Chapter 3, Problem 3.8P

Interpretation Introduction

Interpretation:

The type of flow for air in the given steel pipe is to be determined.

Concept Introduction:

The formula for the Reynold number, $N_{\mathrm{Re}}$ is defined as:

  $N_{\mathrm{Re}}=\frac{D\overline{V}\rho }{\mu }$ ...... (1)

Here, $\overline{V}$ is the average liquid velocity, $\rho$ is the density of the fluid, $\mu$ is the viscosity of the fluid, and $D$ is the pipe diameter.

The flow is laminar for $N_{\mathrm{Re}}<2100$ and turbulent for $N_{\mathrm{Re}}>4000$ . In between 2100 and 4000, the flow is in transition from laminar to turbulent.

The ideal gas equation is:

  $p=\frac{\rho RT}{M}$ ...... (2)

Here, $\rho$ is the density of the gas, $p$ is the pressure of the gas, $M$ is the molar mass of the gas, $T$ is the temperature of the gas, and $R$ is the universal gas constant.

An ideal gas is the gas which obeys ideal gas laws which is a simplified equation of states.

A real gas behaves as an ideal gas at higher temperature and lower pressure. At STP, a mole of an ideal gas has a volume of $22.4\text{ L}$ .