流体力学习题答案

1、.流 体 力 学张国强 吴家鸣 编习题答案1-1 = 8 kg/m3，v = 0.125 m3/kg，p = 0.684 MPa1-2 m = 0.075 kg，V = 0.878 m31-3 K = 3 MPa1-4 等温：K = 0.1 MPa，绝热：K = 0.14 MPa，等压：aV = 0.00336 K-11-5 T = 212.1 N .m1-61-7 P = 128.6 W1-8 h = 3 mmdone2-1 ，2-2 泵吸水管入口：p = 116 kPa，冷凝器中：p = 20 kPa2-3 H 340 m2-4 ，p0、z0为液球表面某一点处的压强和垂直坐标；特别地，在无

2、重力的外层空间，等压面为球面。2-5 p = 0.97p0：H = 256 m，T = 0.97T0：H = 1129 m2-6 a 30o2-7 pA - pB = 9963 Pa2-8 F = 2150 N2-9 ，；，2-10 H > 2.7 m2-11 圆柱：D 0.1 m，圆球：R 0.072 m2-12 D = 0.057 m2-13 x = 0.25 m2-14 1) p = 109800 Pa；2) a = g；3) a = 6.1 g。g为重力加速度2-15 a = 1.96 m/s22-16 1) ；2) = 14.0 rad/s；3) V = 0.025 m3，h

3、= 0.090 m2-17 n = 12done3-1 ，3-2 a y = b x3-3 x2 + y2 = C 23-4 ，3-5 ，3-6 uz = -x z + z2/23-7 qV = 0.241 m3/s， qm = 241 kg/s，v = 21.3 m/s3-8 qVmax = 0.0177 m3/s，vmax = 2.25 m/s3-9 ，；，3-10done3-11 3-15done4-1 ，为有旋流动4-24-34-4 ，；，；，4-5 v1 = 8.04 m/s，v8 = 6.98 m/s4-6 qm =3.54 g/s4-74-8 1) v = 5.94 m/s，pm

4、in = 62763 Pa；2)h2 9.76 m4-9 qm = 439 kg/s4-10 m = 3.09 kg4-11 F = 11.70 N， = 30o4-12 v2 = 38.26 m/s，p2 = 95.8 kPa，T2 = 270 K，r2 = 1.232 kg/m34-134-14 T = 0.348 N. m，P = 63 W，r2 = r1 = 1.154 kg/m3，p2 = 1.011 MPa，T2 = 305 K4-15 P = 31.6 kWdone5-15-2 取n、D和为基本变量，有 或 5-3 取n、qV和H为基本变量（注意H为压强单位），有 或 5-4 取

5、D、和v为基本变量，有 或 5-5 取l、v和为基本变量，有 和 5-6 取w、y和为基本变量，有 （式中，）5-7 取d、n和p为基本变量，有 或 5-8 Fo = 1.5 kN5-9 s = 0.0843, z = 1.64 m5-10 n = 2353 r/min，T = 0.933×10-3 Nm5-11 取u、D和为基本变量，有 或 done6-1 L 0.565 m6-2 x = 2 m： = 0.017 m；x = 5 m： 0.12 m6-3 ，6-4 FD = 19.0 N6-5 x = 21 mm6-6 层流：max = 5.0 mm，FD f = 0.664 N

6、，紊流：max = 23.3 mm，FD f = 2.33 N6-7 命题成立，对于非定常流动也成立。6-8 1) x* = 0.161 m；2) P = 71.8 kW6-9 1 = 0.55 mm， U1 = 1.97 m/s，p = 320 Pa6-10 f = 1540 Hz6-11 Fx = 173.6 N，Fz = 43.3 N； = 14o6-12 d ³ 6.265 mdone7-1 d < 12.7 mm7-2 = 0.0217-3 层流：p2/p1 = 16；紊流：p2/p1 = 327-4 层流：a = 2，b = 4/3；紊流1/7律：a = 1.06，

7、b = 1.027-5 pf = 4.96 MPa7-6 qV = 0.101 m3/s，H0 = 8.4 m7-7 d ³ 0.381 m7-8 qV1 = 0.035 m3/s，qV 2 = 0.010 m3/s；hf = 90965 Pa7-9 qV = 0.0666 m3/s7-10 P = 773.5 W7-11 z £ 5.5 m7-12 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/kg7-13 = 0.5625， Dpj =

8、 5060 Pa7-14 d2 = 510 mm7-15 串连：Dpf = 53.5 kPa；并连：Dpf = 1.17 kPa7-16 c = 1123 m/s，p = 5.615 MPa；实际中不发生水击7-17 1) px = -91414 Pa；2) px = 687777 Pa7-18 截面收缩系数 = 0.64，流速系数f = 0.97，流量系数 = 0.62，局部损失系数 = 0.0667-19 t = 503 sdone8-1 u £ 58.9 m/s = 212 km/h8-2 按可压缩流计算：u = 216.8 m/s，按不可压流计算：u = 204.2 m/s；

9、u/u = 5.8%8-3 假设导弹表面状态与驻点的相同：u = 686 m/s；实际上：u = 715 m/s8-4 w = 284 kW/kg8-5 qm = 2.856 kg/s8-6 u = 551 m/s，p = 124 kPa，qm = 54.4 kg/s8-7 1) 采用缩放喷管(p2 < p*)；2) p* = 623 kPa，T* = 477.5 K，* = 4.546 kg/m3，u* = 438 m/s；3）T2 = 385 K，2 = 2.66 kg/m3，u2 = 614.6 m/s8-8 Ma = 2.236，u = 760 m/s，t = 1.64 s8-9 A* = 1.74 cm2，A2 = 2.21 cm2，u2 = 614.6 m/s；A = 2.04 cm2，u = 278.1 m/sdone9-1m， m/s，m/s，m/s9-2m3/s9-3d0 = 0.208 m， m3/s9-4 m3