The flow rate of water through a tapered straight horizontal pipe fitting is 5 m/s. The diameter at the entrance is 0.7 m and is reduced by a factor of 0.6 at the exit. If the gauge pressure at the entrance is 350 kPa and drops by 50 Pa, the horizontal thrust on the fitting is,

Respuesta :

Answer:

The  value is   [tex]F_t =  76024 \  N[/tex]  

Explanation:

From the question we are told that

  The  flow rate is  [tex]v_1 =  5 \  m/s[/tex]

   The  entrance diameter is  [tex]d =  0.7 \  m[/tex]

  The  exit diameter is evaluated as [tex]d_e  =  0.6  *  0.7 =  0.42  \  m[/tex]

   The entrance gauge pressure is  [tex]P_g =  350 \  kPa =  350*10^{3} \  Pa[/tex]

    The  droped gauge  pressure is  [tex]P_d =  50 \  kPa =  50*10^{3} \  Pa[/tex]

 The presure at the exist is evaluated as  [tex]P_e =(350  -    50 ) \  kPa =  300*10^{3} \  Pa[/tex]

Generally the entrance cross-sectional area is mathematically represented as

     [tex]A =  \pi \frac{d^2}{4}[/tex]

     [tex]A = 3.142 \frac{0.7^2}{4}[/tex]

      [tex]A =0.385 \ m^2[/tex]

Generally the exit  cross-sectional area is mathematically represented as

        [tex]A_e =  \pi \frac{d_e^2}{4}[/tex]

     [tex]A_e = 3.142 \frac{0.42^2}{4}[/tex]

      [tex]A_e =0.139\ m^2[/tex]

Generally from the continuity equation

    [tex]v_1 * A  =  v_2 * A_e[/tex]

=>  [tex]v_2  =  \frac{v_1 * A}{A_e}[/tex]

=>  [tex]v_2  =  \frac{5 * 0.385}{0.139}[/tex]

=>  [tex]v_2  =  13.8 m/s [/tex]

Generally the net force in horizontal axis is equivalent to the net momentum change in the horizontal direction

So

     [tex]P_g *  A +  F_t - P_e *  A_e  =  P_d [ A_e * v_2^2 -  A* v_1^2][/tex]

Here  [tex]F_t[/tex] is the horizontal thrust on the fitting

So  

        [tex]350*10^{3} * 0.385  +  F_t -0.385  *  0.139  =  50*10^{3} [ 0.385* 13.8^2 -  0.385* 5^2][/tex]