Flat plate total drag

AP is the pressure drop, cm of water Pg is the gas density, g/cm Ap is the total projected area of an entire row of baffles in the direction of inlet gas flow, cm" and At is the duct cross-sectional area, cm". The value jd is a drag coefficient for gas flow past inclined flat plates taken from Fig. 14-113, while L/ is the actual gas velocity, cm/s, which is related to the superficial gas velocity by U = L/g/cos 0. It must be noted that the angle of incidence 0 for the second and successive rows of baffles is twice the angle of incidence for the first row. Most of Calverts work was with 30° baffles, but the method correlates well with other data on 45° bafiles. 

A flat plate of length L is heated to a uniform surface temperature and dragged through water which is at a temperature of 10°C at a velocity, V. Plot the variation of power required to pull the plate through die water and of the total heat transfer rate from the plate with plate surface temperature for surface temperatures between 10 and 95°C. Comment on the results obtained. The boundary layer on the plate can be assumed to remain laminar. 

A 2-m X 3-m flat plate is suspended in a room, and is subjected to air flow parallel to its surfaces along its 3-m-long side. The free stream temperature and velocity of air are 20°C and 7 m/s. The total drag force acting on the plate is measured to be 0.86 N. Determine the average convection heal transfer coefficient for the plate (Fig. 5-36). 

Engine oil at 60°C flows over the upper surface of a 5-m long flat plate whose temperature is 20°C with a velocity of 2 m/s (Fig. 7-12). Determine the total drag force and the rate of heat transfer per unit width of the entire plate. 

Engine oil at 80°C flows over a 10-m-long flat plate who.se temperature is 30 C with a velocity of 2.5 m/s. Determine Ihe total drag force and the rate of heal iransfer over Ihe entire plate per unit width. 

Reynolds Analogy for Heat and Mass Transfer. For a flat plate, tota 1 frictional drag = b T (x)dx v re b = width of the plate, = length of the plate, and the total heat transferred Q b q(x)dx. 

A polymer solution (density 1022 kg/m ) flows over the surface of a flat plate at a free stream velocity of 2.25 m/s. Estimate the laminar boundary layer thickness and surface shear stress at a point 300 mm downstream from tlie leading edge of the plate. Determine the total drag force on the plate from the leading edge to this point. What is the effect of doubling the free stream velocity ... 

Equation (7.3-13) has been shown to be quite useful in correlating momentum, heat, and mass transfer data. It permits the prediction of an unknown transfer coefficient when one of the other coefficients is known. In momentum transfer the friction factor is obtained for the total drag or friction loss, which includes form drag or momentum losses due to blunt objects and also skin friction. For flow past a flat plate or in a pipe where no form drag is present, //2 = J = Jp- When form drag is present, such as in flow in packed beds or past other blunt objects,772 is greater thanJ, otJ andJ s Jg. 

In Fig. 3.1-la the flow of fluid is parallel to the smooth surface of the flat, solid plate, and the force F in newtons on an element of area dA m of the plate is the wall shear stress T times the area dA or x dA. The total force is the sum of the integrals of these quantities evaluated over the entire area of the plate. Here the transfer of momentum to the surface results in a tangential stress or skin drag on the surface. 

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