects of swirl and wake on open cycle disk generators operated with a heavy oil-air combustion gas, the effects of coupling between electric field and gas flow are analyzed. A three-dimensional potential equation and two-dimensional compressible flow equations are solved by a finite element method. Both velocity and thermal wakes induce large nonuniformities of potential distribution and degrade the generator performance. This is mainly due to the strong coupling between potential and temperature distributions. The velocity nonunivormity affects performance through thermal interaction. It is predicted that the electrical efficiency can reach 75% in large scale disks. Regular fluid nonuniformities given by sinusoidal waves cause a relatively small degradation of generator performance.     

Enhancement of heat transfer in a tube with regularly-spaced helical tape swirl generators

Influence of helical tapes inserted in a tube on heat transfer enhancement is studied experimentally. A helical tape is inserted in the tube with a view to generating swirl flow that helps to increase the heat transfer rate of the tube. The flow rate of the tube is considered in a range of Reynolds number between 2300 and 8800. The swirling flow devices consisting of: (1) the full-length helical tape with or without a centered-rod, and (2) the regularly-spaced helical tape, are inserted in the inner tube of a concentric tube heat exchanger. Hot air is passed through the inner tube whereas cold water is flowed in the annulus. The experimental data obtained are compared with those obtained from plain tubes of published data. Experimental results confirmed that the use of helical tapes leads to a higher heat transfer rate over the plain tube. The full-length helical tape with rod provides the highest heat transfer rate about 10% better than that without rod but it increased the pressure drop. To overcome this, different free-spacing ratio (s = L_s/L_h) of 0.5, 1.0, 1.5, and 2.0 were examined. It was found that the space ratio value should be about unity for Re < 4000. The regularly-spaced helical tape inserts at s = 0.5 yields the highest Nusselt number which is about 50% above the plain tube.     

气田采出水处理系统优化运行效果评价

长北天然气处理厂气田采出水处理系统自投运以来,在生产运行过程中存在采出水悬浮物含量高、油份处理效果差的状况,回注水中含油、悬浮物较高,回注泵故障频发,回注压力高。分析水质变差原因,同时对现有采出水处理系统进行分析,优化缓蚀剂加注方案,制定加药程序,引入新设备、新工艺提升采出水处理效果,使回注水含油量、悬浮物含量达到回注标准。     

Numerical investigation of effect of inlet swirl and total-pressure distortion on performance and stability of an axial transonic compressor

This paper represents numerical simulation of flow inside an axial transonic compressor subject to inlet flow distortion, to evaluate its effect on compressor performance and stability. Two types of inlet distortion, namely inlet swirl and total pressure distortion are investigated. To study the effect of combined distortion patterns, different combinations of inlet swirl and total pressure distortion are also studied. Results for cases with total pressure distortion indicate that hub radial distortion improves stability range of the compressor while tip radial distortion deteriorates it. An explanation for this observation is presented based on redistribution of flow parameters caused by distortion and the way it interacts with stall inception mechanisms in a transonic axial compressor. Results also show that while co-swirl patterns slightly improve stability range of the compressor, counter-swirl patterns diminish it. Study of combined distortion cases reveals that superimposition of effects of each individual pattern could predict the effect of a combined pattern on compressor’s performance within an accuracy of 1%. However, it is unable to predict the associated effect on compressor’s stability.     

2500m~3高炉热风炉生产准备实践

炼铁分公司高炉分厂2500m3高炉热风炉是八钢第一次采用硅质耐材的顶燃式热风炉,因此在耐材砌筑、烘炉及热风炉保温至高炉开炉阶段采取了相应的技术措施,使热风炉目前工作状况良好,送风温度1 200℃,炉皮没有出现发红及开裂现象,满足高炉高风温的需求。