david b.
Posts: 2894
Joined: Fri Jun 15, 2001 7:18 pm

Sand Effects On Engines

Wed Mar 26, 2003 6:13 am

War-tech related question. How well does a turbine stand up to sand ingestion? Turbojets and turboshafts mainly.

Can a plane like a F-15 or a helo fly during today's brutal sandstorm or do they have to be grounded?

Teenage-know-it-alls should be shot on sight
Posts: 1299
Joined: Wed Apr 24, 2002 8:04 pm

RE: Sand Effects On Engines

Wed Mar 26, 2003 6:44 am

Sand can have a couple of effects on a turbine engine.

First, the sand can abrade the compressor blades resulting in reduced engine power and eventually compressor stalls due to reduce stall margin or, in extreme cases, blade failure due to the blades being abraded down to very thin airfoils.

The other problem is sand getting into the passages from the compressor that supply cooling air to the turbine vanes and blades. These passages are very small and can be plugged up or the sand can make its way into the blade and vane cooling passages, melt, and cause blade or vane failure due to contamination of the metals or coatings.

Vanes are airfoils that are fixed and blades are airfoils that rotate.

In modern turbine engines, inlet temperatures to the first stage turbine nozzle guide vanes can reach 2500 degrees F at high engine power.
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

RE: Sand Effects On Engines

Wed Mar 26, 2003 5:05 pm

Some engines are designed for such conditions though. The CT7 engines of the Apache are, for instance. They have a separator built into the inlet which picks out sand and other FOD from the intake air. On the CT7 equipped aircraft I worked with, the bypass duct sent it all into the oil cooler instead (if the prop and the engine didn’t get that sparrow, the oil cooler would!), but that’s a different story. The fact that the rotor blades of the Apaches can’t take the sand anyway is another different story...

I thought I was doing good trying to avoid those airport hotels... and look at me now.
Posts: 141
Joined: Fri Dec 22, 2000 1:51 pm

RE: Sand Effects On Engines

Thu Mar 27, 2003 2:44 am

On the Chinook, there is a centrifugal separator on the inlet that 'spins out' any small objects entering the inlet, these are then dumped over-board.

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