free turbine

free turbine

[¦frē ′tər·bən]
(mechanical engineering)
In a turbine engine, a turbine wheel that drives the output shaft and is not connected to the shaft driving the compressor.

free turbine

free turbineclick for a larger image
Free turbine in a turboprop engine.
A separate turbine that is not mechanically connected to the remainder of the engine, as for example in some turboprop engines that drive the propeller. Arrangements have to be made for braking the propeller, to prevent it from spinning in a wind when the aircraft is at rest, and for shutting off the fuel when the power turbine is unloaded. See also free power turbine.
References in periodicals archive ?
Request for quotations : module of a free turbine mst-198 with a shaft module for operation as part of a gas turbine drive of a gas turbine unit gtu55 st-20 complete with spare parts and accessories (the configuration of spare parts according to p.
The sixth disc is a free turbine disc, which consists of an Inconel alloy to withstand the high temperature loads from the postcombustion gases.
By observing Figure 3 and the schematic model of the rotor-bearing system depicted in Figure 4, it is clear that the most critical component of the rotor-bearing system is the single-stage free turbine disc (D6).
The vibration amplitudes were analyzed in both the five-stage axial compressor and the free turbine disc because the tip blade clearances of these components were defined to be as small as possible for maximum fluid dynamic efficiency.
The vibration amplitudes were analyzed at the five-stage axial compressor and the free turbine disc.
The vibration amplitudes reached 5.9 ^m at the five-stage axial compressor region and 8.6 mm at the single-stage free turbine disc for an operating speed range of 22,520 to 28,150 rpm.
The vibration amplitudes reached 6.2 [micro]m at the five-stage axial compressor region and 8.0 [micro]m at the single-stage free turbine disc region for an operating speed range of 22,520 to 28,150 rpm.
As the pilots double-checked the gauges, the free turbine No.
As P&WC saw it, the free turbine design was more complex to manufacture, but required less starting energy, hence it could self-start easily without ground support and it could have simpler fuel controls.
Tenders Are Invited for Procurement of Qty-02 of Part Number:70bm041040 Description: Module-04 Free Turbine for Our Dauphin N Types of Helicopters Document Purchase Start date : 08 Sep 2017 Document Purchase End date : 05 Oct 2017 Opening date : 06 Oct 2017
Like the PT6, the H engines are free turbines, with a gas generator section directing energetic gas toward a power turbine that connects to the prop through a gearbox, but not to the compressor section of the engine.