Don't worry, let's go back to the opening day of Hsinchu Camp District on November 21, 2006. Presumably, many friends through the news screen know that IDF was in the event of acrobatic flight, and there was a suspected bird strike that caused the engine to stall. And after falling behind the front fuselage, there was a lot of black smoke, which scared many people.
Let's talk about this protagonist from this thick black smoke: "IPS Integrated Power System"
According to the Jane Yearbook's brief description:
ITEC Integrated Power System (IPS) is used by the Honeywell C36-120 Auxiliary Power Unit (APU) for ground system inspection and start-up engines. If the twin engine fails during flight, the emergency power unit (EPU) is automatically activated by the high-pressure mixed gas, and the APU is started by the shared gear box (Gear Box, GB). The APU operates at temperatures below 7,620 m (25,000 ft) and the EPU is below 16,460 m (54,000 ft).
Looking back at the situation of IPS development, as described by General Huaxi Xi’s " The Story of Yunhan":
Ying Yang decided to use a digitally controlled flight control system, so that the aircraft can be designed to be in an unstable state, reducing drag in the transonic region, and Improve the handling of the aircraft. The only downside is that the power and hydraulics on the aircraft are not allowed to be interrupted.
For twin-engine aircraft, power and hydraulic system interruptions may occur when both engines fail simultaneously and certain power systems or hydraulic systems fail, and according to expert advice, an emergency power system similar to the F-16 should be installed ( Emergency Power System, EPS). In addition, the Air Force requires the aircraft to be equipped with an auxiliary power system, similar to the F-16's Jet Fuel Starter (JFS), to prevent the aircraft from relying on the ground power system for engine start.
GD's recommendation is to combine these two requirements into one system to save space and weight. F-16's EPS uses hydrazine to generate power, and hydrazine is a toxic gas. Under the trend of high environmental awareness, GD has considered switching to a more advanced technology, that is, using high-pressure air to burn fuel to generate power.
At that time, the tool was developed in the AIRESEARCH test room of Garrett's relationship company. It should be combined with Garrett's specialty product APU to develop a new product and integrate the power system (Integrated Power System, IPS).
(The picture is quoted from the story of Yunhan)
The IPS consists of an auxiliary power unit APU, an emergency power unit EPU, and a shared accessory gearbox. An emergency generator and an emergency hydraulic pump are connected to the accessory gearbox.
When the dual-engine failure causes the generator and hydraulic pressure output to be abnormal, the IPS will automatically start to provide emergency power. The EPU will let the accessory gearbox reach the working speed within a few seconds, and will take over the brake after the APU starts. Therefore, no matter whether the EPU or APU is started, it can provide emergency hydraulic power and power supply for IDF to safely return to the field.
The EPU has a dedicated high-pressure air and fuel storage area. It uses high-pressure air and fuel to be forced to burn to drive the accessory gearbox. It can provide IDF at altitudes below 54,000 , for about 2 minutes. However, forced combustion of high-pressure air and fuel will produce a large amount of black smoke, which will really shock the unsuspecting.
When the IDF height is lower than 35,000 ,, the APU starts to actuate, using the fuel of the aircraft itself and the external air intake, and the mixed fuel is burned in the combustion chamber through the first-stage centrifugal compressor, and the EPU actuates the accessory gear box to generate emergency power. At less than 25,000 feet, the APU is still available to power the engine.
(36-150 type APU profile)
In addition, when the APU is operating on the ground, it can also provide a gas source starting engine, so that the IDF can achieve the self-starting operational demand without the need for ground-assisted equipment. Therefore, the IDF retains the Air Force's shortest warning time.
The APU model is 36-120, which is Honeywell's APU designed for IDF, from the 36 series family. Its family member 36-150 series has been used for AH-64, UH-60 and CH-47. In addition, Honeywell's APU has been widely used in military and civil aircraft all over the world. It is a very mature and reliable product. Even the US military's new fighters F-22 and F-35 use Honeywell's APU.
Finally, let us look at the structure of the APU. The left side of the figure shows the accessory gearbox, the middle is the air inlet, the right side is the compressor, the combustion chamber and the turbine. Besides the inability to generate the thrust required by the aircraft, its mode of operation is not with the engine. The same?