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Electronic Instrumentation for Measuring Detonation in Spark And

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Electronic Instrumentation for Measuring Detonation in Spark And AN ABSTRACT OF TEE TEES IS OF for (Naine) (Degree) (Majr'r) Date Thesis presented-__Qa.iL-- T itle - .'42 _ _f.2W.0 -------------------------------------------------- Redacted for privacy Abstract Approved: ------------------ (Major Professor) Th. extreie1y transient nature of the mgtn. cn)n1tiOn roceec rsq.res th9t spocial intruiîtaticri be used to ittx1y the e.rociitoi ihezoitienn. Tho nethoda wKioh hwvo been used to sti.c1y 1ne propogation and cyli.rder pressure sra 1oacrbed and the 1iaitattorB cf the present istrw'ïmtRtion are pointed out, A r.c trpø cnCire irliuiCOEtor drro1ope in the laborntories of tho Stardard Oil Corpftny of California onployir the *noto-s;r1otion prino-tp).c is dAcribd. Thie engine indicator oonii5te essentially of a rnioto8trictivo nickel alloy red sur- rowed by two coilt of rire and hold fïrtt1'- agarist diaphrrn which is exposed to the oylincicr recure, To oie coil a voltße 13 r-i11od from a f1athliht b&tt.rjr. The seoon coil i5 C1ìCOt(d 'rouh a loti gain ar-:].tfior to the vertieal plMes of 1 cat'ode ray osoiUnraph. Tho cylinder preaure ii trans.t±ed to the rod end the longitudinal 3tre resu1tin changoß the r.ant1e pernability so that t ae is gorierated i th 8GCOI2J 0011 whiO) 16 directly nroportirnial fo rate of pressure ohene within the erine oylinder. OsoilloCrar8 XO presented bovin rete preesuro change va. tine diagrams of the combustion ?rOOeS hi n high speed Diosel engine, Ot1r asurent msde ou both Diesol eni3 aso1ino engines dth the "aneto-ttriotion enìine indicntor are ':i van, In addition to thu emïne jidioator several other cleotronic deyioec usad in itudyinC engine coution aro deeoribod cd illuatratod by photographs. The recent work of tho Gerai otor 1.esearch Corporation corre1atth f1at oropogation as ObSOZV6d by photographing onino coruetion at 5000 oioturos per second with the cylinder prooGures ti43aurod sLiuitan6ously hi r.a.do it posuiibl3 tø stud;ï f1ax'o propoatio: wiLthout the reod of a o8tly qu&rt windor cquiDpod cugini. The only requìroiint is that the prsuuro inuiostor be substentially inertialese and aocurto1y reproduoe the crltncivr prossure evon at high cpccdu rd with sever. detonation, The data preecnted tndioat that the ii,pieto-atriution origino indioator ful- fi1s theie reqiñrønents and in addition is oonveniont c oporate and is law in out. ELEG'rRONIJ INSTRUMTLPIoN FOR MEIASURING DBONAION IN SPARK AND CO1RESSION IGNITION NGINS by WILLIAM VINCTT HANLEY A TILSIS submitted to the OREGON STATE GOLLEGE in partial fulfillment of the requirements for the degree of MECFNICAL GINER June 1938 AP P1O VED Redacted for privacy Professor of Meohanloal Engineering In Charge of Major Redacted for privacy F Head of Department of Mechanical Engineering Redacted for privacy Chairman of School Graduate Committee Redacted for privacy Chairman of State o1lege Graduate ounoil A T The writer w1he8 to acknowledge the &s3iStanoe rendered by Mr. K. R. Edredge in designing the electrical equipment described in this thesis. TL..BLE OP C0NTTS Page I. Introduction ................................. 1-3 EI. Methods Used to Study the Combustion Process .. 4-10 III. Development of the Magneto-Striction Indicator. 11-25 tV. Calibration of the Magneto-Striction Indicator. 26-29 V. TyDical Measurements Made with the Magneto- Strioti on Indicator . ...... ..... .. ... .. .. 30-37 VI. Other Electronic Instrumentation Used to Study Combustion . o.. .... ........ .. 38-47 VII. Conclusions . ... ..... ...... ....... .. 48-49 VIII. Bibliography a . .. 1s . .. 50-52 I GI3S !'ig. 1. Circuit Used with Magneto-Striction Indicator. 15 Fig. 2. Magneto-StriatIon Cylinder Pressure Unit ..... 15 ?ig. 3. Magneto-Strictlon Injection Line Pressure Unit 1 :91ig. 4. First Magneto-Striction Pressure Unit ........ 17 :'ig. 5. Improved Magneto-Striction Pressure Indicator. 18 Pig. 6. Circuit Diagram 5" Cathode ay Oscillograph... 20 F'ig. 7. Supercharged Army Air Corps Gasoline Engine... 21 Fig. 8. Moving PictureViewer........................ 24 ?ig. 9. Balanced Pressure Unit ....................... 27 Fig. 10. Fairbanks-MorseDieselEngine................ 31 Fig. 11. Osclllograms Showing Effect of changas in Load 32 Fig. 12. Oscillograms Showing Effect of Changes in Cetane Number . .......... ..... .. 32 ig. 13. Waulcesha Conversion Diesel Engine ............ 39 Pig. 14. Miscellaneous Electronic Equipment Used inStudyingEngine Combustion................ 41 HLEOE!YRONIC INSTRD1NTkION ?OR 1IStJRING DETONA'ION IN SP.RK .LND COMPRESSION IGNITION ENGINES I. IN'i'RODU2ION Ever since the early work of Midgely, Boyd and Ricardo in which the phenomenon of detonation in Bpark ignition engineB was demonstrated, the desii of engineS an the development of fuels of high anti-knock value to minimize this objeotional phase of combustion have been important considerations. More recently detonation In high-speed Di9sel engines bas been recog- nized as a problem retarding the development of engines of 'nigh specific output for use in mobile equipment. In common with most engineering problems the solu- tion is largely a i.tter of sufficient interest and the development of suitable instrumentation to allow a study of the fundamentals involved. The design of Instru- mentation for studying engine detonation is largely a matter of making use of the electronic devices which have been developed within the past few years for radio, oommunioation8 und other electrical services. The greatest single development bas been the improved t;Tpes of vacuum tubes which are adaptable to many uses. .s an example of the developments in this field the oscillograph is typical. FIve years ago the osoillograpoommercially available cost several 2 thousand dollars and were large, cumbersome and incon- enient to use, and very limited in frequency response. lthough cathode ray oscillographs have been in use for cver ten years it has been only within the past five years that small portable osoillographs with high sensi- tivity and wide frequency range have been commercially available for less than $100. These recent developments In the field of elec- tronics have been brought about not by their application to the study of engine combustion, to be desoribed In the followIng sections, but by the vast amount of research work In connection with the development of the modern radio. The low cost of the el'ctronic equipment is the result of the mass troduction methods required to manufacture radios ut present prioes. Electronic devices for measuring the physical, chomical and mechanical pro- oeseS associated with engine combustion have not been adequately investigated due largely to the lack of under- standing of the function and application of such equip- ment and the reticence on the part of the average mechanical engineer to trust measurements de v.ith vacuum tubes. The followIng description of the application of eleotronic equipment to trie measurement of detonation and other combustion phenomena i11ustrt a number of cases in which the solution of the problem could not have been obtained by any Icnown mechanical measuring methods. II. METHODS USEDrO STUDY TH COMBUSTION PROSS wide variety of methods have been enìployed to study the combustion process within the engine cylinder. These are divided into two enera1 classes; measurement of flame propagation, and the measurement of pressure changes within the enïne cylinder. Measurement of ?lame Propagation L.mong the methods which have been used to Investi- gate the propagation of flame are the following: Sodium line reversal method of measuring temperature (20, 4, 11, 13), spectrosooDic analysis of radiation (6, 35), Sohijeren photograohy showing the flame movement by dif- ference In refraction of gases of different densities (8, 25), instantaneous sampling (29, 39), ionization gaps indicatlnp presence and location of flame (27, 3, 14), radiometrie measurement of flame temperature (9, 19), photoelectric detection of flame travel (22), and high- speed flame photography (12, 5, 23, 24). Measurement of ylinder Pressures These indirect methods of determining the progress of combustion have all yielded valuable Information, but since the primary objeot of the combustion of fuel In the cylinder is to develop pressure which may be con- verted to useful work on the engine piston, the more direct measurement of cylinaer presBure would normally be preferred, except that in the past Instrumentation hes not been available to indicate the extremely rapid pressure changes which oocur. Cylinder pressure changes at frequencies as high as 20,000 per second are known to exist, and the entire combustion process Is completed in a few micro-seconds thus rendering the problem of measurement exoeedinly difficult. Because of the need of an accurate and inertialess pressure Indicator, many attempts have been made to develop such an Instrument. Phe fol1owin brief summary includes descriptions of the more important and better-known types: Mechanical TyDes The earliest attempts at indicating cylinder pres- sures all consisted of transmitting the pressure through a diaDhragm or piston to some form of pencil or stylus bearing on a rotating drum. These mechanical indicators have been found unsatisfactory for indicating cylinder pressures in engines operating at high speed, although the Maihaic, Mader and Cambridge micro mechanical Indica- tors have been found reasonably satisfactory at low engine speeds. The De Juhasz samling valve indicator is another mechanical type which has been used with sorne ucoess on high-speed engines. With this unit the usual mechanical
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