Twin Shaft VGTD

Twin Shaft VGTD additional compressor driven by the free turbine is controlled by maintaining a constant speed of the free turbine, which is taken from the power to drive the alternator. Additional compressor power is typically controlled by changing the angle of the vanes and BHA bypass portion of the compressed air from the compressor to the nozzle. There are no motors and circuits controlled VNA.

The most widely used for the mid- and far-highways aircraft found VGTD single-shaft scheme with adjustable VNA additional compressor bypass valve and compressed air from a controlled depending on the flow of air through the compressor. In his example, let us consider the main characteristics of the control system VGTD.

To manage the startup and acceleration VGTD used management program type:

The first program control start and acceleration is fairly simple to implement. However, a wide range of environmental conditions, it may not accurately withstand the specified start time. This disadvantage is not present at the second of the regulation. In the absence of stringent requirements for the start-up time VGTD widely used simpler third program.

Under certain environmental conditions, for example at an elevated temperature of outside air, the bleed air from the compressor during start-up may be an increase in the gas temperature before the turbine. To protect against exceeding the specified limits using software limit T = const. VGTD special feature is to limit the temperature of the gas by limiting the flow of bleed air exposure to BHA or shutter in the path selection.

Regulation on the engine load conditions in the selection of power is carried out maintaining the physical rotor speed power turbine = const.

BHA management service is provided by the compressor depending on the flow of compressed air to the needs of JIA. During start-up VNA VGTD blades are in the guise of position. The power drawn from the turbocharger, is minimal.

The work of TGTD on idle and electric power take-off modes occurs with a fully shielded VNA. The modes of starting the engine and the heating of the cabin of the aircraft are provided with fully open position of the VNA, and work on the longest modes of air conditioning of the passenger compartment can be carried out at different positions of the VNA set by the airflow control valve in the air-conditioning system of the aircraft. When the capacity of this valve is changed, the VGTD ACS receives a signal about the degree of its opening and, with correction for the outside air temperature, changes the position of the VNA blades. At the same time, within the permissible reserves of the compressor's stable operation, the level of bleed air pressure remains constant.

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