THE CHEMiCAL WORLD THIS WEEK the translational motion of t h e bubbles in addition to t h a t resulting from their growth a n d collapse action. Quantitative d a t a relating b u b b l e size, population, a n d frequency to d i e heat transfer conditions w e r e presented.
Fluid F l o w Stressed As Aircraft Speeds Rise C&EN REPORTS: Heat Transfer and Fluid Mechanics Institute L O S A N G E L E S . — T h e importance of fluid flow, both compressible and n o n c o m p r e s sible, with the a d v a n c e in speeds of air craft and g u i d e d missiles was e m p h a s i z e d at t h e t h i r d H e a t Transfer and F l u i d Mechanics Institute, w h i c h m e t at the I n stitute of A e r o n a u t i c a l Sciences here, J u n e 28 t h r o u g h 30. Over 350 engineers a n d scientists a t t e n d e d t h e meeting, which w a s sponsored jointly by 11 technical societies and California universities. T w e n t y - t w o p a p e r s covering problems of cooling engines, particularly turbojet, ramjet, a n d rockets, w e r e p r e s e n t e d . Among three papers reporting contri butions to fundamental knowledge of t h e interrelationship of fluid flow a n d heat transfer w a s o n e by Robert G. Deissler of NACA Lewis Flight Propulsion L a b o r a tory, who discussed recent investigations of turbulent flow a n d heat transfer in smooth tubes, including the effects of vari able fluid properties. E q u a t i o n s , w h i c h h a d been derived analytically, to p r e d i c t radial velocity distributions for fully developed turbulent flow in smooth tubes both with
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a n d w i t h o u t heat transfer, were s u b stantiated in tests measuring over-all h e a t transfer coefficients a n d friction factors in tubes. A n e w method for determining the in fluence of variation o f physical properties on heat transfer in turbulent flow was de scribed by W . D. Rannie, California In stitute of Technology. The method does not separate t h e laminar sublayer and the buffer layer, but gives a single curve for the velocity profile w h i c h joLns the t u r b u lent core profile with a continuous veloc ity gradient. Recent developments in thie field of gas turbines h a v e revealed the n e e d for data on heat transfer in free-convection flow at very h i g h Grashof nuxnbers C 1012 to 10 1 *), a n d E . R. C . Eckert and Ύ. W. Jackson of N A C A Lewis Flight Propulsion Labora tory gave a n analysis of t h e turbulent free—convection boundary l a y e r on a flat plate. H e a t T r a n s f e r during Freezing An application of t h e electrical analog to t h e solution of problems in solidifica tion w a s presented b y F. E_ Rornie, Uni versity of California, and î^rank Kreith, Princeton University. It w a s pointed out that the differential equations describing the general process of solidification or melting include a nonline^ar boundary condition at the t r a v e l i n g solid-liquid interface. Mathematical difficulties resulting from this nonlineairity have resulted in existing solutions t o the solidification problems b e i n g restricted to those incorporating particular boundary conditions w h i c h eliminate the nonlinearity. T h e nonlinear boundary condition does not complicate the solution w h e n the solution is obtained by means o f an electrical analog to t h e thermal system*, according to Romie. Observers indicated that this study will b e of interest t o metallurgists as well as to the ice-making industry. Surface Boiling H e a t
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A photographic s t u d y of surface boiling heat transfer t o w a t e r with forced convection was s h o w n and described by Fred Gunther, California Institute of Technology. The h i g h speed, high resolution photographs showed t h e formation of bubbles, and the understanding of the beha vior of the bubbles of a boiling fluid is expected to shed new l i g h t on t h e design of high efficiency boileirs. The p h o t o graphic results indicated trmat the coolant velocity does not detach -vapor b u b b l e s from t h e heating surface at large subcooling. T h e attached bubbles slide d o w n stream during growth and collapse producing turbulence i n the sublayer from
CHEMICAL
Combustion E n g i n e e r i n g Problems Close attention of burner manufacturers in a t t e n d a n c e , as well as jet propulsion designers and other engineers interested in combustion problems, was directed to a series of p a p e r s related to this field. A. K. Oppenheim, Stanford University, discussed a graphical interpretation of t h e analysis of shock and combustion fronts a n d its application to t h e theory of d e tonation phenomena. Oppenheim explained t h a t a combustion zone developing into a detonation w a v e is idealized as a system consisting of two coexistent discontinuities, o n e of w h i c h is a shock front and t h e other a combustion front. An analysis of such a system was p r e sented arid t h e locus of states immediately b e h i n d t h e combustion zone consisting of t h e t w o fronts was described. O n this basis, it was shown that the r e markable stability of t h e detonation w a v e and the mechanical aspects leading to its development can be explained. In t h e course of t h e development of the detonation w a v e four modes of combustion w e r e distinguished, namely, weak deflagration, strong deflagration, weak detonation, a n d strong detonation. Rich hydrocarbon-air-nitrogen flames burning in t u b e s assume a cellular struct u r e in t h e absence of turbulence in t h e a p p r o a c h stream, according to G. H . Markstein, Cornell Aeronautical Laboratory. In work which was s u p p o r t e d by t h e Office of Air Research a n d Office of Naval Research, Markstein found t h a t this p h e n o m e n o n o c c u n e d in all hydrocarbons investigated except m e t h a n e . A general formula for skin friction including h e a t transfer to a flat plate w a s derived for a thin, t u r b u l e n t b o u n d a r y layer in compressible fluids b y E. R. Van Driest, N o r t h American Aviation, I n c . T h e p a p e r described t h e t u r b u l e n t b o u n dary layer for compressible fluids on a flat p l a t e with heat transfer. W h e n t h e b o u n d a r y layer is insulated, this general formula yields skin-friction coefficients higher t h a n t h o s e given by t h e Kânriân wall-property, compressible-fluid formula, b u t lower t h a n that given by t h e Karman incompressible fluid formula, according t o Van Driest. H e pointed out that when t h e plate is cooled, t h e skin-friction cofficients are generally higher t h a n they are for t h e insulated plates but remain lower t h a n the value for incompressible fluids. Rocket D e s i g n Attracting considerable attention b y those interested in rocket design was a paper describing a "superposition analysis of the turbulent boundary layer in an adverse pressure gradient, presented by D . Ross a n d J. M. Robertson, Pennsylvania
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THE CHEMICAL WORLD THIS WEEK special panel to study t h e problems of introducing private ownership of real property a n d self-government in t h e three communities housing t h e people w h o work in t h e plants a n d laboratories at Los Alamos, N . M., Hanford, Wash., a n d Oak Ridge, Term. Scurry is senior member of t h e Dallas law firm of Scurry, Scurry a n d Pace. T h e A E C will invite a group of m e n qualified in real estate management a n d municipal government to become m e m b e r s of t h e panel. Complete mem bership will b e announced upon accept ance of t h e invitations. T h e A E C h a s requested that the panel
State College. Consideration of the tur b u l e n c e processes involved in boundary layer flow leads to t h e concept that t h e flow conditions in t h e outer regions of t h e b o u n d a r y layer are governed, primar ily b y t h e space history of t h e flow, w h e r e a s t h e flow near t h e solid wall is controlled b y local phenomena. T h i s con cept, together with observations of t h e form of measured diffuser boundary layer profiles, leads to the development of a superposition method of analysis for t h e velocity distribution. Of interest ίο engineers working in t h e field of cooling towers a n d evaporative coolers w a s a p a p e r describing t h e cool ing of a freely-falling water d r o p , b y X. \V. Snyder, University of California. Cooling of a freely-falling w a t e r drop is characterized by b o u n d a r y conditions which vary with time. A complete d e scription of t h e heat transfer within a d r o p is complex inasmuch as t h e mixing within t h e d r o p is not d e s c n b a b l e , a n d t h e s h a p e of t h e d r o p is not of a regular type. In Snyder's studies, temperatures of fail ing 3 - , 4-, 5-. a n d 6-mm. w a t e r drops w e r e determined by a calorimetric tech n i q u e . F r o m the discussion following, it was evident that this paper is important to t h e water conservation measures b e i n g t a k e n b y Southern California industries, since t h e efficiency of the cooling towers to a large extent determines industrial w a t e r utilization. Louis G. D u n n , California Institute of Technology, w a s general c h a i r m a n for the meeting, a n d w a s assisted b y cochairman L . M . K. Boelter, University of California at L o s Angeles, a n d A. L. L o n d o n , Stan ford University 7 . Myron Tribus, Univer sity of California, was chairman of t h e papers committee, a n d J. C. Dillon, Uni versity of California, served as chairman of t h e p r o g r a m committee. T h e H e a t Transfer a n d F l u i d Mechanics Institute is sponsored by California Insti t u t e of Technology, Santa Clara Univer sity, Stanford University, University of California, a n d University of Southern California, together with t h e local sections of t h e American Institute of Chemical E n g i n e e r s , American Society of Civil E n g i n e e r s , American Society of Heating a n d Ventilating Engineers, Americar» So ciety of Mechanical Engineers, American Society of Refrigerating Engineers, and Institute of Aeronautical Sciences. T h e next m e e t i n g of t h e institute will b e h e l d at Stanford University' d u r i n g t h e latter p a r t of J u n e 1 9 5 1 . Persons inter ested in presenting papers at t h e next m e e t i n g should contact A. L . L o n d o n , c h a i r m a n of t h e 1951 institute a t Stan ford University, Stanford, Calif.
headed by Scurry study t h e problems of property ownership a n d government i n relation to the effects of moves toward these ends on t h e primary purposes oi the communities—providing housing a n d community facilities that will attract a n d hold t h e personnel required in the opera tion of plants a n d laboratories. It is also expected to give advice and recommenda tions as to how far a n d by what steps t h e A E C may go in this direction in t h e near future without jeopardy to the funda mental job of maintaining production of fissionable materials and creation of weapons designs.
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AUTOCLAVES
OOWTHERM SYSTEMS
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available fabrication drawings.
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T h e Atomic Energy Commission has an n o u n c e d that Richard G. Scurry of Dallas, Tex. ? has a c c e p t e d chairmanship of a V O L U M E
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1950
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