The pm-pose of this report is to describe work which has been carried out under the subject grant during the period from April 1, 1961, to October 1, 1961. Technical supervision and guidance of the work was provided by Mr. Seymour Lieblein, Chief, Flow Physics Branch, NASA Lewis Research Center, Cleveland, Ohio

Sparrow, E. M.

English

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Semi-.Annual Status  Report HI CROF I LH $ 
NASA Grant: MsG 137-81 
Radiation Heat Transfer 
Submitted byt E o  M e  Spamow 
Deparbent of Mechanical Engineering 
University of BBiPlnesota 
Minneapolis l L ,  Minnesota 
The puzgose of t h i s  report  is t o  describe work which has been carried out 
m d e r  the a b j e c t  grant during the period from April b, 1961, t o  October lo 
1%lo Technical supemleion and guidance of the m r k  was provided by Mr, Seymour 
Lieblein, Chief, Flow Physics Branch, NASA Lewis Researah Center, Cleveland, Ohio, 
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Radiant Absorption Charactieristics of Cavities 
Asalfiieal studies  have been carried out  t o  determine t h e  absorption 
chamcter i s t ics  of ssrrisus type3 of cavities w i t h  respect t o  radiant energy enter- 
i n g  the cavity from t he  out%ideo Three di f fe ren t  cavity shapes have thus far been 
considered: 
enclosure open a t  the topo 
apparent absorptivity, which is  the mtis of the energy absorlaed i n  the cavity to 
the t o t a l  radiation entering the cavity, 
the size of the cavity, on the actual  surface absorptivity, and i n  sane cases, on 
sone characteristic of the entering enexgy. 
(a) a v-shaped groove, (b) a rectangular groove, and (c) a spherical  
The f i n a l  I.esults kava been phrased i n  term of an 
The apparent absorptivity depends on 
For the v-groove and the rectangular groove, the study was carried through 
(a) radiation arr iving i n  a para l le l  f o r  -0 general types of incoming energy: 
ray bundle, (b) radiation d i f h s e l y  distributed i n  spaceo 
absorption results haw been obtained fo r  cavity surfaces which are e i t h e r  diffuse 
re f lec tors  or specular (mirror) reflectors., For the spherical enclosure, it was  
possible t o  obtain results fo r  an arbitrary spacial  d i s t f lbu t ion  of the incoming 
anergy, but this degree of generality was possible only for diffusely mf lec t ing  
surf aces 
For each situation, 
https://ntrs.nasa.gov/search.jsp?R=19620003750 2020-03-11T16:43:13+00:00Z
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Tks absorption studies f o r  the  aforementiuned cavi t ies  am complete, a i d  
the results are EOPI availableo Papers covering this work will be written. 
Radiating Hna 
A t  the request of Mr, Uebbeln, a detailed znalytical formla t ion  of the 
heat t sansfer  pmcsssea taking place i n  a general fin end tube space-vehicle 
radiator has been carfied out, 
hater discussed with menbere of Mr. Lieblein's Branch, 
wem delineated by the formulation and by the subsequent discussion, 
This formulation has been oral ly  presented and 
Several problem are= 
SpcifAc analyt ical  consideration has been giwen t o  par t icular  types of f i n  
and tube radiators, f o r  example, t o  a eadwich configuration i n  w h i c h  the fins 
are the covers o f t h e  sandwiah and the tubes a m  the meat, The equations governing 
the energy exchange by conduction and radiation h a w  been fonnulated, and numerlcal 
work w i l l  be undertaken during the  next phase of the project. I 
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Radiation Characteristics of Honeycomb Surface 
I n  connection w i t h  a space sirnuPator being designed a t  the Lewis Research 
Center, it is desined t o  know the radiation character is t ics  of a honeycomb surface 
which will be uaed t o  cover the walls of the simulator chamber, 
mdel appropriate t o  a typical element of the honeycomb has been formulated, and 
the equations which govern the energy trmsfer by radiation and conduction have 
been written, 
project, 
An analy t ica l  
Numerical solutions w i l l  be undertaken i n  the next phase of the 
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Experimental Studies 
The hemispheriual re f lec t iv i ty  of aluminum f o i l  was measured a t  the  mquest 
of Mro Lleblein, A aopy of a l e t te r  i n  which these t ea t s  are reported is 
attached, 
An instrument has been under development for  measuring the direct ional  
r e f l e c t i v i t y  of surfaceso Some of the featunta of the instrument are as follows: 
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A beam of blaok-body energy is directed at  the test surface, the angle between the 
incident beam and the surface normal being arbitrarily variable. 
reflected at a preselected angle i a  focused on a thennopile and recorded. 
The energy 
The 
device I s  so arranged that energy reflected a t  any arbitrary angle oan be measured. 
Various parts of the instrument have been fabrioated, and It is expected that the 
teat set-upwil l  soon be completed. 


Radiation Heat Transfer

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