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D-S duct: Future of Aviation – Hritik Singh

Article by Mr. Hritik Singh

Full Title: Divertless–Serpentile Duct : The Future of Aviation

“Simplicity is about subtracting the obvious and adding the meaningful” – John Maeda. In fact all the revolutionary technology strategies are based on simplicity. While carrying forward this quotation in this article I am going to present my research & observation’s on DIVERTLESS SERPENTILE duct or D-S duct.

S-duct or SERPENTILE duct is recently used in very limited fighter aircrafts & have a great scope in future of aeronautics with minimal disadvantages. S shape duct were initially came to existence in “ Trijets” but due to its complexity many commercial airlines industry drop the idea of s duct. So basically S -duct comprises the shape of serpent (snake) that’s why it usually called SERPENTILE duct . If you cut the S duct from Both the ends to its half then u will find its symmetric in nature. Unlike S-duct , D-S duct is asymmetric in nature & more like De -Laval nozzle due to its high offset at the end to supply adequate air
pressure for combustion.

In most of the fighter aircraft’s still diverters are used in inlet like Hydraulic Actuators which not only acquires lot of space but also made aircraft heavy & less Maneuver. D-S duct didn’t use any kind of moving
parts like Hydraulic or pneumatic actuators rather it uses a set of bumps & microjets . Due to its ultra compact design it blocks the radar to reach the front part of the engine which increases aircraft stealth capability & reduces RCS (radar cross sectional area) because the spinning compressor blades would produce a strong radar return & can detect easily . I have designed a D-S duct which uses microjets to improve & control the flow uniformity throughout the duct without any major loss. Microjet’s remain closed during transonic flights & once it reaches supersonic speed then microjets came into action.

It opens automatically & deliver’s the adequate amount of air pressure to reduce the supersonic airflow to subsonic. Thus it helps in noise reduction which ultimately increase in control flow & shock resistant. After crossing Mach -2 the Microjets change there orientation & allows more air to pass through it such that it will increase the air pressure in the duct & engine overall efficiency & if my calculation’s are not wrong then a fighter aircraft with D-S duct can attain Mcruise 1.5-1.8 without any afterburners “It Sounds great” right but there is lot more we have to take care of. Due to its compact size it can be fitted easily & allows aircraft to be more complex stealthy design & lightweight . D-S duct is not only limited to fighter Aircrafts but can also be used in UAV (unmanned aerial vehicle) . It is believe that in the new Era the air-warfare would be done by the UAV’s using specialised artificial intelligence (AI) . The material that can be used for making D-s duct is all Carbon – composites. Carbon composites are light in weight & have very high melting point & can resist large amount of shock too & in addition we can add CARBON LINING on the inner surface of Ds duct which helps in either absorbing or decreasing the RCS ( radar cross section ). Now due to its high specific impulse it’s help engine to generate large amount of thrust in very short duration of time which enables aircraft with D-s duct can be used in naval forces too in aircraft carriers.

So far we know about it’s countless number of advantages but then question arises why still S-duct are used only in few aircraft’s?. So the main reason behind this is of it’s complex design . S-duct are usually expensive & complex than any other types of duct . SERPENTILE duct creates distortion at different aerodynamics interface it can be uniform at specific angle of attack & increases distortion at minimal angle 2 deflection’s. For maintaining the optimal pressure gradient we can turn the duct 45° at a time after that total pressure gradient is reversed however there is no distinct loss were there in D-S duct . Now due to its high offset , variable distortion , ultra compact creates difficulties in design but that’s not the major problem too ,it is the engine that we have to re-design & which is compatible of D-S duct is the real issue . However we can control its flow by using bumps that enable only adequate amount of airflow inside the duct & deflect Obligue & Normal shock to prevent any catastrophic failures. Microjet’s are capable of control the flow inside the duct whenever it’s required. D-S duct is one of its kind although it is difficult to design & test practically but we can easily do analysis on D-S duct by using Dassault CATIA, ANSYS, solid works, AUTODESK & on other supercomputers which provide the detailed information regarding how D-S duct work in reality . I have already made a 3d model using CATIA & Microsoft 3d which provides you rough idea that ..
How it will look virtually…

DS Duct
DS Duct

At this stage we can just predict the performance of D-S duct & who knows about 60 years from now Indian fighter aircraft using the same technology . We don’t know when all these observations completes but we definitely know from where to start . Science has no boundary whatever we invent today it becomes history for our future generation. For a time being with this little amount of knowledge I can deliver this much on D-S duct but no worry cause “Imagination is more important than Knowledge” – Albert Einstein.

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