1、Designation: G134 95 (Reapproved 2010)1G134 17Standard Test Method forErosion of Solid Materials by Cavitating Liquid Jet1This standard is issued under the fixed designation G134; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEUpdated Section 3 to reflect Terminology G4010b editorially in December 2010.1. Scope1.1 This test method covers a
3、test that can be used to compare the cavitation erosion resistance of solid materials.Asubmergedcavitating jet, issuing from a nozzle, impinges on a test specimen placed in its path so that cavities collapse on it, thereby causingerosion. The test is carried out under specified conditions in a speci
4、fied liquid, usually water. This test method can also be usedto compare the cavitation erosion capability of various liquids.1.2 This test method specifies the nozzle and nozzle holder shape and size, the specimen size and its method of mounting, andthe minimum test chamber size. Procedures are desc
5、ribed for selecting the standoff distance and one of several standard testconditions. Deviation from some of these conditions is permitted where appropriate and if properly documented. Guidance is givenon setting up a suitable apparatus, test and reporting procedures, and the precautions to be taken
6、. Standard reference materials arespecified; these must be used to verify the operation of the facility and to define the normalized erosion resistance of othermaterials.1.3 Two types of tests are encompassed, one using test liquids which can be run to waste, for example, tap water, and the otherusi
7、ng liquids which must be recirculated, for example, reagent water or various oils. Slightly different test circuits are required foreach type.1.4 This test method provides an alternative to Test Method G32. In that method, cavitation is induced by vibrating a submergedspecimen at high frequency (20
8、kHz) with a specified amplitude. In the present method, cavitation is generated in a flowing systemso that both the jet velocity and the downstream pressure (which causes the bubble collapse) can be varied independently.1.5 The values stated in SI units are to be regarded as standard. No other units
9、 of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determin
10、e theapplicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issu
11、edby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A276A276/A276M Specification for Stainless Steel Bars and ShapesB160 Specification for Nickel Rod and BarB211 Specification for Aluminum and Aluminum-Alloy Rolled or Cold Finished
12、 Bar, Rod, and WireD1193 Specification for Reagent WaterE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodG32 Test Method for Cavitation Erosion Using Vibratory ApparatusG40 Terminology Relating to Wear and ErosionG73 Test Method for Liquid Impingement
13、Erosion Using Rotating Apparatus1 This test method is under the jurisdiction of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by Solidsand Liquids.Current edition approved Dec. 1, 2010Nov. 1, 2017. Published December 2010December 2017. Orig
14、inally approved in 1995. Last previous edition approved in 20062010as G13495(2006).G134 95 (2010)1. DOI: 10.1520/G0134-95R10E01.10.1520/G0134-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsv
15、olume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to ad
16、equately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
17、ocken, PA 19428-2959. United States12.2 ASTM Adjuncts:Manufacturing Drawings of the Apparatus33. Terminology3.1 See Terminology G40 for definitions of terms relating to cavitation erosion. For convenience, definitions of some importantterms used in this test method are reproduced below.3.2 Definitio
18、ns:3.2.1 cavitation, nthe formation and subsequent collapse, within a liquid, of cavities or bubbles that contain vapor or a mixtureof vapor and gas.3.2.1.1 DiscussionCavitation originates from a local decrease in hydrostatic pressure in the liquid, usually produced by motion of the liquid (see flow
19、cavitation) or of a solid boundary (see vibratory cavitation). It is distinguished in this way from boiling, which originates froman increase in liquid temperature.3.2.1.2 DiscussionThe term cavitation, by itself, should not be used to denote the damage or erosion of a solid surface that can be caus
20、ed by it; thiseffect of cavitation is termed cavitation damage or cavitation erosion. To erode a solid surface, bubbles or cavities must collapseon or near that surface. G403.2.2 cavitation erosion, nprogressive loss of original material from a solid surface due to continued exposure to cavitation.G
21、403.2.3 cumulative erosion, nin cavitation and impingement erosion, the total amount of material lost from a solid surfaceduring all exposure periods since it was first exposed to cavitation or impingement as a newly-finished surface. (More specificterms that may be used are cumulative mass loss, cu
22、mulative volume loss, or cumulative mean depth of erosion. See alsocumulative erosion-time curve.)3.2.3.1 DiscussionUnless otherwise indicated by the context, it is implied that the conditions of cavitation or impingement have remained the samethroughout all exposure periods, with no intermediate re
23、finishing of the surface. G403.2.4 cumulative erosion rate, nthe cumulative erosion at a specified point in an erosion test divided by the correspondingcumulative exposure duration; that is, the slope of a line from the origin to the specified point on the cumulative erosion-time curve.(Synonym:aver
24、age erosion rate) G403.2.5 cumulative erosion-time curve, nin cavitation and impingement erosion, a plot of cumulative erosion versus cumulativeexposure duration, usually determined by periodic interruption of the test and weighing of the specimen. This is the primary recordof an erosion test. Most
25、other characteristics, such as the incubation period, maximum erosion rate, terminal erosion rate, anderosion rate-time curve, are derived from it. G403.2.6 flow cavitation, ncavitation caused by a decrease in local pressure induced by changes in velocity of a flowing liquid.Typically, this may be c
26、aused by flow around an obstacle or through a constriction, or relative to a blade or foil.Acavitation cloudor “cavitating wake” generally trails from some point adjacent to the obstacle or constriction to some distance downstream, thebubbles being formed at one place and collapsing at another. G403
27、.2.7 incubation period, nin cavitation and impingement erosion, the initial stage of the erosion rate-time pattern during whichthe erosion rate is zero or negligible compared to later stages.Also, the exposure duration associated with this stage. (Quantitativelyit is sometimes defined as the interce
28、pt on the time or exposure axis, of a straight line extension of the maximum-slope portionof the cumulative erosion-time curve.) G403.2.8 maximum erosion rate, nin cavitation and liquid impingement erosion, the maximum instantaneous erosion rate in a testthat exhibits such a maximum followed by decr
29、easing erosion rates. (See also erosion rate-time pattern.)3.2.8.1 Discussion3 Available from ASTM International Headquarters. Order Adjunct No. ADJG0134.G134 172Occurrence of such a maximum is typical of many cavitation and liquid impingement tests. In some instances, it occurs as aninstantaneous m
30、aximum, in others as a steady-state maximum which persists for some time. G403.2.9 normalized erosion resistance, Ne, nin cavitation and liquid impingement erosion, a measure of the erosion resistanceof a test material relative to that of a specified reference material, calculated by dividing the vo
31、lume loss rate of the referencematerial by that of the test material, when both are similarly tested and similarly analyzed. By “similarly analyzed,” it is meantthat the two erosion rates must be determined for corresponding portions of the erosion rate time pattern; for instance, themaximum erosion
32、 rate or the terminal erosion rate.3.2.9.1 DiscussionA recommended complete wording has the form, “The normalized erosion resistance of (test material) relative to (referencematerial) based on (criterion of data analysis) is (numerical value).” G403.2.10 normalized incubation resistance, No, nthe no
33、minal incubation period of a test material, divided by the nominalincubation period of a specified reference material similarly tested and similarly analyzed. (See also normalized erosionresistance.) G403.2.11 terminal erosion rate, nin cavitation or liquid impingement erosion, the final steady-stat
34、e erosion rate that is reached(or appears to be approached asymptotically) after the erosion rate has declined from its maximum value. (See also terminalperiod and erosion rate-time pattern.) G403.3 Definitions of Terms Specific to This Standard:3.3.1 cavitating jet, na continuous liquid jet (usuall
35、y submerged) in which cavitation is induced by the nozzle design orsometimes by a center body. See also jet cavitation.3.3.2 cavitation number, a dimensionless number that measures the tendency for cavitation to occur in a flowing stream ofliquid, and that, for the purpose of this test method, is de
36、fined by the following equation. All pressures are absolute.5pd 2p v!12 V2(1)where:pv = vapor pressure,pd = static pressure in the downstream chamber,V = jet velocity, and = liquid density.3.3.2.1 For liquid flow through any orifice:12 V25pu 2p d (2)where:pu = upstream pressure.3.3.2.2 For erosion t
37、esting by this test method, the cavitating flow in the nozzle is choked, so that the downstream pressure, asseen by the flow, is equal to the vapor pressure. The cavitation number thus reduces to:5pd 2pvpu 2pv(3)5pd 2pvpu 2pd(3)which for many liquids and at many temperatures can be approximated by:5
38、 pdpu(4)sincepupdpv (5)3.3.3 jet cavitation, nthe cavitation generated in the vortices which travel in sequence singly or in clouds in the shear layeraround a submerged jet. It can be amplified by the nozzle design so that vortices form in the vena contracta region inside the nozzle.3.3.4 stand-off
39、distance, nin this test method, the distance between the inlet edge of the nozzle and the target face of thespecimen. It is thus defined because the location and shape of the inlet edge determine the location of the vena contracta and theinitiation of cavitation.G134 1733.3.5 tangent erosion rate, n
40、the slope of a straight line drawn through the origin and tangent to the knee of the cumulativeerosion-time curve, when the shape of that curve has the characteristic S-shape pattern that permits this. In such cases, the tangenterosion rate also represents the maximum cumulative erosion rate exhibit
41、ed during the test.3.3.6 vena contracta, nthe smallest locally occurring diameter of the main flow of a fluid after it enters into a nozzle or orificefrom a larger conduit or a reservoir. At this point the main or primary flow is detached from the solid boundaries, and vortices orrecirculating secon
42、dary flow patterns are formed in the intervening space.4. Summary of Test Method4.1 This test method produces a submerged cavitating jet which impinges upon a stationary specimen, also submerged, causingcavitation bubbles to collapse on that specimen and thereby to erode it.This test method generall
43、y utilizes a commercially availablepositive displacement pump fitted with a hydraulic accumulator to damp out pulsations. The pump delivers test liquid through asmall sharp-entry cylindrical-bore nozzle, which discharges a jet of liquid into a chamber at a controlled pressure. Cavitation startsin th
44、e vena contracta region of the jet within the length of the nozzle; it is stabilized by the cylindrical bore and it emerges,appearing to the eye as a cloud which is visible around the submerged liquid jet. A button type specimen is placed in the path ofthe jet at a specified stand-off distance from
45、the entry edge of the nozzle. Cavitation bubbles collapse on the specimen, thus causingerosion. Both the upstream and the downstream chamber pressures and the temperature of the discharging liquid must be controlledand monitored. The test specimen is weighed accurately before testing begins and agai
46、n during periodic interruptions of the test,in order to obtain a history of mass loss versus time (which is not linear).Appropriate interpretation of the cumulative erosion-timecurve derived from these measurements permits comparisons to be drawn between different materials, different test condition
47、s, orbetween different liquids.Atypical test rig can be built using a 2.5-kW pump capable of producing 21-MPa pressure. The standardnozzle bore diameter is 0.4 mm, but this may be changed if required for specialized tests.5. Significance and Use5.1 This test method may be used to estimate the relati
48、ve resistances of materials to cavitation erosion, as may be encounteredfor instance in pumps, hydraulic turbines, valves, hydraulic dynamometers and couplings, bearings, diesel engine cylinder liners,ship propellers, hydrofoils, internal flow passages, and various components of fluid power systems
49、or fuel systems of dieselengines. It can also be used to compare erosion produced by different liquids under the conditions simulated by the test. Its generalapplications are similar to those of Test Method G32.5.2 In this test method cavitation is generated in a flowing system. Both the velocity of flow which causes the formation ofcavities and the chamber pressure in which they collapse can be changed easily and independently, so it is possible to study theeffects of various parameters separately. Cavitation conditions can be controlled ea
