Where does the rotation of gears in an internal gear pump take place in?

Among positive displacement pumps are internal gear pumps, which work through a gear-within-a-gear mechanism where gears rotate within larger fixed outer gears. Another design is external gear pumps, which make use of meshed external gears. In an internal gear pump the inner and outer gears are designed such that teeth of the inner rotating gear (also called rotor) protrude into spaces of the outer stationary gear (known as idler or annulus), but not touching each other.

The following is how rotation in an internal gear pump enables fluid transfer:

1. Rotor-Idler interaction: An internal gear pump comprises a rotating gear or rotor nested inside a non-rotating exterior or idler and its position in casing of the pump.
2. Intake: When the rotor turns, there is creation of expanding volume at one side because they come apart from those on the idler; vacuum thus created draws fluid into the pump casing.
3. Transport of Fluids: The fluid moves through this space between walls that separate teeth on both rotors and idlers while another wall keeps it moving rightwards. As the rotor continues to rotate, the fluid gets trapped between gears’ teeth and casing’s walls thereby shifting it towards discharge end of pump.
4. Discharge: With time, however, these two pairs reconnect as teeth do mesh during rotation’s period on discharging section and he fluid will be discharged via outlet port from this device; therefore pressure forces liquid outside when these teeth join together after meshing again.
5. Continuous operation: The flow rate remains constant since as long as there is rotation of this particular toothed wheel inwards by drawing liquid around it before being pushed outwards for instance; smoothness without pulsations helps in many industrial hydraulic systems for a consistent flow rate of fluids needed

When it comes to processes such as the following:

• Chemical and Polymer Delivery: The internal gear pumps are used to transport chemicals and polymers because they handle viscous fluids well and ensure that flow is maintained.
• Oil and Fuel Transfer: This smooth flow, coupled with the ability to operate under high pressure makes these devices suitable for movement of fuels including lubrication oils in fuel management systems.
• Bitumen and Asphalt Pumping: Quality pumps should be able to pump bitumen and asphalt, which are highly viscous substances, effectively.
• Hydraulic Systems: It is used in hydraulic systems where machinery needs a lot of pressure or hydraulic cylinders/motors have to be moved.
• Food Industry: Syrups, chocolate, and other thick food products can be handled by the internal gear pumps made for use in food industry.

Rotation within the fixed gear ring of an internal gear pump thus becomes a critical mechanism that allows transportation and accurate metering of fluids in various industrial settings involving hydraulics.