Coefficient of contraction

Denoting the ratio of the area at section C to that at section 2 by a coefficient of contraction Cr ... 

The area of flow decreases from A at section 1 to Ao at the orifice and then to A2 at the vena contracta (Figure 6.14). The area at the vena contracta can be conveniently related to the area of the orifice by the coefficient of contraction Cc, defined by the relation ... 

Calculate the pressure drop in, and the power required to operate, a condenser consisting of 400 tubes 4.5 m long and 10 mm internal diameter. The coefficient of contraction at the entrance of the nibes is 0.6. and 0.04 mJ/s of water is to be pumped through the condenser. 

Coefficient of contraction Cc. The ratio of the area of a jet A at the vena contracta to the area of the orifice or other opening A0 is called the coefficient of contraction. Thus, A = CcAa. 

The coefficient of contraction may be obtained by measuring the diameter of the jet with suitable calipers, which must be rigidly supported. Precision may be lacking, especially in the case of small jets. 

The coefficient of contraction, frictional losses between the tapping points, and kinetic energy corrections are absorbed in the coefficient of discharge. The volumetric flow rate is then given by Eq. (7). 

To determine the discharge of the flow, the discharge coefficient (Q) is defined as the ratio of the actual volume discharged from the orifice in a given time to the theoretical discharge. Similarly, the coefficient of contraction (Cc) is the ratio of the actual area of the jet at the vena contracta to the area of orifice. The relationship between the coefficients is as follows ... 

Where different materials use gradedly laminated together, the coefficient of contraction. Therefore, the FGM may bend after baking. It is now examined how far this bending can be relaxed, by varying the layer steps and the thickness of the FGM. 

Matching the sealant s coefficient of contraction, within the temperature range, with that of the substrate. 

The coefficient of discharge is a composite of several components that affect the flow. Two of these components are the coefficients of contraction and velocity. In this work no attempt was made to evaluate the components separately. According to Prandtl [ ] the coefficient of velocity differs considerably from unity for small orifices and low velocities w hen the ratio of the orifice diameter to the pipe diameter is small. For large openings and high velocities it is usually close to unity. 

For a thin plate or sharp-edged orifice, the vena contracta is assumed to he one half of an orifice diameter downstream from the orifice, hut in reality the distance may he from 30% to 80% of di-For flow of water at a high Reynolds number through a small orifice diameter, Lindeburg (1998) reported that the contracted area is approximately 61% to 63%. The coefficient of contraction is defined as... 

---