Why does pressure drop in a turbine?

Steam turbine is a power developing device. As the high pressure steam is directed on the blades, it’s kinetic energy is converted into the rotation of turbine blades by providing a thrust to them,this leads to drop in pressure and temperature. It’s called expansion of steam.

Does enthalpy change in turbine?

As the flow passes through the turbine, the total pressure (pt) and temperature (Tt) decrease. From the conservation of energy, the turbine work per mass of airflow (TW) is equal to the change in the specific enthalpy of the flow from the entrance to the exit of the turbine.

What is enthalpy drop?

Thus low enthalpy drop means high mass flow and high volumetric flow, which makes the turbine design stage easier (larger relative blade height).

Does pressure decrease across a turbine?

Since the turbine extracts energy from the flow, the pressure drops across the turbine. This pressure gradient helps keep the flow attached to the turbine blades. So the pressure drop across a single turbine stage can be much greater than the pressure increase across a corresponding compressor stage.

Why does the pressure drop slightly or remain constant in the combustion section of a turbine engine?

There is a velocity decrease as air flows from a small inlet to a larger outlet. As velocity decreases, impact pressure (Pi) also decreases. Since no energy is added or subtracted from the system, total pressure (Pt) for the air remains constant and static pressure (Ps) increases.

Does pressure change across a turbine?

There is no pressure change of the fluid or gas in the turbine blades (the moving blades), as in the case of a steam or gas turbine, all the pressure drop takes place in the stationary blades (the nozzles).

Is the ratio of actual enthalpy drop to isentropic enthalpy drop?

Detailed Solution. Explanation: Nozzle: Nozzle is a duct that increases the velocity of the flowing fluid at the expense of pressure drop. It is the ratio of actual enthalpy drop to the isentropic enthalpy drop.

What defined as the ratio of static enthalpy drop in the rotor to the static enthalpy drop in the stage?

In turbomachinery, Degree of reaction or reaction ratio is defined as the ratio of the static pressure drop in the rotor to the static pressure drop in the stage or as the ratio of static enthalpy drop in the rotor to the static enthalpy drop in the stage.

Why there is no pressure drop in impulse turbine?

In Impulse type turbine steam expands in the nozzle firstly. Hence its pressure remains constant on both ends of the moving blades.

Is shaft work done by a jet engine?

In the axial turbine, cascades of small airfoils are mounted on a shaft that turns at a high rate of speed. Since no external heat is being added to or extracted from the turbine during this process, the process is isentropic. Work is done by the flow to turn the turbine and the shaft.