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Solar T62T-32 "Titan" Auxiliary Power Unit
The Solar T62 family of engines is a newer, more advanced version of the Solar T41. There are many different variants of the T62, but for the most part they are generally used as aircraft APU's and ground power units, usually turning a generator and some other device such as an external load compressor and/or a hydraulic pump.
The Solar T62T-32, as seen on this website, is one half of a twin engine turbogenerator set whose exact purpose is not specified in the operations and maintenance manual; though its electrical power output could be used in any number of applications. The T62T-32 shown on this website is a single engine, fixed shaft turboshaft engine with a power output of 160 shaft horsepower at an output speed of 6,000 rpm. The electrical generator is not included in this case.
The Solar T62T-32 turboshaft is a compact single shaft turboshaft with an integrated output reduction and accessory gearbox. It is very similar to the Solar T41 in general layout although the performance is much improved. Air is drawn in through the screened radial engine inlet, between the gas turbine assembly and the gearbox housing. Air passes through the inlet housing before being drawn into the single stage centrifugal compressor. The centrifugal compressor pressurizes the air and feeds it through the diffuser and into an annular reverse flow combustor with six fuel injectors. The combustor is the main difference between the T41 and the T62. In the combustor, fuel is mixed with the air and ignited to drive the radial inflow turbine. The compressor and turbine rotors are back to back assemblies; essentially one single integrated rotor with a compressor on one face and a turbine on the other face. The engine exhaust is expelled through an axial flow exhaust diffuser.
At the front of the engine, the rotating shaft turns a planetary gearset which drives subsequent gears in the reduction and accessory gearbox. The geartrain sits in a cast aluminum housing to which the engine accessories and output load are attached. The gearbox housing forms an integral wet oil sump, in which an engine driven oil pump resides. The engine output is driven at 6,000 rpm, while the accessory pads turn at various speeds. Accessories include the aforemention oil pump, a fuel pump and mechanical fuel control/acceleration limiter, and a 24V starter assembly. Engine governing is completely electronic. An external electronic control unit takes an engine speed reading from a gearbox mounted magnetic pickup, and sends a signal to an engine mounted elecrtic torque motor, which moves the fuel lever on the fuel controller to maintain a set rpm. The mechanical fuel control features an acceleration limiter bellows assembly, which uses a compressed air signal bled off the compressor to control the amount of fuel going to the burner during starting, acceleration, and deceleration.
Starting the engine requires energizing the starter and ignition exciter. At 4%, the start fuel valve should open, which sends a small volume of fuel into the burner through a separate pilot fuel nozzle. The fuel ignites upon contact with the igniter as the engine continues to accelerate. At 10%, the main fuel solenoid should be energized allowing main fuel to the burner, which ignites when it comes in contact with the pilot flame. As the engine continues to accelerate, air pressure in the acceleration limiter should build, allowing more and more fuel to be fed to the burner, allowing for smooth acceleration without overtemp, despite the fact that the electric torque motor has the fuel valve fully open to achieve governed speed. At 78%, the starter and igniter are deenergized. At 96% rpm, the three way start fuel solenoid is de-energized, which re-routes additional fuel to the fuel control to assure that there is sufficient fuel flow for full load operation. At 100%, the governor should signal the torque motor to reduce fuel flow to maintain governed speed. It is possible to throttle the engine by changing the governor setting, but the T62 is intended to be a constant speed engine which operates at 100% speed at all times.
Solar T62T-32 Gas Turbine Engine
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