Indian Hypersonic Propulsion Developments


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End of dominance of Aircraft carriers. Though, those flimsy Chinese carrier never a threat, any future Chinese carrier or possible misadventure by US like sending seventh fleet in past, shall be deterred by this missile.

This AShBM is probably a variant of the Agni-P which has both MIRV and MARV capability, according to a recent US DoD report. We need to double down on deploying a space based ISR network for accurate targeting at long ranges across the IOR.

The good news is many private cos like Pixxel Space and Galaxeye are stepping up to the challenge. The IAF has even signed contracts for small sats with them. Newspace' HAPS demonstrator has already flown so that's another broad area maritime surviellance option.

Once it's in place, we should also do a well-publicized SINKEX to demonstrate its capability and send a very clear message to all our foes/potential foes.
 
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India joins US, Russia, China hypersonic Missile club

Government sources said that the DRDO will have the capacity to develop a hypersonic missile with scramjet engine in next five years.

Updated: Sep 07, 2020 13:06 IST
By Shishir Gupta, Hindustan Times New Delhi
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The design of the HSTDV tested by India on Monday. (Pic: DRDO)

India on Monday become the fourth country after US, Russia and China to develop and successfully test hypersonic technology from APJ Abdul Kalam testing range (Wheeler Island) in Balasore, Odisha, paving the way towards development of missiles travelling at six times the speed of sound (Mach 6).


The test of Hypersonic Test Demonstrator Vehicle (HSTDV), developed by Defence Research and Development Organisation (DRDO) was conducted at 11: 03 am today and lasted for five minutes using Agni missile booster.

According to top government sources, this means that the DRDO will have the capacity to develop a hypersonic missile with scramjet engine in next five years, which travels at more than two kilometres per second. The test was led by DRDO Chief Satheesh Reddy and his hypersonic missile team. The HSTDV performed on all parameters including combustion chamber pressure, air intake and control guidance.

At 11:03 am, an Agni missile booster took the hypersonic vehicle to height of 30 km after which the latter separated. Thereafter, the vehicle’s air intake opened and that led to successfully firing of the test scramjet engine. The combustion lasted for more than 20 seconds with the vehicle achieving a speed of six Mach. “The vehicle performed successfully on all the pre-determined parameters including the ability to handle combustion temperatures of over 2500 degrees Celsius as well as air speed,” said a senior official.

Defence Minister Rajnath Singh congratulated the DRDO immediately after the test and praised their efforts to indigenously build a scramjet engine.


Which Hypersonic (Scramjet Powered) vehicle does China have?
 
DRDL to start the 𝗗𝗲𝘀𝗶𝗴𝗻 𝗮𝗻𝗱 𝗔𝗻𝗮𝗹𝘆𝘀𝗶𝘀 𝗼𝗳 𝗥𝗶𝘃𝗲𝘁𝗲𝗱 𝗙𝘂𝗲𝗹 𝗧𝗮𝗻𝗸 configured as airframe section for the Project 𝗘𝗧-𝗟𝗗𝗛𝗖𝗠 for realizing 𝗛𝘆𝗽𝗲𝗿𝘀𝗼𝗻𝗶𝗰 𝗖𝗿𝘂𝗶𝘀𝗲 𝗠𝗶𝘀𝘀𝗶𝗹𝗲 𝗳𝗼𝗿 𝟭𝟬𝟬𝟬𝘀 of flight. The cruise vehicle is configured with metallic airframe protected by TPS.

 
A few old photos & diagrams from DRDO's Scramjet test stand.
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The test stand has a multi-strut based supersonic combustor. The schematic of the combustor is shown below:
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As the schematic shows the combustor is divided into multiple sections each housing a symmetric array of struts. According to position the struts are given a Stage number. A strut is an angular device often used in aviation industry with the intention of bifurcating stream lines. Depending on the shape & size struts may be used to control turbulences, generate lift or drag etc.

In this case however struts are used as fuel injectors. So the struts will slice the supersonic stream inside the combustor & inject fuel into the stream. Thus these struts will be subjected to incredibly high pressures & temperatures during the operation of the scramjet. This posed a challenge of materials, an appropriate alloy had to be chosen for making the struts.

This is how DRDO described the material selection for a series of ground tests of the scramjet engine :
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The engine was lit for 20 seconds using refined Kerosene as fuel & with Mach 2 as combustor entry speed. Remember this is from a paper published a few years back. The problems described here are solved. DRDO eventually settled on Nimonic C-263 alloy to make the struts. The alloy was further modified by DMRL before undertaking the flight test that last year. The combustor casing was made of an unnamed Nickel-based alloy.

The design of the struts were also a challenge. The struts faced very different pressures & temperatures depending on where they were placed. The Stage-I struts were subjected to a cooler undisturbed flow of air. Thus they did not need any additional cooling.

STAGE-I strut :
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The Stage-I strut is the only un-cooled strut in the entire configuration. The leading edge radius is R1.5 with θwd =12°. A total of 110 injector holes are used, each of 0.5 mm diameter. The fuel injection happens in the direction perpendicular to the flow.

STAGE-II/III struts :
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Stage-II & III struts have a common design. These are cooled struts with two-passages for the fuel to flow through them which act as a heat exchanger. The cooling is done by the Kerosene fuel itself. These struts also have 110 injector holes of 0.5 mm size. Perpendicular fuel injection pattern has been employed to inject the fuel.

Here is a photo of one of the Stage-II after the 20 sec ground tests :
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The photo shows that the nose of the strut has undergone a significant degree of ablation. The strut survived the tests & remained thermo-structurally safe to be used for longer duration tests.

During later stages of ground tests when the size of the scramjet combustor was increased there was another stage of struts that was included.

STAGE-IV struts :
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This is the newest addition to the family & carries the most complex design of them all. The trailing edge of the strut features a series of alternating wedges. The injection hole are made on the trailing edge, thus the fuel injection happens in the direction of the flow. Though exact numbers are unknown, the number of fuel injection holes are less than Stage-II/III.

Here is the general flow path configuration used for both simulations and ground testing :
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The revised arrangement of the struts :
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A new middle wall was introduced which allowed increasing the number of struts. Notice how there are 2 Stage-I struts instead of one. Increased fuel injection is needed for increasing the speed of the vehicle but it comes with problems. Increased number of struts & more injected fuel means significantly higher temperatures. Thus these modifications are introduced only after some breakthroughs have been made on the materials research side.

Here is the newer wind tunnel test model :
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pic is from a past seminar , this is the DRDL grant based project to build the scramjet engine via 3D printing method, TCS as consultant with IIT Hyderabad. They will build the full machine and transfer know how to DRDL together. Project grant was in 2021.

Interesting side note, TBRL has also granted a similar 3D printer making project to the same IITH group this year, not sure for what application.

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