Shock tube test time limitation due to turbulentwall boundary layer

Shock tube test time limitation due to the premature arrival of the contact surface is analytically investigated for wholly turbulent-wall boundary layers The results are compared with those for wholly laminar-wall boundary layers It is found that, for a given shock Mach number Ms, the maximum possible test time (in a long shock tube) varies as d 6//4p co1/4 and d2p CD for the turbulent and laminar cases, respectively (d = tube diameter, p oo = initial pressure) For 3 ^ 5, whereas the laminar theory applies, roughly, for dpm ~ 1 (d is in inches; pm is in centimeters of mercury) When dp » 5, turbulent theory for both air and argon indicates test times of about one-half to one-fourth the ideal value for xs/d = 45 to 150, respectively (xs = length of low-pressure section) Higher values of dp » result in more test time When dpm ~ 0 5, laminar theory indicates about one-half ideal test time for xs/d ~ 100 Lower dpm reduces test time Working curves are presented for more accurate estimates of test time in specific cases Boundary-layer closure occurs, in long shock tubes, when Ms < 1 2 and Ms < 3 for laminar and turbulent boundary layers, respectively