Question
Download Solution PDFWhen Mach number is less than unity, the flow is called-
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Mach number
Mach number is defined as the ratio of inertia force to elastic force.
\(M = \sqrt {\frac{{Inertia\;force}}{{Elastic\;force}}} = \sqrt {\frac{{\rho A{V^2}}}{{KA}}} = \sqrt {\frac{{{V^2}}}{{\frac{K}{\rho }}}} = \frac{V}{{\sqrt {\frac{K}{\rho }} }} = \frac{V}{C}\;\;\;\;\left\{ {\sqrt {\frac{K}{\rho }} = C = Velocity\;of\;sound} \right\}\)
\(M = \frac{{Velocity\;of\;body\;moving\;in\;fluid}}{{velocity\;of\;sound\;in\;fluid}}\)
For the compressible fluid flow, Mach number is an important dimensionless parameter. On the basis of the Mach number, the flow is defined.
|
Mach Number |
Type of flow |
|
M < 0.8 |
Sub-sonic flow |
|
0.8 < M <1.3 |
Trans-sonic |
|
M = 1 |
Sonic flow |
|
1.3 < M < 5 |
Super-sonic flow |
|
M > 5 |
Hypersonic flow |
Other important dimensionless numbers are described in the table below
|
Reynold’s number |
\(R_e=\frac{{{inertia force}}}{{{viscous force}}} = \frac{{{\bf{\rho VL}}\;}}{{\bf{\mu }}}\) |
|
Froude Number |
\({F_r} = \sqrt {\frac{{inertia\;force}}{{gravitation\;force}}} = \frac{V}{{\sqrt {{\bf{Lg}}} }}\) |
|
Euler number |
\({E_u} = \sqrt {\frac{{inertia\;force}}{{pressure\;force}}} = \frac{V}{{\sqrt {P/\rho } }}\) |
|
Weber Number |
\({W_e} = \sqrt {\frac{{inertia\;force}}{{surface\;tension}}} = \frac{V}{{\sqrt {\sigma /\rho L} }}\) |
Last updated on Jun 16, 2025
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