流體力學
張國強吳家鳴編
習題答案
1-1 ρ = 8 kg/m3,v = 0.125 m3/kg,p = 0.684 mpa
1-2 m = 0.075 kg,v = 0.878 m3
1-3 k = 3 mpa
1-4 等溫:k = 0.1 mpa,絕熱:k = 0.14 mpa,等壓:αv = 0.00336 k-1
1-5 t = 212.1 n .m
1-61-7 p = 128.6 w
1-8 h = 3 mm
done
2-1 ,
2-2 幫浦吸水管入口:p = 116 kpa,冷凝器中:p = 20 kpa
2-3 h ≈ 340 m
2-4 ,p0、z0為液球表面某一點處的壓強和垂直座標;特別地,在無重力的外層空間,等壓面為球面。
2-5 p = 0.97p0:h = 256 m,t = 0.97t0:h = 1129 m
2-6 α ≤ 30o
2-7 pa - pb = 9963 pa
2-8 f = 2150 n
2-9 ,;,
2-10 h > 2.7 m
2-11 圓柱:d ≥ 0.1 m,圓球:r ≥ 0.072 m
2-12 d = 0.057 m
2-13 x = 0.25 m
2-14 1) p = 109800 pa;2) a = g;3) a = 6.1 g。g為重力加速度
2-15 a = 1.96 m/s2
2-16 1);2) ω = 14.0 rad/s;3) v = 0.025 m3,h = 0.090 m
2-17 n = 12
done
3-1 ,
3-2 a y = b x
3-3 x2 + y2 = c 2
3-4 ,
3-5 ,
3-6 uz = -x z + z2/2
3-7 qv = 0.241 m3/s, qm = 241 kg/s,v = 21.3 m/s
3-8 qvmax = 0.0177 m3/s,vmax = 2.25 m/s
3-9 ,,;,,
3-10
done
3-11 ~ 3-15
done
4-1 ,為有旋流動
4-24-34-4 ,,;,,
;,,4-5 v1 = 8.04 m/s,v8 = 6.98 m/s
4-6 qm =3.54 g/s
4-74-8 1) v = 5.94 m/s,pmin = 62763 pa;2) h2』 ≤ 9.76 m
4-9 qm = 439 kg/s
4-10 m = 3.09 kg
4-11 f = 11.70 n,θ = 30o
4-12 v2 = 38.26 m/s,p2 = 95.8 kpa,t2 = 270 k,ρ2= 1.232 kg/m3
4-13
4-14 t = 0.348 n. m,p = 63 w,ρ2 = ρ1 = 1.154 kg/m3,p2 = 1.011 mpa,t2 = 305 k
4-15 p = 31.6 kw
done
5-15-2 取n、d和ρ為基本變數,有
或5-3 取n、qv和h為基本變數(注意h為壓強單位),有
或5-4 取d、ρ和v為基本變數,有
或5-5 取l、v和ρ為基本變數,有
和5-6 取τw、y和ρ為基本變數,有 (式中,)
5-7 取d、n和p為基本變數,有
或5-8 fo = 1.5 kn
5-9 σ= 0.0843, δz = 1.64 m
5-10 n = 2353 r/min,t = 0.933×10-3 nm
5-11 取u、d和ρ為基本變數,有
或done
6-1 l ≤ 0.565 m
6-2 x = 2 m:δ = 0.017 m;x = 5 m:δ ≈ 0.12 m
6-3 ,,,
6-4 fd = 19.0 n
6-5 x = 21 mm
6-6 層流:δmax = 5.0 mm,fd f = 0.664 n,紊流:δmax = 23.3 mm,fd f = 2.33 n
6-7 命題成立,對於非定常流動也成立。
6-8 1) x* = 0.161 m;2) p = 71.8 kw
6-9 δ1 = 0.55 mm, u1 = 1.97 m/s,δp = 320 pa
6-10 f = 1540 hz
6-11 fx = 173.6 n,fz = 43.3 n;θ = 14o
6-12 d 6.265 m
done
7-1 d < 12.7 mm
7-2 λ = 0.021
7-3 層流:δp2/δp1 = 16;紊流:δp2/δp1 = 32
7-4 層流:α = 2,β = 4/3;紊流1/7律:α = 1.06,β = 1.02
7-5 δpf = 4.96 mpa
7-6 qv = 0.101 m3/s,h0 = 8.4 m
7-7 d 0.381 m
7-8 qv1 = 0.035 m3/s,qv 2 = 0.010 m3/s;hf = 90965 pa
7-9 qv = 0.0666 m3/s
7-10 p = 773.5 w
7-11 z 5.5 m
7-12 1) v = 4.97 m/s,qv = 0.562 l/s,v2/2 = 12.3 j/kg;
2)v = 29.4 m/s,qv = 0.208 l/s,v2/2 = 432 j/kg
7-13 ξ = 0.5625, pj = 5060 pa
7-14 d2 = 510 mm
7-15 串連:pf = 53.5 kpa;並連:pf = 1.17 kpa
7-16 c = 1123 m/s,δp = 5.615 mpa;實際中不發生水擊
7-17 1) px = -91414 pa;2) px = 687777 pa
7-18 截面收縮係數ε = 0.64,流速係數φ= 0.97,流量係數μ = 0.62,區域性損失係數ξ = 0.066
7-19 t = 503 s
done
8-1 u 58.9 m/s = 212 km/h
8-2 按可壓縮流計算:u = 216.8 m/s,按不可壓流計算:u = 204.2 m/s;δu/u = 5.8%
8-3 假設飛彈表面狀態與駐點的相同:u = 686 m/s;實際上:u = 715 m/s
8-4 w = 284 kw/kg
8-5 qm = 2.856 kg/s
8-6 u = 551 m/s,p = 124 kpa,qm = 54.4 kg/s
8-7 1) 採用縮放噴管(p2 < p*);
2) p* = 623 kpa,t* = 477.5 k,ρ* = 4.546 kg/m3,u* = 438 m/s;
3)t2 = 385 k,ρ2 = 2.66 kg/m3,u2 = 614.6 m/s
8-8 ma = 2.236,u = 760 m/s,t = 1.64 s
8-9 a* = 1.74 cm2,a2 = 2.21 cm2,u2 = 614.6 m/s;a = 2.04 cm2,u = 278.1 m/s
done
9-1 m, m/s, m/s, m/s
9-2 m3/s
9-3 d0 = 0.208 m, m3/s
9-4 m3/s, m/s,umax = u0 = 10 m/s
9-5 1) m,2) m3/s,3) m3/s
9-6 m/s, oc,y = -3 m
9-7 v2 = 0.18 m/s, oc,y = -4.25 m
9-8 m,s = 1.915 m
9-9 m, mg/l
9-10 在射流主體段
, 在射流起始段
, done
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