Graham Warwick/WASHINGTON DC
A new gas turbine fuel control technology offering potential weight, cost and power savings has been tested successfully on an AlliedSignal TFE731-5 turbofan. The system combines a Lucas Aerospace fuel control unit with a split discharge pump produced by US company Vickers.
In conditions when fuel consumption is low, a conventional pump system pressurises more fuel than is required by the engine. Excess pressurised fuel is recirculated through the pump, causing its temperature to rise.
Lucas says that its new control unit recognises the low usage condition and causes the split discharge pump to divert excess fuel back to the pump inlet at low pressure, reducing the temperature rise by as much as 60%. Reducing the temperature rise "enables the use of smaller fuel/oil heat exchangers and reduces or eliminates the need for air/oil heat exchangers, resulting in weight, cost and power savings", says Lucas.
More significantly, the reduction is achieved without impairing engine responsiveness. "The system introduces very little response lag," says the company.
The unit tested by AlliedSignal was configured so that 70% of the pump flow was unpressurised at low fuel consumption conditions.
Lucas says that the new fuel control system is applicable to any gas turbine, and can be configured with any split ratio to optimise heat management and engine performance. Further testing is planned while Lucas and Vickers continue market studies.
Source: Flight International
