Coefficient lifting

The drag force is exerted in a direction parallel to the fluid velocity. Equation (6-227) defines the drag coefficient. For some sohd bodies, such as aerofoils, a hft force component perpendicular to the liquid velocity is also exerted. For free-falling particles, hft forces are generally not important. However, even spherical particles experience lift forces in shear flows near solid surfaces. 

The original work by NACA and NASA is the basis on which most modern axial-flow compressors are designed. Under NACA, a large number of blade profiles were tested. The test data on these blade profiles is published. The cascade data conducted by NACA is the most extensive work of its kind. In most commercial axial-flow compressors NACA 65 series blades are used. These blades are usually specified by notation similar to the following 65-(18) 10. This notation means that the blade has a lift coefficient of 1.8, a profile shape 65, and a thickness/chord ratio of 10%. The lift coefficient can be directly related to the blade camber angle by the following relationship for 65 series blades ... 

L = lift force D = drag force Cl = lift coefficient Cd = drag coefficient A = surface area p = fluid density V = fluid velocity... 

Two coefficients have been defined. Cl and Co, relating velocity, density, area, and lift or drag forces. These coefficients can be calculated from wind-tunnel tests and plotted as shown in Figure 7-6b versus the angle of attack... 

Labyrinth piston, 49 Labyrinth seal leakage, 532 Lantern ring, 74 Lapping block set, 335 Lateral critical speeds, 384 Leakage, seal, 532, 533, 534 Leland-Mueller rule, 26 Lift coefficient, 226 Liquid... 

Figure 14. Capacity correction factors due to overpressure for relief and safety relief valves in liquid service. The curve shows that up to and including 25 percent overpressure, capacity if affected by the change in lift, the change in oriflce discharge coefficient and the change in overpressure. Above 25 percent, the valve is at fidl lift and capacity is affected only by overpressure.

The first terms in (99) and (100) say that adsorption can take place either on the remaining sites of the reconstructed surface or on those surface sites that are neither reconstructed nor occupied. The first term in (101) allows for reconstruction from the unreconstructed area, 1 — 9, but also says that this reconstruction may be hindered or helped if there is an adsorbate on the unreconstructed surface. A similar interpretation holds for the last term in (101) describing the lifting of the reconstruction. For the adsorption coefficients Wy, Ws, etc., one writes expressions analogous to (47). 

The aerodynamic force varies approximately as the square of the flow velocity. This fact was established in the seventeenth centui y—experimentally by Edme Marione in France and Christiaan ITuygens in Holland, and theoretically by Issac Newton. Taking advantage of this fact, dimensionless lift and drag coefficients, and Cj, respectively, are defined as... 

At flow speeds well below the speed of sound, the lift coefficient depends only on the shape and orientation (angle of attack) of the body ... 

The calculation of heat transfer film coefficients in an air-lift bioreactor is more complex, as small reactors may operate under laminar flow conditions whereas large-scale vessels operate under turbulent flow conditions. It has been found that under laminar flow conditions, the fermentation broths show non-Newtonian behaviour, so the heat transfer coefficient can be evaluated with a modified form of the equation known as the Graetz-Leveque equation 9... 

Drag and lift coefficients for rotating spheres. All data plotted are for smooth spheres. 

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