Drag coefficient flat plate

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. 

FIG. 14-113 Drag coefficient for flow past inclined flat plates for use in Eq. (14-228). Calveii, Yung, and Leung, NTIS Puhl. PB-24S050 based on Page and Johansen, Proc. R. See. (London), H6A, 170 (1927).]... 

Momentum boundary layer calculations are useful to estimate the skin friction on a number of objects, such as on a ship hull, airplane fuselage and wings, a water surface, and a terrestrial surface. Once we know the boundary layer thickness, occurring where the velocity is 99% of the free-stream velocity, skin friction coefficient and the skin friction drag on the solid surface can be calculated. Estimate the laminar boundary layer thickness of a 1-m-long, thin flat plate moving through a calm atmosphere at 20 m/s. 

Equation (5-56), called the Reynolds-Colburn analogy, expresses the relation between fluid friction and heat transfer for laminar flow on a flat plate. The heat-transfer coefficient thus could be determined by making measurements of the frictional drag on a plate under conditions in which no heat transfer is involved. 

Glycerin at 30°C flows past a 30-cm-square flat plate at a velocity of 1.5 m/s. The drag force is measured as 8.9 N (both sides of the plate). Calculate the heat-transfer coefficient for such a flow system. 

G. Laminar and turbulent, flat plate, forced flow >=7h = = 0.037 Chilton-Colbum analogies, Nsc = 1-0, (gases), /= drag coefficient. Corresponds to item 5-21-F and refers to same conditions. 8000 < < 300,000. Can apply analogy,=/ 2, to entire plate (including laminar portion) if average values are used. [100] p. 193 [109] p. 112 [146] p. 201 [151] p.271... 

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). 

SOLUTION A flat plate is subjected to air flov/, and the drag force acting on it is measured. The average convection coefficient is to be determined. Assumptions I Steady operating conditions exist. 2 The edge effects are negligible. 3 The local atmospheric pressure is 1 atm. 

For flat plates, the drag force is equivalent to friction force. The average friction coefficient Qcan be determined from Eq. 6-11,... 

C What does the friction coefficient represent in flow over a flat plate How is it related to the drag force acting on the plate ... 

B Develop an intuitive understanding of friction drag and pressure drag, and evaluate the average drag and convection coefficients in external flow, a Evaluate the drag and heat transfer associated with flow over a flat plate for both laminar and turbulent flow,... 

For parallel flow over a flat plate, the pressure drag is zero, and thus the drag coefficient is equal to the friction coefficient and the drag force is equal to the friction force. 

As shown in Fig. 5, most PCP capsules have two plates attached to the two flat ends of each capsule, called seal plates, or two rings around the capsule body near the two ends, called seal rings. Their purposes are the same to seal the ends of the capsule so that little air passes through the seal and around the capsule. This generates a large drag coefficient... 

These equations have formed the basis of most theoretical investigations on the determination of the average fluid velocity and the drag coefficient in the stabilized region of turbulent flow on a flat plate. In what follows, major attention will be paid to empirical and semiempirical formulas that approximate numerous experimental data quite well. 

The formula for the viscosity coefficient of a gas can be derived in a way similar to that used f or heat conduction. We imagine two very large parallel flat plates, one lying in the xy-plane, the other at a distance Z above the xy-plane. We keep the lower plate stationary and pull the upper plate in the + x direction with a velocity U. The viscosity of the gas exerts a drag on the moving plate. To keep the plate in uniform motion, a force must be applied to balance the viscous drag. Looking at the situation in another way, if the upper plate moves with a velocity U, the viscous force will tend to set the lower plate in motion. A f orce must be applied to the lower plate to keep it in place. 

In Sec. 6.13 we showed that the drag force on numerous bodies could be represented in terms of plot of drag coefficient versus Reynolds number. If we now define a local drag coefficient for some small part of a flat plate as... 

Local drag coefficient for a flat plate. Experimental data are compared with Blasius solution (Eq, 11.16) and with Prandtl s equation (Eq. 11.36). [From H. W. Liepmann and S. Dahwan, Direct measurements of local skin friction in low-speed and high-speed flow, Proc. First U.S. Natl. Congr. AppL Mech, ASME, New York, 1952, p. 873. Reproduced with the permission of the publisher,] I... 

Consider a flat plate such as a single blade on an agitator, with a fluid passing about it at a relative velocity, v. The dynamic pressure exerted on the plate is theoretically and the theoretical force F is this pressure multiplied by the plate area, i.e. f, = pv A. The actual force on the plate F is related to the theoretical force by a drag coefficient Co where Co = FJF thus ... 

They offered expressions for the drag coefficient versus the gas Reynolds number for each of the three aspect ratios (see chapter 5 for details). For e < 0.25, the ellipse becomes thin and close to a plate shape and one can assume a value of Cd 2, which is a reasonable value for a flat plate over a wide range of Reynolds numbers. So, as the element is being deformed by the aerodynamic force in our model, its instantaneous Reynolds number (based on its semi-major axis) and the corresponding drag coefficient can be calculated by interpolating between the expressions offered for drag by Mashayek et al. [6]. As shown by their study. 

Obtain expressions for the local and mean values of the wall shear stress and friction factor (or drag coefficient) for the laminar boundary layer flow of an incompressible power-law fluid over a flat plate Compare these results with the predictions presented in Table 7.1 for different values of the power-law index. 

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. 

Assuming that a car is equivalent to a flat plate 1.5 m square, moving normal to the airstream, and with a drag coefficient, Co = 1 1/ calculate the power required for steady motion... 

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