水射流全套教学课件英文版

1、1 Water Jet Technology -Fundamentals and Applications 32 Hours The course for graduate, undergraduate students and senior engineers majored in Petroleum Engineering, Mechanical ENGG. and other Mining Engineering What do U think about a selective course? 2 Why Should We Learn This Subject ? Because i

2、t is closely concerned to petroleum ENG. In oil well drilling, we use water jet; In oil production, we use water jet; In our daily life, we also make use of WJ. But these are not enough, we have additional reasons to learn this subject: WJT has now been and so developed that it has created a large i

3、ndependent industrial sector aimed for cleaning and cutting, such as cleaning in chemical industry, rock breaking in mining and road building, cutting in machining. In recent years, WJT got ever increasing new applications in petroleum ENG, such as hole drilling in oil formation, cleaning of perfora

4、ted holes to recover oil production, etc. 3 Objectives of the Course 1) To provide the fundamental mechanics and principles in water jet technology 2) To give some insight into the power of WJ through instances of application 3) To be acquainted with current development of WJT 4) To create a kind of

5、 environment for students to speak English, and provide a working vocabulary in the area of WJT 4 Materials and Dictionaries Academic background After learning of Text book: Fluid Jet Technology Fundamentals and Applications Reference material: 水射流技术与应用，沈忠厚等水射流技术与应用，沈忠厚等 On associated web sites Long

6、man dictionary of contemporary English An English-Chinese dictionary of technology 5 The Methodology 1.Attending class, take notes and pay more attention to main theory, principles, etc. 2.Reading text book and study new words appeared in the text 3.Making oral presentations in class - to get 20 poi

7、nts 4.Do home works (20 points for total 4 times) 5.Final test (60 points) 6 The Time Schedule Lect.ContentsHours 1Introduction to Fluid Jet Technology 3 2Fluid Mechanics of Jet System4 3Advanced jet technology6 4Mechanism of WJ Cutting - Infl.of Basic Jet Parameters 4 5Abrasive Water Jets 5 6Applic

8、ations in oil well drilling Engineering4 7Applications in Petroleum Engineering4 8Discussions and review 2 9Final test 7 Ch. 1 Introduction to WJT ROAD MAP FOR CHAPTER 1: 1 WJ Technology and its Basic Components 2 Historical Development 3 Water Jet Classifications 4 Features of WJT 5 Environmental I

9、mpact andPretreatment of Water 6 Examples of Application 7 Review For 34 hours 8 1. WJT and Basic Components in WJS 1.1 Definition of a Jet: A kind of fluid flow ejected from an orifice, a kerf or a nozzle to a larger space. A high-velocity fluid stream forced under pressure out of a small-diameter

10、opening or nozzle Can anyone give us some examples of jet in daily life? 9 1. WJT and Basic Components in WJS 1.2 Definition of Water jet Technology WJT is a growing technology branch regarding water jet cutting,cleaning and mining etc, and it covers a considerable community of knowledge concerning

11、(1) the generation of high pressure water, (2) the production of desired jet, and (3) improvement of work efficiency and safety, and so forth. 10 1. WJT and Basic Components in WJS 1.3 A Water Jet System generally consists of pumps or intensifier, pipe and joints, control valves, jet nozzles/gun, an

12、d other assistant and control parts such as movement system, a catcher and a table, and safeguard etc. System Design that includes calculation of Pr and Qfr, nozzle selection, the selection of pipeline, joints and valves etc, ensures a WJS to work safely and efficiently. 11 (1) Pump-2 types of pumps

13、 Triplex plunger pump, motor or diesel driven, for P 100Hydraulic mining Medium35-7038-150Plunger pumps Tube cleaning, mining applications High70-14010-120 Plunger pumps, Intensifiers Tube cleaning, cutting, mining applications Very High140-4204-10Intensifiers Industrial Cutting And no conta-minatio

14、n to the meat 38 Cutting of Board(s) Pressure:140-300 Mpa Flow rate:1-2 gpm Cutting nozzle are generally made of artificial crystal,most typically sapphire or ruby Jet diameter is normally 0.1-0.3 mm qNo selective cutting qNo harmful dust 39 Getting the harder part out of the parent material qSelect

15、ive cutting qNo damage to the valuable diamond 40 Rock Cutting The Millennium Arch (of granite) in UMR,USA cut with water jet Never blunt cutter Abrasive sometimes is added to the water 5-10%(V) 41 42 Turbine Blades or Vane Making by Jet Cutting With computer control, WJ can perform with high degree

16、 of precision 43 Intricate Contour Making No dust, but disposal of water is necessary No effect on the metallurgical phase 44 No dust, so no hazards for manufacturing of harmful material 45 Machining Turning, Deburring and Surface finishing 46 Manufacturing of Special Parts No special tools or mould

17、s are needed 47 Water Jet Carving 48 Floor Carving 49 Ceramic tiles cutting for making geometric forms 50 Glass Grinding 51 Ice particles as abrasive in water jet cleaning and cutting Ice particles may be generated in pipe line No contamination to cut materials No need of post disposal of abrasive 5

18、2 Well Drilling Pressure:50MPa Flow rate:10 l/S 53 Ship Surface Cleaning to descale marine creatures and rust 35-70 MPa 54 PipeCleaning Pressure:35-140 MPa Flow rate: 10-40 gpm No damage to the pipe, and the descaled debris being carried out by the water simultaneously. 55 Homework for lecture 1 Sum

19、mary work for the first lecture including the following main points ( about 500 words in English) 1. Definition of water jet technology ? 2. Components of WJ system. 3. Based on different factors, make a list of types of water jets and their main applications. 4. Advantages and backwards of WJT 56 C

20、hapt.1 review -True or false judgment I.The jets presently used for practical applications can be grouped within the three categories: continuous, pulsed, and cavitating. ( ) II.For most industrial applications, the mixture of water and fluid additive is substantially better than the “water-only” je

21、t. ( ) III. In safety and training, it is sufficient to simply put a person to be trained with an experienced operator for a period of time. ( ) 57 Chapt. 1 review -Filling the blank I.Based on pressure and flow capacity, there are two primary types of high pressure pumps: 1) pl- -; 2) in- . II.For

22、jet cutting,drilling or cleaning a typical system is composed of the following items: 1) por I- ,2) h-and j- , 3) vand r- , 4) n- , and sometimes 5) s- and 6 ) catcher . 58 Chapt. 1 review -Oral presentation I.What can WJ be used in industry for ? II.How are the pressure and flow rate when WJ is app

23、lied in cleaning, cutting. III. Why are intensifiers generally used in cutting ? IV. Why is the flow rate generally large enough in water jet cleaning ? Give a example. 59 Oral presentation To describe the characteristics of jet velocity profile according to the division of jet regions. To compare a

24、 submerged jet with a non submerged one based on the property of continuous free jet. To tell the difference between such pressures as instantaneous pressure and average pressure; and between stagnation pressure, static and dynamic pressures. 60 How to write a reasoning composition Generally contain

25、 an Introduction, Development and Conclusion. 1.Propose a point of view first; 2.Then give 2 or 3 examples of supports; 3. write your conclusions. 61 What requirements should be met for a good upstream flow condition ? 1)Absence of bend and radial flow in (10-50) 0D the length to the nozzle, or (10-

26、14) 0D if a smoother (a grid like honeycomb) is used. 2)Large diameter (at least 5 times Id of the nozzle ) 3)Symmetric, circular cross section 4)Good surface finish: achieve hydraulically smooth state right or false choice 62 2.For a jet used for cutting, Leach 2) length of straight exit section L=

27、(24)d0; 3) entry diameter D1=(510) d0 right or false ? 63 right or false ? There can exist three kinds of pressure resulted from jetting. The first is the stagnation pressure converted from jet velocity when the flow is completely stopped; The second can be water hammer pressure, which is produced b

28、y shock waves in a slug of water when it impact with solid surface. The third would be cavitating pressure exerted by micro-jets at the collapse of cavitating bubbles. 64 Lecture 2 Basic mechanics in jetting system For 4 hours 65 Basic mechanics in jetting system 1.Features of non-submerged jet flow

29、 2.Velocity profiles of submerged jet 3.Considerations for jet system design 4.Fluid mechanics in jet flow 5.Basic fluid dynamics of jetting system 6.Review and Home work 66 1.General Features of Non-submerged Continuous Jet Flow 67 1.General Features of Non-submerged Continuous Jet Flow As approach

30、ing downstream in air, water jet will dynamically entrain the surrounding air so that it tends to atomize and spread with its velocity slowing down gradually. Characteristics: 1) Atomization 2) Long core region and jetting distance versus submerged jet 68 1.General Features of Non-submerged Continuo

31、us Jet Flow According to V-profile characteristics, jet flow is divided into: a) initial region or core region, b)transient region c)essential region Or into: a) Developing zone b) Developed zone-essential section nc dx)1000( 69 2.Features of Velocity Profiles of Submerged Continuous Free Jet virtua

32、l Geometric self-similarity of the flow velocity in essential section essential initial transient 70 (1) Initial Region /Potential Core Definition: the section where velocity the jet centerline remains homogeneous. Characteristics: (a) Due to Entraining surrounding liquid, jet flow gets wider, and t

33、he area of potential flow with common V 0 becomes thinner and thinner and finally disappears. (b) For a round jet, potential core is typically a tapered one. 71 (1) Initial Region /Potential Core For a finely manufactured nozzle under good upstream flow conditions, the length of initial core of a su

34、bmerged round jet is generally 3-8 times of D0. Or else, it may extremely be 0. Compared with that in non-submerged jet ! 72 (2)Transient section: Definition: the region between core region and essential region, where flow is turbulent but not full developed turbulent. (3) Essential region (Develope

35、d zone ): Definition: The zone of jet in the downstream of transient zone, where jet velocities attenuate self-similarly. 2.Features of Velocity Profiles of Submerged Continuous Free Jet How is a flow called a self-similar flow ? 73 Velocity Distribution on Different Cross-sections of Submerged Cont

36、inuous WJ Velocity distribution varies at different standoff distance. Lx ry 74 Self-similarity in the Developed Zone of Submerged Continuous Jet Flow Velocities of the flow coincide with one standard distribution curve or are expressed in one form of equation. Lx ry 75 Centerline Velocity of Submer

37、ged Jet In initial region: In essential region: L = standoff distance off the nozzle exit LC= length of core region C0 LLVVc C LL 1 L Vc 76 Axial Mean Velocity Profile in Essential Region =r/(L-L0) Similarity of axial mean velocity 77 Radial Mean Velocity Profile Similarity of radial mean velocity W

38、hy so discrete ? 78 3. Considerations for jet system design 3.1 For continuous jet cutting 3.2 For specific application 3.3 Cavitating jet generation 3.4 Pulsed jet generation 79 3. Considerations for Jet System Design Function of Nozzle Basic function of a nozzle is converting the potential energy

39、of high pressure fluid into the kinetic energy of high velocity flow of the jet. The nozzle contraction ratio (dn/Di)2 is generally so small that nozzle exit flow velocity is quite uniform across whole cross section and that the turbulence intensity of flow in nozzle exit section is also suppressed

40、to a great extent. 80 Though jet tends to spread and slow by nature, it can remain more coherent and more effective through improvements in the phases: upstream flow condition nozzle design addition of some polymers 3.1 For Continuous Jet Cutting 81 Good Upstream Flow Conditions It means a fully dev

41、eloped, stable flow created when a feeding pipe meets the requirements: 1)Absence of bend and radial flow in the length of (10- 50) ID to the nozzle, or (10-14) ID if a smoother (a grid like honeycomb) is used. 2)Large diameter (at least 5 times dn) 3)Symmetric, circular cross section 4)Good surface

42、 finish: achieve hydraulically smooth state 3.1 For Continuous Jet Cutting 82 Nozzle design 1950s Roses study suggested that nozzle should be avoiding roughness and abrupt discontinuity of flow. 1960s Farmer experimentally suggested the importance of following streamline design. 1964, Leach 2) L=(24

43、)dn; 3) D1=(510) dn 3.1 For continuous jet cutting 83 3.1 For continuous jet cutting 3.1 For continueous jet cutting 84 3.1 For continuous jet cutting 3.1 For continueous jet cutting 85 Two functions of Additive polymer in jet system I.Friction Reduction: to reduce friction in pipe line so as to get

44、 higher jet pressure at fixed pump pressure. 3.1 For Continuous Jet Cutting II.Improving Jetting: to make the jet smoother and stronger so as to jet farther 86 For cutting and drilling with small diameters (1d034.5MPa), the L But in jet techn., d2/d1 0.447 Water jet 108 How to get a true “C” of a no

45、zzle? (4) )(1 683. 2 (5) 4 1 2 21 2 2 d d PP dQ QCQa Based on theories: Determining of Discharge Coefficient 109 In testing C of a nozzle, there are some musts: 1)Make sure there is a uniform entry flow condition; 2)give a small pressure increment; if it is the first run, then begin with Pn= 0. 3)Wh

46、en the flow has got steady,Measure the Qa and the corresponding Pn accurately; 4)Calculate Qideal and C with Eq. (4), (5); Determining of Discharge Coefficient 110 5)Mark the point in Pn-C coordinates plane with the calculated C and Pn, and connect the last two points with a line. If the line interv

47、al becomes horizontal, the last C will be the true one and stop the test, or else if the C continue to drop, then go to step (2) to continue a next run of the measurement. Identification of discharge coefficient 111 Good Finish Q - flow rate in l/min; D - tubing ID in mm; Re- Reynolds no. of the pip

48、e flow, above expression is valid for Re lying in 4000-100000; Basic Fluid Dynamics of Jetting System 116 Homework assignment 1: Composition Topic: Continuous Free water Jet Flow Contents: 1.Definitions for free continuous water jet, submerged water jet and non-submerged water jet. 2.Characteristics

49、 of non-submerged water jet. 3.Division of flow field of a submerged continuous free water jet and features of the core region and essential region. 4.The reason for the existence of the core region flow and essential flow. 117 Chapter 3: Review 1 1.Whats cavitation ? cavitation is the phenomenon of

50、 cavity generations of the air, water vapor or nothing/vacuum in flow field due to pressure drop. 2.Whats cavitating jet ? a jet in which the cavitation is artificially introduced or modulated to increase jet impact erosion capability. 118 Review 1 3. Cavitating jet generally experiences three phase

51、s: 1) Incipiency of cavitating; 2) Growth of bubbles; 3) Collapse of bubbles and generation of micro-jets 119 Review 1 4. True or false selection A) Cavitation happens only in liquid. On any occasion, it will never appear in the air or solid B) Cavitation results from the local pressure drop, and is

52、 generally found in the flow regions where strong turbulence and vortex intensity exists. C) Cavitation is a dynamic phenomenon; There wont be cavitation in a laminar flow. 120 Review 1 5. Identify the cavitation modes: 1) Fixed cavitation 2) rear flow cavitation 3) swirling cavitation 4) shear flow

53、 cavitation 5) resonating flow cavitation 121 Review 1 5. Identify the cavitation modes: 1) Fixed cavitation 2) rear flow cavitation 3) swirling cavitation 4) shear flow cavitation 5) resonating flow cavitation 5 . 03 . 0/ j vdfS Requirement preferable for vortices combination and growth: a) Helmhol

54、tz resonating chamber b) organ- pipe c) self- resonating It is called Strouhal number 122 Review 1 6. Give a interpretation (翻译,解释)of the following definition and analyze the cavitation tendency in dependence on the right hand parameters. When the K is less than 0.5, the jet would cavitate 2 2 j va

55、V pp K 123 Review 1 7. True or false choice (1) the lower the ambient pressure, the easier the cavitation; (2) the higher the temperature, the easier the cavitation; (3) the higher the relative velocity of the jet, the easier the cavitation 124 (4) Gas content , the number of bubble and the area of

56、the cavitating region , but the intensity of the collapse violence of individual bubble (5)Surface intensity will inhibit cavitation. Review 1 125 Review 2 Explain the functions of polymer additives on jet cutting Micro-mechanism linear structure and the aggregates of water reduce the entraining of

57、surrounding fluid Macro-mechanismmacrostructure entrains less surrounding fluid Bombardment of macromolecules on target material Why do some polymers have no effect on jet performance at extremely high pressure jetting ? 126 Chapter 3 Advanced Jet Characteristics -Cavitating, polymer solution and st

58、ar-shaped jets for 4 hours 127 Road Map of Chapter 3 1. Cavitating jet 2. Polymer solution jet 3. Star-shaped jet 128 1. Cavitating Jet 1.1 Definition and general description of cavitation 1.2 Cavitation incipiency modes 1.3 Cavitation number and parameter effects 1.4 Study methods of cavitating jet

59、 1.5 Effect characteristics of Cavitation 1.6 General observations on cavitation erosion 129 1.1 Definition and General Description of Cavitation 1)Definition:Defined simply by phenomena, cavitation is the generation and collapse of air/water vapor/vacant bubbles in flow field. In the process, viole

60、nt acoustic sound is produced. When liquid is heated to its boiling state or the pressure decreased below its saturation vapor pressure, dissolved gas and vapor in the liquid will separate out and thus bubbles appear. If the process is resulted from temperature rise, it is usually called “ boiling”;