平板边界层内的流速分布实验

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1、平板边界层内的流速分布实验（一）.实验目的测定平板上离前缘某一定点处边界层内的流速分布及其厚度。（二）仪器设备吸入式风洞~大气压强计~温度计~微压计~U形测压管~平板模型~总压探针及三维坐标架。（三）实验原理1.边界层外为理想流体（总压P0=Pa和速度V无穷不变）。2.边界层内为实际流体（P0和ux都在变化，Po

2、.56.边界层厚度δ的定义：在外边界上的速度ux与来流速度V无穷相差1%的点，该点据平板壁面的垂直距离为边界层厚度）(四）数据处理（1）当x=150mm时，Re=2.031*10^5,可以认为是层流，当X=250mm时，Re=3.38*10^5,为紊流（2)在图一和图二中，X=150mm,实际曲线与紊流理论曲线更接近，因此为紊流在图二和图三中，X=250mm,实际曲线与紊流理论曲线更接近，因此为紊流(3)计算得X=150mm时，层流边界层为14.35mm,紊流边界层为2.125mm根据实验数据分析得实际边界层厚度约5.15

3、mm,接近紊流X=250mm时,层流边界层厚度为18.527mm,紊流边界层为3.92mm，实验得实际边界层厚度约6.80mm,接近紊流。（4）数据记录及分析如下表一.X为150mm的速度分布记录表NO坐标读数L(mm)边界层内距离y（mm)微压计读数Pa边界层内流速u(m/s)速度比u1/VU形管读数⊿h/0.3(mmH2O)边界层内流速u2(m/s)速度比u2/V理论层流速度u(m/s)层流速度比理论紊流速度u(m/s)紊流速度比100.45164.3214.7890.6925015.7800.7321.4400.06

4、713.7180.642211.45118.3617.2380.8073617.8620.8294.6110.21616.2140.759322.4582.2418.9410.8872519.3410.8987.6890.36017.4760.818433.4554.6820.1450.9431620.4710.95010.6100.49718.3520.859544.4537.8020.8470.9761021.1920.98413.3100.62319.0310.891655.4528.2421.2350.994821

5、.4270.99515.7260.73619.5900.917766.4526.4021.3090.997721.5431.00017.7920.83320.0680.939877.4525.8021.3330.999721.5431.00019.4450.91020.4850.959988.4525.0021.3651.000721.5431.00020.6200.96520.8570.9761099.4525.2821.3540.999721.5431.00021.2550.99521.1930.992表二X为250m

6、m时的速度分布记录表NO坐标读数L(mm)边界层内距离y(mm)微压计读数Pa边界层内流速u(m/s)速度比u1/VU形管读数h/0.3(mmH2O)边界层内流速u2(m/s)速度比u2/V理论层流速度u(m/s)层流速度比理论紊流速度u(m/s)紊流速度比100.45186.613.4420.6305415.1330.7091.4390.06713.7180.643211.45145.9215.8150.7414316.8530.7904.6090.21616.2140.760322.45115.9217.3580.81

7、33518.0010.8447.6860.36017.4760.819433.4590.2818.5760.8702818.9490.88810.6050.49718.3520.860544.4568.3219.5580.9172119.8510.93013.3040.62319.0310.892655.4548.9220.3870.9551520.5930.96515.7180.73719.5900.918766.4535.9620.9220.9801121.0730.98817.7830.83320.0680.9408

8、7921.3090.9607.4529.5621.1820.9930.99919.4350.91120.485988.4526.3221.3120.999821.4271.00420.6110.96620.8570.9771099.4525.621.3411.000821.4271.00421.2450