Fundamentals of Gas Dynamics

Gas dynamics is the field of study associated with the forces and motion of gasses. It is a subset of the general field of fluid dynamics that considers liquids in addition to gasses. Many fluids can be considered incompressible. This provides a degree of simplification to the equations that govern the motion of the fluid. A gas is compressible and the coupling between the fluid properties such as density, pressure, and temperature creates a close link between gas dynamics and thermodynamics. Choked flow and shock waves are two phenomena that are encountered with gases that are not generally encountered with liquids. These phenomena are directly related to compressibility effects.

Year Published: 
2014

Learning Objectives

Learn the fundamental concepts, terminology, and equations used in one-dimensional gas dynamics.

Software Covered: 

Properties

Properties

Specific heat and entropy are two properties that are particularly important in the study of Gas Dynamics.

Mach Number

Mach Number

The Mach number is one of the primary parameters used to characterize flow in the field of Gas Dynamics.

Stagnation State

Stagnation State

The stagnation state is a reference state that exists if the fluid is brought to zero velocity and zero potential (i.e. z=0).

Mach Number Equations

Mach Number Equations

The equations that relate the static and stagnation properties of an ideal gas can be written in terms of the Mach number.

Pressure-Energy Equation

Pressure-Energy Equation

A useful form of the energy equation can be developed that does not include a heat transfer term.

Varying Area Flow

Varying Area Flow

One of the most common and important types of internal flows is one in which the cross sectional area of the pipe or duct changes.

Nozzles and Diffusers

Nozzles and Diffusers

Nozzles and diffusers are devices that can be analyzed using the area ratio equations. Nozzles are defined as devices that convert enthalpy into kinetic energy.

Authors

Robert
LeMaster
PhD., PE
University of Tennessee Martin