Small scale gas turbine jet engine developed indigenously

Most of us would have surely seen supersonic jets cruising in the high skies with speeds greater than the speed of sound. Their terrifying sound and excellent maneuverability have always fascinated us but the question which provoked my curiosity since childhood was that what those covert forces are which enable this magnificent flight. Flying like birds have been a very old dream of mankind which became a reality when we understood the basic forces of nature like lift, drag and pressure. However, man didnt only rely on the invention of airplane but now he wanted to fly faster and faster in the skies. Propeller engines were not powerful enough to make this ambitious dream come true hence efforts begun to develop a new kind of engine. A German physicist Hans von Ohain and an English pilot dreamed of this extraordinary machine for the first time. Steady flying planes simply could not compete the flight of their imaginations. Furthermore, slow speed of ordinary propeller engines, their noise and exhaust annoyed these two inventors too much and provoked them to invent an engine which will be free of these problems and would cruise extremely fast in the skies. Ohain thought of using Newtons third law of motion to realize his dream. According to that, every action has an equal and opposite reaction, as a deflating balloon experiences an opposite force due to the discharge of air. An engine based on a similar principle would be desirable to achieve incredibly high speeds. This engine could be as following:

The air enters from one side of the engine, is compressed and brought to a combustion chamber where combustion takes place. The heat produced by the combustion will explosively push the air outside through a Nozzle and the engine would experience enormous thrust in the opposite direction. Ohain named this machine the Jet engine.

Nobody knew that a machine based on such a simple principle would remain a crucial part of aviation even after 85 years of its invention. A jet engine is heart of todays modern aircraft and enables a quick and elegant flight.

Let us introduce our indigenously designed and made Gas turbine jet engine in Pakistan. The basic principle is still the same as of Ohains or Whittles engine. Out Jet engine consists of four main components. A compressor compresses the incoming air and increases its pressure. This compressed air is mixed with fuel in a stichiometric proportion and the mixture burns explosively. The hot gases discharge through the exhaust nozzle (visible as glowing flame in figure). These fast moving gases produce thrust as well as keep the compressor and turbine in operation.

The self-sustaining speed of this engine is about 20,000 RPM and can achieve over 70,000 revolutions per minute. The air is compressed to a pressure of 21 PSI (pounds per square inch) producing a pressure ratio of 1.4. The exhaust gases reach a temperature of 600°C and a velocity of 267 m/s. The gas turbine engines have mainly two applications, one in transport as it produces thrust and second in power generation. The above described engine can be employed in both cases after small modifications. The smaller version of this engine is capable of producing 7 kg(70 N) of thrust or 8 kW of electrical power. However, the bigger version can achieve 30 kg(300 N) of thrust or 37 kW of electrical power. These micro turbines are ideal for small power generation units especially in remote areas. Their efficiencies can be significantly higher than other thermal engines. Other applications include jet powered vehicles, racing cars, aircrafts and research.-

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