How Air and other Gases Move - Aerodynamics

Aerodynamics is the study of forces (more pushes and pulls) acting on an object because air or another gas is moving around it. These forces are important for the design of airplanes, sailboats, cars, and other objects moving quickly through the air. Buildings, bridges, and windmills are also affected by the wind moving past them, and they also experience aerodynamic forces.

The bulk of the sections in this chapter are devoted to understanding the motions of air around objects. When these motions are defined and measured, they contribute to the calculation of the forces on the object. With the aerodynamic forces known, the flight possibilities of the object can be discussed!

How High Speed Gases Change - Gas Dynamics

When air flows over an object at very high speeds, like over fighter aircraft or the Concorde, or when it goes through jet engines with very high temperatures, it can change. The rules and laws for aerodynamics don't always work for these situations. Another area of study, gas dynamics, has been developed for these cases. Gas dynamics expands the rules and laws of aerodynamics to include high speed flows and high temperature flows.

Sometimes, if an aircraft flies so high up and so fast, even the rules of gas dynamics break down. At these conditions, the molecules of the atmosphere are very far apart and do not follow the basic rules. Also, the temperatures around the plane can be so high that they cause chemical reactions among the air molecules. This is often called the hypersonic region, and hypersonics is the study of the air motion in these conditions. The new HSCT, High Speed Civil Transport, that the government is trying to build would fly in this region!

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Last modified: Mon Jun 15 20:45:02 PDT 1998

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