# Aircraft Hydraulics

Topics: Hydraulic machinery, Hydraulics, Fluid dynamics Pages: 17 (3354 words) Published: April 16, 2014
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Q1) Explain the various principles involved with hydraulic fluids (P1) There are 4 types
PASCAL’S LAW
DIFFRENTIAL AREAS
BRAMAH’S PRESS
BERNOULL’S PRINCIPLE

Pascal’s Law
Pascal’s law defines the fundamental principle of power transmission by hydraulic system. The Pascal’s Law is the main principle behind all hydraulic systems. It is stated pressure is an enclosed container is transmitted equally and undiminished to all parts of the container and acts at right angles to enclosed walls. The size, shape and volume is irrelevant. There are two main equation in equations in hydraulic system these are applied in order to calculate the parameters.

(1) Force (N) = [(Area) (m2)] X [(Pressure) (Pa)]

Using the above equation any of the variables can be found
As per this equation lesser the area more the force the force applied

An important relationship in hydraulics is the area of a piston, the distance it moves and the volume of fluid displaced.

In hydraulics mechanical devices are used called actuators, these Actuators consist of an encased movable piston.

(2) Volume = Area X Distance

Using this equation the volume required to move the piston with an area by a Certain distance can be determined or any other variable in mind.

DIFFERENTIAL AREAS

Differential areas this is caused by the area of the piston being reduced on one side by an amount equal to the cross sectional area of the piston rod. The movement of the piston depends on the pressure of the fluid and the area of the position if there is no cavitation.

THE BRAMAH’S PRESS
It is acceptable that fluid pressure acts equally in all directions and that the load, which can be moved by a piston, depends upon the pressure and the piston area. BRAMAH Stated, “Under a given load, the smaller the area its acts upon the greater the pressure produced and “The greater the area under pressure, the greater the force available.”

BERNOULLI’S PRINCIPLE
Bernoulli's principle states when a fluid flows through a pipe of varying diameter, the amount of energy per kilogram of liquid does not change. For example, pressure is lowest when velocity of the flow is greatest; also, flow is slowest through the widest parts and fastest through the thinnest parts of a tube.

Bernoulli’s Principle stated that the total sum of energies in as incompressible fluid flow is constant provided losses are ignored.

Q2. How fluid flow and direction is controlled? (P1)

This enables - alternatively to mechanics, electrics and pneumatics - power transmission, energy transmission or force transmission / torque transmission to occur.

In hydraulics, power transmission is enabled by using hydraulic fluids, general special mineral oil, but increasingly also by eco-friendly fluids, such as water or special ester or glycols.

The transmitter power results from the factors of pressure and fluid flow. By introducing pressurized fluid into cylinders, the pistons and piston rods inside are set into linear motion, which is utilized by work operations and for driving machines.

Rotating actuators also be realized by means of fluid pressure, for instance with hydraulic motor.

Valves control the inlet and outlet of fluids or control and regulate the flow direction. Electromagnetic actuators are suitable for the control of valves; components in the valve are actuated by the armature.

Some type of Valves:

Gate Valves - flow is controlled by means of a wedge or a gate, the movement of which is usually controlled by a handle.

Directional Control Valves - these are designed specifically for the purpose of directing the flow of fluid, as the desired time, to the point in a fluid power system where the fluid is applied to accomplish work.

Check Valves - basically these valves permit flow in one direction only and prevents the flow in the other direction....