OCR Text |
Show 0 10 -#*( Q » B)/ a( Lin° C Fig. 5. - Mp / < Z, as a function of ^ vj_+( Q+ B)/ CT^ and eL for p = 760 torr. 7. The Conditions for Ablation Which Accentuates Surface Irregularities As was previously mentioned, the heat transfer coefficient at points and ridges is appreciably greater than at an extended smooth surface. If a ridge is regarded approximately as a section of a circular cylinder, « , = 66l/ « , ( 19) is the equation giving the numerical value of the heat transfer coefficient at the ( ridge) boundary, where T, is in meal cm"' min" 1 deg" 1 if the wind velocity, u, is in m s" 1 and the radius of curvature, R, is in cm. For u = 3 m s~ , the following pairs of values occur: 16 |