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Question 8.5: What is the skin-friction coefficient for a turbulent bounda......

What is the skin-friction coefficient for a turbulent boundary layer on a flat plate, when M_e=2.5, \operatorname{Re}_x=6.142 \times 10^6, and T_w=3.0 T_e ?

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For these calculations,

F_c=2.056(\text { see Table 8.4) }

and

F_{\mathrm{Re}}=0.1729(\text { see Table 8.5) }

Thus,

\mathrm{Re}_x F_{\mathrm{Re}}=1.062 \times 10^6

Using Table 8.6, we obtain

F_c C_f=0.0035

so that

C_f=1.70 \times 10^{-3}

\text { TABLE 8.4 Values of } F_{\mathrm{c}} \text { as a Function of } M_{\mathrm{e}} \text { and } T_w / T_{\mathrm{e}}
M_e
\frac{T_w}{T_{\mathrm{e}}} 0.0 1.0 2.0 3.0 4.0 5.0 6.0
0.05 0.3743 0.4036 0.4884 0.6222 0.7999 1.0184 1.2759
0.10 0.4331 0.4625 0.5477 0.6829 0.8628 1.0842 1.3451
0.20 0.5236 0.5530 0.6388 0.7756 0.9584 1.1836 1.4491
0.30 0.5989 0.6283 0.7145 0.8523 1.0370 1.2649 1.5337
0.40 0.6662 0.6957 0.7821 0.9208 1.1069 1.3370 1.6083
0.50 0.7286 0.7580 0.8446 0.9839 1.1713 1.4031 1.6767
0.60 0.7873 0.8168 0.9036 1.0434 1.2318 1.4651 1.7405
0.80 0.8972 0.9267 1.0137 1.1544 1.3445 1.5802 1.8589
1.00 1.0000 1.0295 1.1167 1.2581 1.4494 1.6871 1.9684
2.00 1.4571 1.4867 1.5744 1.7176 1.9130 2.1572 2.4472
3.00 1.8660 1.8956 1.9836 2.1278 2.3254 2.5733 2.8687
4.00 2.2500 2.2796 2.3678 2.5126 2.7117 2.9621 3.2611
5.00 2.6180 2.6477 2.7359 2.8812 3.0813 3.3336 3.6355
6.00 2.9747 3.0044 3.0927 3.2384 3.4393 3.6930 3.9971
8.00 3.6642 3.6938 3.7823 3.9284 4.1305 4.3863 4.6937
10.00 4.3311 4.3608 4.4493 4.5958 4.7986 5.0559 5.3657

Source: Spalding and Chi (1964).

\text { TABLE 8.5 Values of } F_{\mathrm{Re}} \text { as a Function of } M_{\mathrm{e}} \text { and } T_w / T_{\mathrm{e}}
M_e
\frac{T_w}{T_{\mathrm{e}}} 0.0 1.0 2.0 3.0 4.0 5.0 6.0
0.05 221.0540 232.6437 256.5708 278.2309 292.7413 300.8139 304.3061
0.10 68.9263 73.0824 82.3611 91.2557 97.6992 101.7158 103.9093
0.20 20.4777 22.0029 25.4203 28.9242 31.6618 33.5409 34.7210
0.30 9.8486 10.6532 12.5022 14.4793 16.0970 17.2649 18.0465
0.40 5.7938 6.2960 7.4742 8.7703 9.8686 10.6889 11.2618
0.50 3.8127 4.1588 4.9812 5.9072 6.7120 7.3304 7.7745
0.60 2.6969 2.9499 3.5588 4.2576 4.8783 5.3658 5.7246
0.80 1.5487 1.7015 2.0759 2.5183 2.9247 3.2556 3.5076
1.00 1.0000 1.1023 1.3562 1.6631 1.9526 2.1946 2.3840
2.00 0.2471 0.2748 0.3463 0.4385 0.5326 0.6178 0.6903
3.00 0.1061 0.1185 0.1512 0.1947 0.2410 0.2849 0.3239
4.00 0.0576 0.0645 0.0829 0.1079 0.1352 0.1620 0.1865
5.00 0.0356 0.0400 0.0516 0.0677 0.0856 0.1036 0.1204
6.00 0.0240 0.0269 0.0349 0.0460 0.0586 0.0715 0.0834
8.00 0.0127 0.0143 0.0187 0.0248 0.0320 0.0394 0.0466
10.00 0.0078 0.0087 0.0114 0.0153 0.0198 0.0246 0.0294
\text { TABLE 8.6 Values of } F_c C_f \text { as a Function of } F_{\mathrm{Re}} \operatorname{Re}_{\mathrm{x}}
F_c C_f F_{\mathrm{Re}} \mathrm{Re}_{\mathrm{x}} F_c C_f F_{\mathrm{Re}} \mathrm{Re}_{\mathrm{x}}
 0.0010 5.758 \times 10^{10}  0.0055 8.697 \times 10^4
0.0015 4.610 \times 10^8 0.0060 5.679 \times 10^4
0.0020 4.651 \times 10^7 0.0065 3.901 \times 10^4
0.0025 9.340 \times 10^6 0.0070 2.796 \times 10^4
0.0030 2.778 \times 10^6 0.0075 2.078 \times 10^4
0.0035 1.062 \times 10^6 0.0080 1.592 \times 10^4
0.0040 4.828 \times 10^5 0.0085 1.251 \times 10^4
0.0045 2.492 \times 10^5 0.0090 1.006 \times 10^4
0.0050 1.417 \times 10^5

Source: Spalding and Chi (1964).

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