Effect of Main Parameters on Cutting of the Pulsed Abrasive Water Jet

The relationship between abrasive concentration, length of oscillating chamber, standoff distance and cutting depth, erosion rate as well as cutting specific energy was investigated by experiments in the submerge and surface conditions. The cutting and erosion capabilities of the pre-mixed abrasive water jet and the pulsed abrasive water jet were analyzed in contrast. It is shown that the maximum cutting depth and erosion rate of the pulsed abrasive water jet are respectively 1.67,1.72 and 1.39, 1.47 than the pre-mixed abrasive water jet in submerge and surface conditions. These results attained from the research are useful to increase the cutting efficiency, decrease the energy ratio and expand the application domains of the abrasive water jet.     

Theoretically Investigation of Dynamic Characteristics of Spherical Bubble Collapse in Pulsed Abrasive Water Jet

This paper theoretically investigates the characteristics of cavitating bubbles in the pulsed abrasive water jet(PAWJ) and establishes the dynamic equations of cavitating bubbles. The effects of abrasive diameter and density on the spherical bubble collapse are also analyzed. It is found that the change of abrasive diameter rarely affects the bubble collapse when the abrasive diameter and density are small whereas the smaller abrasive greatly blocks the bubble collapse when the abrasive diameter and density are comparably big. It is also shown that when the abrasive density is increased, the fluid viscosity rises, and the kinetic energy of the abrasives near the collapsed bubble is enhanced and meanwhile the intensity of cavitating erosion is weakened.     

Experiments of the Self-excited Oscillation Pulsed Jet Nozzle

The self-excited oscillation pulsed jet nozzle which proposed makes the continuous jet transform into pulsed jet . Comparing with general continuous jet, the pulsed jet has a higher peak of pressure and larger volume of erosion , therefore it increases the effective distance off of the jet under the same conditions. The laboratory and industry experiments of the Self-excited oscillation pulsed jet nozzle are introduced in the report.     

Experimental Study on Cone Water Jet

The model of conical membrane atomization for cone water jet is presented. The atomizational ability and dust-laying effect for water jet are investigated experimentally. Some results are useful for dust-laying and fire-extinguishing researchers and designers.     

An Experimental Study of the Optimal Jet Position on Water Jet Assisted Drag Bit During Rock Cutting

The tests for the effects of jet position on drag bit cutting process were described. The influence of jet position on rock chips formed ahead of bit was analyzed. And the effects of cutting depth,bit velocity on bit force reductions were discussed. One of the most interesting results is that the water jet has the largest effect on drag bit forces when it is directed towards the center beneath drag bit.     

EXRERIMENTAL STUDY OF THE PULSED WATER-GAS JET

A new pulsed jet device is presented which can produce oscillatory pulsed wafergas jet. This device is used in the erasive experiment on the while sandbrick whose compressive resistance is 30 Mpa. The curves of the erasive effects of the oscillatory pulsed water-gas jet.the oscillatory pulsed jet and the ordinary jet are drawn in order to be compared.which are changed as the distances of the targets are changed. In addition the reason why the erasive effect of the new jet is superior to the other two jets is analyzed.     

Effect of Deflection Characters on Self oscillating Water Jet

The deflective mechanism of the oscillating water jet is analyzed and the effects of jet deflection on the self oscillating water jet are investigated. It is experimentally shown that the deflective angle may reach 9.53 degree, the pressure fluctuation is more intensive and more regular and the jet can efficiently eliminate the water cushion effect and increase the ability in cutting.     

Study on Hydrokinetics of the Unsubmerged Premixed Abrasive Water Jet

A mono-liquid model is established according to formative character of the premixed abrasive water jet. The hydraulic structure is analyzed by the model. The relationship that is obtained between the axial shaft line velocity and the forget distance by the law of conservation of momentum is verified with the experiment.     

苹果片气体射流冲击干燥工艺的优化

采用一种新型的气体射流冲击干燥技术,对切片厚度6～8mm的苹果片进行了干燥试验研究。在喷嘴直径为16mm,喷嘴气流速度为16.8m/s的条件下,得出苹果片气体射流冲击干燥处理的最佳工艺参数为:喷嘴出口气体温度70℃,喷嘴与苹果片最佳距离120mm,干燥盒宽度为200mm,物料堆积高度为35mm。     

The Grey Related Degree Analysis of the Cutting for the Premixed Abrasive Water Jet

The cutting property is studied with the grey theory and method for the premixed abrasive water jet.The relationship between the primary and secondary is obtained about the cutting specific energy influenced by pressure,the standoff distance,the abrasive concentration and transverse velocity.The guidance is provided for further research and pratical application.     

Mechanism analysis of permeability based on promoting coal matrix shrinkage by water jet

High pressure pulsed water jet (HPWJ) is a new technology of effectively improving coal seam permeability. However, the mechanism of increased permeability is not yet clear, which restricts the application of HPWJ in different coal seams. From the perspective of improving permeability by coal matrix shrinkage, the impelled dynamic equations is established based on analysis of coal dynamic effects by water jet. According to theoretical analysis of the stress state of coal matrix, it is concluded that HPWJ can promote coal matrix shrinkage, and the relationship equation between jet impact-coal matrix is derived. Besides, the gas seepage function in the coal slotted by the HPWJ is gained by using PM model, which provides theoretical support for generalizing the technology in the coal mine.     

Deoxidation Efficency Research of Jet Themral Dloxidation

In this papet,a new deoxidationmethod-jet thermal deoxidation of industrialfeedwater was presented,a preliminary theoretical anlysis of mechamism of deoxidation methed wasmade. Using this experimental method,we studied the deoxidation methed and checked the effect ofthe temperatare pressure fogging state and jet direction on the deoxidation efficiency.     

Ice Jet and Ice Preparation

An injection ice jet system has been studied and established.Through ice jet removing paint experiment,three parameters that influence removing efficiency such as flow,temperature,diameter are investigated.The experiment results come to the conclusion that ice jet can achieve removing paint in lower working pressure.Also a plan of preparing ice particles continuously has been put forward,and the analyses and calculations are done in terms of theory.     

射流器在离子交换树脂再生工艺中的应用探讨

针对常规离子交换树脂再生液配制工艺设备投资大、运行维护成本高的缺点,介绍了应用圆柱型混合管水—水射流器的优势,并对其工作原理、结构设计和主要参数的计算进行了讨论,利用流体力学知识解决了射流器应用的设计核心问题,形成了一套完整有效的应用射流器进行离子交换树脂再生液配制的工艺设计方案。结果显示,该设计方案在企业生产中应用,具有良好的经济效益。该设计方案对射流器在其他工艺领域的应用也具有一定的设计参考价值。     

Studies on the Oxidation of Weathered Coal with Nitric Acid

A raseach has been done on the possibility of producing nitriochumic acid fromweathered coal of Nantong,Sichuan,oxidised by nithic acid.The optimun reacting conditions,whichare found through the way of orthogonal experiment,are suggested as follows:concentration ofHON3 35%,rate of HON3 to coal 3.5,reacting take 15 min,and reaction temperature 369 K. Thecomposition of product is Wf 2. 91 %;Ag 14.06%;HAg 78.28%;Ng 1.62%.     

Indexes optimization of outburst forecast while a rock cross-cut coal is uncovered by pulsed water jet

To obtain the best outburst prediction index of rock cross-cut coal uncovering slotted by pulsed water jet,the effects of the rigidity coefficient’s measured value and the initial velocity of gas diffusion to the integrative indexes D and K are analyzed based on the dynamic evolution of coal crake field under water jet. Thus the integrative indexes D and K are excluded. A grey relation model of outburst prediction indexes(K1,S and P)from 7 coal mine’ rock cross-cut coal uncovering in Chongqing,Sichuan and Henan is set up. And the grey relation degrees of the 3 prediction indexes to outburst hazard are calculated by using grey relational analysis method. The results show that the outburst hazard can be more accurately reflected by the cuttings desorption index K1 when a cross-cut coal uncovering slotted by pulsed water jet,and it should be considered as the best outburst prediction index.     

Analysis on stress wave effect during the process ofrock breaking by pulsed jet

A mathematical model of rock breaking under pulsed jet is established by introducing the Johnson-Holmquist-Concrete constitutive relation and the smoothed particle hydrodynamics method. Based on this model, the formation, propagation and attenuation of stress wave during rock breaking by pulsed jet are simulated. The relations between pressure and time at different points on rock surface and the curve of peak stress wave versus distance to action spot are obtained. Destruction behaviors of rock under pulsed jet and effects on stress wave effect from jet velocity and lithology are studied according to the above calculation results, analysis results show that stress wave effect of pulsed jet acts locally and the peak stress wave shrinks sharply as the acting distance increases. The rock breaking mechanism of stress wave is tensile failure during the high speed process of load-unload. Power and effect range of stress wave is in high direct proportion with jet velocity. There is a threshold velocity before the macroscopic failure. Rocks of different lithologies have different destruction types under pulsed stress wave of pulsed jet. Destruction type of low strength rock like sandstone is crack propagation under the tensile stress during the high speed process of load-unload, while the destruction type of high strength brittle rocks like granite and limestone is vertical failure of stress concentration.     

气体射流冲击技术在果蔬干燥中的应用

干燥处理是果蔬加工的一项重要技术,气体射流冲击作为一种新型的干燥技术在果蔬干燥方面具有很强的优势。本文综述了目前果蔬干燥常用的技术方法及其优缺点,阐述了气体射流冲击干燥技术的原理、特点、影响因素和干燥工艺。与传统干燥方法相比较,气体射流冲击干燥技术具有对流换热系数大、干燥速度快、产品质量高、能耗低等优点,在果蔬干燥方面应用前景广阔。