OCR Text |
Show The boundary between ablation which accentuates and ablation which reduces surface irregularities is given by dM/ d< 3TL = 0. For a melting surface, which will be considered first, it follows from Equation ( 15) that a XL prs L\ + 0,623 rw pcp , ) - ( , 0,623 rw vo H i! » o Ftp ) ] - . ( 20) Here it is assumed that Q+ B, whose value may be freely chosen for the calculation, is independent of d. . Because ablation which promotes surface irregularities requires that - dM/ dflT, < 0, this is possible only when the equivalent temperature of the air, / v| + ( G- 623T / pc ) p , determined using rw , is less than that for saturated air at 0° C, • 9k in ° C F i g . 6. Domains with - dM/ d l'L < 0 for p = 525 t o r r , - 100 meal cm" 2 min" 1 - Q+ B - 400 meal cm min- 1 and # L - 50 meal cm" 2 min" 1 deg" 1 18 |