Question

QUESTION 2 (14 marks) Explain how to form a steady uniform flow around a cylinder based on superposition (6 marks) (a) of several basic potential flows. (b) Based on the surface pressure distribution of the flow around the cylinder in (a) explain why the theoretical pressure distribution as illustrated in Fig. 1 is different (8 marks) from the corresponding experimental results. 3 Experimental Theoretical (inviscid) -3 0 30 60 90 120 150 180 β (deg) Figure 1

Answer 1

a) Superimposition of Rectilinear and Doublet gives the required flow around a Cylinder.

The following solution gives complete idea:

2 21 2y b W.K.T This ase s Krown as om TI

Saato Peint at seld

au 下下 P- Po P- Po ul 2- T-T 24
b)

In the earlier case we assumed the flow to be ideal. But for a real flow, the following effects are come into picture:

1. Fluid near to solid surface loses it's KE because of Friction.

2. When Adverse Pressure Gradient occurs the opposite force acts on fluid which causes them to flow in opposite direction and hence Reversal Flow Occurs which is known as Boundary Layer Seperation.

The decrease in KE increases the Value of Y-axis parameter in above graph and hence the Experimental Graph is above the Theoretical Graph.

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