分离热流对自毁装置安全性的影响

对自毁装置火工品在级间热分离过程中的安全性进行了研究。结果表明,热流对装有起爆药的电起爆器和装有猛炸药的柱形爆炸器和线形爆炸器会产生不同的影响,电起爆器在级间分离过程中有发生爆炸的可能,而装有猛炸药的柱形爆炸器和线形爆炸器不会发生爆炸。

大规模数据流统计中冷热流替换策略优化

对大规模数据流统计的问题进行了研究,针对大流统计的典型结构Elastic Sketch替换策略中存在的问题进行优化,优化策略解决了冷流被误判为热流插入重部的问题。针对重部中保存的不一定是最大流的问题进行优化,提出了基于最大值和组相连的替换策略,保证了存储在重部的一定是最大的流,提高了大流统计的精度,同时大大降低了热碰撞发生的概率。相比于传统的测量统计方法,在提高了测量精度的同时,减少了内存占用。

Effects of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification

In order to understand the effect of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification, a series of threedimensional numerical simulations were conducted by the finite-difference method. The results indicate that the stable flow is observed when the Marangoni number （Ma） is small; however, when the value of Ma increases and exceeds a threshold value, the stable steady flow transits to be unstable flow. As the height of the melt increases, the flow is enhanced at first and then gets weakened. As the width of gap decreases gradually, the strength of flow is enhanced. The approach of using axial magnetic field is an effective way to suppress the buoyant-thermocapillary convection. As the magnetic field strength increases, the inhibition is enhanced. The critical Marangoni number increases slightly with a greater melt height, a narrower width of gap, and a more strength of magnetic field.

A Novel Strategy for Simulating the Main Fractionator of Delayed Cokers by Separating the De-superheating Process

Delayed coking is an important process in refinery to convert heavy residue oils from crude distillation units （CDUs） and fluid catalytic cracking units （FCCUs） into dry gas, liquefied petroleum gas （LPG）, gasoline, die- sel, gas oils and cokes. The main fractionator, separating superheating reaction vapors from the coke drums into lighter oil products, involves a de-superheating section and a rectifying section, and couldn＇t be simulated as a whole column directly because of non-eouilibrium in the de-suoerheatine section. It is verv imoortant to correctlv simulate the main fractionator for operational parameter and energy-use optimization of delayed cokers. This paper discusses the principle of de-superheating processes, and then proposes a new simulation strategy. Some key issues such as composition prediction of the reaction vapors, selection of thermodynamic methods, estimation of tray efficiency, etc. are discussed. The proposed simulation approach is applied to two industrial delayed cokers with typical technological processes in a Chinese refinery by using PRO/II. The simulation results obtained are well consistent with the actual operation data, which indicates that the presented approach is suitable to simulate the main fraction- ators of delayed cokers or other distillation columns consisting of de-superheating sections and rectifying sections.

Improvements of drilling fluid processing for cable-suspended electromechanical drills

Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills with bottom-hole circulation are designed and explored. Used at present drilling fluid circulation systems are specified by very high fluid wastes during processing. Measurements in deep drilling projects in Antarctic and Greenland ice sheets showed that 25%-40% of the drilling fluid, pumped into the hole, is retrieved to the surface with cable and drill, and up to 45% of retrieved fluid goes to waste. This leads not only to increasing of the fluid consumption and cost of the project in general but also to severe contamination of air, surface and near-surface snow-firn layers at the drilling site. In order to reduce wastes and environmental impact, it is proposed to modify drilling fluid processing system by avoiding of evaporation and leakages of fluid as far as practicable. Drilling fluid is prepared and pumped into the hole according to predetermined program on semiautomatic mode, and volume and density of blended and pumped into the hole drilling fluid are measured continuously. Components of the drilling fluid are stored and mixed in the special closed containers equipped by pressure relief valves. Separation of drilling fluid from ice cuttings is carried out by two steps: firstly, fluid is separated with hydro extractor and then with thermal separator. To reduce the amount of removed drilling fluid with cable special squeezing collar is installed on the borehole mouth. All these arrangements are able to decrease drilling fluid wastes in many times.

Effects of Pulsation on Separated Flow and Heat Transfer in Enlarged Channel

Numerical results of three-dimensional separated flow and heat transfer in an enlarged rectangular channel are presented in this paper.The expansion ratio and aspect ratio of the channel are 2.0 and 16.0,respectively.Reynolds number of the flow is 200 and it is over the critical Reynolds number.Over the critical Reynolds number,the flow in the symmetric channel becomes asymmetric and deflects to one side of the walls.Effects of the pulsating fluctuation at the inlet upon the flow in the channel are investigated.It is clarified that the inlet flow with a pulsating fluctuation of Strouhal number 0.05 and 0.10 strongly affects on the flow in the channel,and heat transfer on the walls is enhanced,especially on the wall surface covered with long separation bubble.On the other hand,the pulsation of St=0.0125 oscillates the shear layer more weakly than that of St=0.05,0.10 and the enhancement of heat transfer is smaller,though some vortices are shed from the vicinity of the side wall near the reattachment region.The oscillation of the main flow calms down gradually as the Strouhal number of the pulsation increases over 0.10.The influence of pulsation of St=0.20 on the flow is restricted in the near downstream of the step,and heat transfer on the walls is almost similar to that of the steady flow in the channel.

Heat Transfer Effectiveness of Three-Fluid Separated Heat Pipe Exchanger

A heat transfer model for three-fluid separated heat pipe exchanger was analyzed,and the temperature transfer matrix for general three-fluid separated heat exchanger working in parallel-flow or counter-flow mode was obtained.It was found that the forms of temperature transfer matrix are similar for heat pipe rows with equal or different heat transfer surface area.Furthermore,by using the temperature transfer matrix of the heat pipe exchanger,the relationship between heat transfer effectiveness θ 1,θ 2 and M,NTU,U,Δt i were derived for the exchanger operating in parallel-flow or counter-flow mode,and a simple special example was adopted to demonstrate the correctness of these relationships.