流体力学课后习题答案--wdp

流体力学课后习题答案大连交通大学机械工程学院机械电子教研中心1第二章【2－6】解：选一微圆环rrdrudF2drrurdFdM322043322DDudrruM【2－7】解：22110vuuvv33102.124.014.0108.04.0vvsmv187.0NvvAuF73.3108.0187.04.0100014.03101第五章【5－4】解：PagLppAB5.57581.92.01075.066.1800cos2气液－2smgppguABA33.262max气gpgugpBA0202max＋伯努利方程：smuv94.212.1maxskgAvqm143.194.212.0466.12【5－9】解：选控制体如图选坐标系列伯努利方程1－1，2－2gvH222ghv22设水箱对水的作用力F’列X方向动量定理：F’02242gHgHdF’gHd22水箱受力F与F’是作用力与反作用力gHdF22方向向左【5－10】解：设平面对射流的作用力xF3slqqqvvv24123612动量定理vqvqFvvx022cos1122sin0vqvqvv假设smvvv3021211224sin21vvqq30NFx46.456Fx为射流对平板的作用力方向朝右Fx=456.46N【5－11】解：列控制体如图4假设小车静止（坐标建立在小车上）则入口速度v+u质量流量uvA设小车对射流的力F’沿X方向列动量定理：F’sin0uvuvAsin2uvAF射流对小车的力sin2uvAF功率uuvAuFP22sinsin【5－12】解【1】叶片静止控制体如图设叶片对射流的作用力F’X方向动量定理：5F’uAuuAuuAucos2cos2KNNuAu256.5525645cos18.1941.01000cos122射流对叶片的作用力F=5.256（KN）方向朝右【2】若叶片以12m/s的速度后退，将坐标取在叶片上，认为叶片静止则射流速度（u-v）设三处速度相同，质量分半。F’45cos1128.191.041000cos1222vuAKNN82.07.815射流对叶片的作用力F=0.82（KN）方向朝右第七章【7－1】解：smdqvv274.1101041010422323850100085.0mkgd＝水232012741011010274.142dvRe层流gvlRf220502.064eRPaghfp346288502274.110101000502.0226【7－2】解：假设层流222322642dlvuvdlRvdlpe（也可用层流流量公式做）SPalvpdu144.06.163205.017691322200016.0900144.0u232050000016.005.06.1eR是层流假设是正确的【7－4】解：水水水水水－＝－＝hggpghsmdqvv5659.01.0436001642222smvv26.2421列伯努利方程：Rgvgpgvgp2222222111gvvgph22221gvgvvhR22121222121＋－＝－＝＝令水水54.0理论值：5625.01221AA7【7－5】解：1zhgpA21zzgpB列A,B伯努利方程gvdgvgvgpgvgpzBBBBAAA212222222BAvvgvdlgvzzzhzAA22222112gvdlgvhAA2222331.0【7－6】解：hp水水银－smdqvv12.205.04360015422列伯努利方程A,Bgvgvdh22122水水水银－642.005.08.00285.012.281.92100002.0100013600222dlvgh水水水银－【7－7】解：84212225222gqdldqgdlgvdlhvv278225gqdlhv原原＝86.9822151gqdlhv原后＝6.98222522gqdlhv＝后2221276.9vvqq＝vvqq5963.01vvqq4037.025222521dqdqvv＝原4583.05963.04037.0221252vvqqdd＝原8555.04583.05112ddcmd33.518555.0602【7－8】解：gqdlgvdlhv221512111182gqdlhv2225228gqdlhv223531815251212ddqqvvsmddqqvv3251212566.0smddqqvv325131356.1【7－9】解：（1）hhH9gvgvdlgvdl222232333322222232322302.010002.01.0100025.0vvv32265.1vv23322321144265.14dvdvdv1219.0265.1vv1319.0vvgvdlgvdlgvdlH219.0222122222144421111smN04.31SLq9.231.0404.32（2）gvdlgvdlgvdlH2222444422222211111112132dlgvsmldgv506.2321111SLsmvdq7.190197.043121【7－10】解：串联：smdqvv19.101.0408.042211smdqvv55.24222水头损失mdvdvglgvdgvd8.54522222212122221110并联：gvdgvd22222211222121dvdv122vvvqdvdv211221442smddqvv533.144221221mgvdh99.112121第八章【8－1】解：流量系数598.0281.9201.041094.2224gHAqcvd968.022.1232yHxcv618.0968.0598.0vdcccc0672.0112vc【8－2】解：流速系数yyxcv22224yyHcxv112222224HycHcxvv当2Hy时，x有极大值Hcxv【8－3】解：选控制体如图设挡板对射流冲击力F’沿x方向动量定理：－Fcvvq0smqFvvc704.99001029.2203pcvvc2pvccv2102p9704.0450009002704.9vcpAcqdc2728.002.04101029.2223pAqccd12752.09704.0728.0vdcccccvc110619.0112vcc