8.2. Given the relationship between turbulence intensity and mean piston speed (

Question

8.2. Given the relationship between turbulence intensity and mean piston speed (Eq. (8.23)] and that the turbulence integral scale is z 0.2 x clearance height, use Eqs. (8.14) and (8.15) to estimate the following quantities for a spark-ignition engine with bore = stroke = 86 mm, r, = 9, at 1000 and 5000 rev/min and wide-open throttle: (a) Mean and maximum piston speed, maximum gas velocity through the inlet valve (see Prob. 8.1) (b) Turbulence intensity, integral length scale, micro length scale, and Kolmogorov length scale, all at TC

Explanation / Answer

Given that,

     bore ,d = stroke,l = 86 mm

    rc = 9 , at N= 1000 rpm and 5000 rpm

a) mean piston speed ,Vm = ?

       Vm = 2 X stroke X Rpm / 60

            = 2 X 86/1000 X 1000 / 60

            = 2.86 m/s

Maximum piston speed , Vmax = ?

    Vmax = S X 3.14 X N

             = 86/1000 x 3.14 X 1000 /60

            = 4.5 m/s

b)

Turbulence intensity = 0.16 X Re-1/8 X d

                            Re = ul / v = (1000 X 82 / 5000)-4/3

                                          = 0.029

     T.I = 0.02

     

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