In the case of a facility that uses a reaction turbine, the pressure of the water changes as it moves through the turbine. Thus there must either be a pressure or velocity change to make up for this change in gravitational potential energy. The position of the water has clearly changed, dropping to a lower elevation at the turbine compared to the height at which it was held in the reservoir. Although this might seem counter-intuitive, by breaking apart Bernoulli's equation this phenomenon can be explained. Īfter moving through the turbine and transferring energy to it to generate electricity, water exits at the same speed but the water pressure has changed significantly. If the diameter of the tube does change, the Bernoulli effect comes into play and the velocity of the water increases as the diameter of the tube decreases, leading to a decrease in pressure. Water flows through this tube at a given speed, and exits at the same speed, provided that the diameter of the tube does not change. These penstocks are effectively large tubes that have a turbine at the end of them.

In a hydroelectric dam, water from a hydroelectric reservoir moves down into the penstocks. Water that is under pressure also has a type of pressure-related energy, and all three types are related by Bernoulli's equation and used in determining how much energy one can obtain from water in a hydropower station. Moving water has energy in the form of kinetic energy, while water at high elevations has potential energy. It can also be used in other fluid mechanics problems, such as explaining how the shape of a plane wing produces lift and why fire hydrants spray water high in the air when they are tested. This pressurized air is then used to turn a turbine, and Bernoulli's principle can describe the speed and pressure of the air as it flows to the turbine.īernoulli's equation can be applied in a number of different situations, but in terms of energy it finds use in determining the energy available in hydroelectricity generation facilities.

The ability to look at how air flows around turbines is useful in determining how the turbines will operate and how much power can be generated.įinally, Bernoulli's equation is used in Compressed Air Energy Storage or CAES as air is compressed with an air compressor, pressurizing it and pushing it below ground into a storage area.

Although useful in determining these pressures and velocities, it cannot be applied to air passing through the wind turbine itself, rather it can only be used to investigate the air flow on either side. This equation can be used to calculate the hydraulic head difference across a hydroelectric dam as well as the head losses, due to friction, that determine the effective head across a dam.Īdditionally, Bernoulli's equation is useful with respect to wind power as it is used to relate the velocity of the flow of air to the pressure difference across the turbine.

This equation can be expressed as: P + rac The equation used relates the energy of the fluid in terms of its elevation, pressure, and velocity and relies on the principles outlined by the law of conservation of energy. Bernoulli's equation is an approximation and may sometimes include a term to describe the loss of energy from the system. It shows the equivalence of the overall energy for a given volume of a fluid as it moves. Bernoulli's equation expresses conservation of energy for flowing fluids (specifically incompressible fluids), such as water.

Bernoulli principle