Relevant Theory\ Boundary layers can exist in two forms: a) Laminar & b) Turbulent. In the case of the floor of the wind tunnel, the boundary layer will definitely be turbulent in nature.\ For the growth of a turbulent boundary layer the recognised standard expression for boundary layer thickness (see MIET 2354: Thermo-Fluid Mechanics 3 notes) is expressed as:\

\\\\delta =0.371\\\\times (Re_(x))^(-(1)/(5))

\ If the velocity profile can be expressed as:\

(u)/(U)=((y)/(\\\\delta ))^((1)/(7)),

and

\\\\delta \\\ ho \\\\mu \\\\delta _(1)=0.371x_(1)(Re_(x_(1)))^(-(1)/(5)) and \\\\delta _(2)=0.371x_(2)(Re_(x_(2)))^(-(1)/(5))\\\\delta _(1)=0.371x_(1)((\\\ ho Ux_(1))/(\\\\mu ))^(-(1)/(5)) and \\\\delta _(2)=0.371x_(2)((\\\ ho Ux_(2))/(\\\\mu ))^(-(1)/(5))Ux_(1)x_(2)\\\\delta _(1)\\\\delta _(2)(x_(1)-x_(2))30\\\\deg rmmP_(a)-P=((r-r_(a)))/(10^(3))sin30\\\\deg \\\ ho _(m)gPa\\\ ho _(m)782k(g)/(m^(3))5\\\\times 10^(5)\ And if the boundary layer thickness \\\\delta is estimated at two different distances from the assumed start of the boundary layer (unknown in this case), then \\\ ho and \\\\mu can be found from ambient temperature and the appropriate table of fluid properties for air.\ \\\\delta _(1)=0.371x_(1)(Re_(x_(1)))^(-(1)/(5)) and \\\\delta _(2)=0.371x_(2)(Re_(x_(2)))^(-(1)/(5))\ Or\ \\\\delta _(1)=0.371x_(1)((\\\ ho Ux_(1))/(\\\\mu ))^(-(1)/(5)) and \\\\delta _(2)=0.371x_(2)((\\\ ho Ux_(2))/(\\\\mu ))^(-(1)/(5))\ U can be determined from the Pitot static tube on the top of the experimental rake. Thus, an estimate can be made of x_(1) and x_(2) if \\\\delta _(1) and \\\\delta _(2) can be measured. Hence it will be possible to estimate (x_(1)-x_(2)) and this can be compared with the distance between the two positions chosen in the wind tunnel.\ Also the two Reynolds numbers can be estimated and it is possible to identify the nominal start position of the boundary layer.\ Note on the Manometer:\ The 36-tube sloping tube Manometer is not pre calibrated. If the Manometer is set for example at 30\\\\deg then each active tube can be measured relative to one left open to the atmosphere. If the reading along the tubes is rmm :\ P_(a)-P=((r-r_(a)))/(10^(3))sin30\\\\deg \\\ ho _(m)g\ Pa\ m\ Here, \\\ ho _(m) is the density of the Manometer fluid and is equal to 782k(g)/(m^(3))\ 10

6. Relevant Theory Boundary layers can exist in two forms: a) Laminar \& b) Turbulent. In the case of the floor of the wind tunnel, the boundary layer will definitely be turbulent in nature. For the growth of a turbulent boundary layer the recognised standard expression for boundary layer thickness (see MIET 2354: Thermo-Fluid Mechanics 3 notes) is expressed as: =0.371(Rex)51 If the velocity profile can be expressed as: Uu=(y)71and5105