Indian Hypersonic Propulsion Developments

Saaho

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Dec 27, 2019
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There are four main development milestones to a SCRAMjet powered hypersonic "vehicle".

1. Aerodynamics of vehicle.
2. SCRAMjet test on ground.
3. SCRAMjet test in flight without production of a net thrust.
4. SCRAMjet thurst producing tests in test flight.

India has completed Aerodynamics and initial SCRAMjet tests on ground and with today, at least one successful SCRAMjet test in flight. DRDO is not very open if it was a flight with SCRAMjet producing a net thrust or not. Soooo......

If it was a flight in which a net thrust was produced then we are at a stage equivalent to US (NASA) in 2004, parallel to their X-43A test.

If it was a flight in which a net thrust was NOT produced and this test was "merely" a captive test then this is equivalent to 1994-5 US-Russian-French JV SCRAMjet test (Kholod test).

The reason why the vehicle may not be producing a net thrust is because of drag. A fast moving hypersonic vehicle faces massive drag due to viscosity of air itself, which is proportional to square of relative velocity.

Hence it is possible for a vehicle to have a SCRAMjet engine without getting a net thurst to move it forward. Such a vehicle will loose velocity and hence the SCRAMjet will cease operation. One way around this, to only test the supersonic engine (rather combustion) by testing it in a falling object.

Australian HyShot and ISRO's SCRAMjet test were essentially testing using a sounding rocket and were such tests besides Kholod from Russia.
 
Last edited:

hellbent

Senior member
Dec 4, 2017
645
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Difference between initial HSTDV launcher and the redesigned HSTDV launcher - caged interstage either replaced or covered up . Maybe it was the reason for the alleged first test failure of the launcher few months back due to possibly bad aerodynamic interaction.

Add8-01.23.45.jpg
 

TARGET

Well-Known member
Dec 2, 2017
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A well-written article... kudos to the author, while reading you can feel like watching an Indian patriotic movie. I thought the vehicle was using kerosene but it is ethylene.
 

Gautam

Team StratFront
Feb 16, 2019
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Posted this on twitter and a lot of people started complaining that I have revealed some secret information. Just to be clear this is open source and was published openly in 2015. More than 5 years down the line an open source document is "secret" ? Come on, in all due probability this study was old news before it was officially published. Anyway here we go...........


DRDO conducted studies on scramjet combustor with alternating wedge shaped strut fuel injector. The tests were conducted at Mach 7, the recent HSTDV flight test was conducted at Mach 6. The tests were done at 3 angles of attack ( α = −3°, α = 0°, α = 3° ).

The results show that the geometry with negative angle of attack (α = −3°) have lowest ignition delay and it improves the performance of scramjet combustor as compared to geometry with α = 0°, α = 3°. The combustion phenomena and efficiency is also found to be stronger and highest in case of α = −3°.

The placement of the Combustor:
Screenshot (66).png


Full view of the entire combustor/fuel injector arrangement :
Screenshot (67).png


Test model used for the simulation study :
Screenshot (68).png


The strut design. The holes are fuel injectors. The wedges are to create compression shock wave behind the strut. When the shock waves converge they will greatly increase the temperature and create conditions conducive for Ethylene ignition and combustion :
Screenshot (69).png


From the simulations :
Screenshot (70).png

Screenshot (71).png
Screenshot (73).png
Screenshot (74).png
Screenshot (75).png
Screenshot (76).png


The conclusions from the simulations are :

1. There is no impact of the wedge formed strut injector in upstream course towards the isolator when α = 0°. Meaning at α = 0°, the shockwaves created by the struts do not cause any backflow in the direction of the intake. All shockwaves are formed in the direction of the exhaust nozzle.

2. The flow properties, shock structure, mixing and combustion phenomena are exceptionally sensitive to the variation of the angle of attack. Here there is a displacement of the shock train in the upstream direction for a negative angle of attack was found. This shock displacement improved the combustion phenomena and decreased the ignition delay. This shock also helps in modifying the shock pattern in the combustor.

3. No thermal choking was found for this setup. The range increment in the different combustor is adequate to keep away from inlet instabilities.

4. The highest temperature found for a negative angle of attack α = −3° is approximately T = 2,980 K. The least ignition delay was enlisted for (α = −3°) more or less 95 mm downstream the fuel injection and longest ignition delay was found for positive angle of attack (α = 3°). The combustion efficiency is the best for α = −3°.


From the conclusions it is pretty clear that to create initial scramjet ignition just after separation of the first stage. The HSTDV is to be maneuvered to attain an angle of attack (α ) = −3°. That is the intake nose slightly pointing down. In this α we have the lowest ignition delay and the highest combustion efficiency. Once the ignition stabilizes we can go for α = 0°, as at the α we can get the maximum speed. Although speed will come at the cost of less than the optimum combustion efficiency.
 

STEPHEN COHEN

Senior member
Dec 4, 2017
5,471
3,441
Posted this on twitter and a lot of people started complaining that I have revealed some secret information. Just to be clear this is open source and was published openly in 2015. More than 5 years down the line an open source document is "secret" ? Come on, in all due probability this study was old news before it was officially published. Anyway here we go...........


DRDO conducted studies on scramjet combustor with alternating wedge shaped strut fuel injector. The tests were conducted at Mach 7, the recent HSTDV flight test was conducted at Mach 6. The tests were done at 3 angles of attack ( α = −3°, α = 0°, α = 3° ).

The results show that the geometry with negative angle of attack (α = −3°) have lowest ignition delay and it improves the performance of scramjet combustor as compared to geometry with α = 0°, α = 3°. The combustion phenomena and efficiency is also found to be stronger and highest in case of α = −3°.

The placement of the Combustor:
View attachment 17851

Full view of the entire combustor/fuel injector arrangement :
View attachment 17852

Test model used for the simulation study :
View attachment 17853

The strut design. The holes are fuel injectors. The wedges are to create compression shock wave behind the strut. When the shock waves converge they will greatly increase the temperature and create conditions conducive for Ethylene ignition and combustion :
View attachment 17854

From the simulations :
View attachment 17855
View attachment 17856View attachment 17857View attachment 17858View attachment 17859View attachment 17860

The conclusions from the simulations are :

1. There is no impact of the wedge formed strut injector in upstream course towards the isolator when α = 0°. Meaning at α = 0°, the shockwaves created by the struts do not cause any backflow in the direction of the intake. All shockwaves are formed in the direction of the exhaust nozzle.

2. The flow properties, shock structure, mixing and combustion phenomena are exceptionally sensitive to the variation of the angle of attack. Here there is a displacement of the shock train in the upstream direction for a negative angle of attack was found. This shock displacement improved the combustion phenomena and decreased the ignition delay. This shock also helps in modifying the shock pattern in the combustor.

3. No thermal choking was found for this setup. The range increment in the different combustor is adequate to keep away from inlet instabilities.

4. The highest temperature found for a negative angle of attack α = −3° is approximately T = 2,980 K. The least ignition delay was enlisted for (α = −3°) more or less 95 mm downstream the fuel injection and longest ignition delay was found for positive angle of attack (α = 3°). The combustion efficiency is the best for α = −3°.


From the conclusions it is pretty clear that to create initial scramjet ignition just after separation of the first stage. The HSTDV is to be maneuvered to attain an angle of attack (α ) = −3°. That is the intake nose slightly pointing down. In this α we have the lowest ignition delay and the highest combustion efficiency. Once the ignition stabilizes we can go for α = 0°, as at the α we can get the maximum speed. Although speed will come at the cost of less than the optimum combustion efficiency.

What will be the Range and Payload of the Hypersonic Missile
 

Gautam

Team StratFront
Feb 16, 2019
11,788
7,909
Tripura, NE, India
What will be the Range and Payload of the Hypersonic Missile
Hard to say. The project is still an engine experiment similar to the LFRJ or the SFDR. Once the engine tech is mastered various weapons can come off of it. No official data is out on fuel tank capacity or payload size.

If I were to guess, I would say the range of HSTDV based cruise missile should be greater than the old 300km ranged Brahmos. I say that as the Brahmos also has a air-breathing engine and it flies at half the HSTDV's speed. The Brahmos can hit Mach 3 in 300 kms, the HSTDV should take longer than that to get to Mach 6. Therefore onboard fuel should present be in quantities that allow greater range.

As for payload, I am not sure it will carry any. If it does it will be very small warhead. The kinetic energy alone will do devastating damage, why is a warhead needed ? We are better off putting some good sensors in the internal payload space available. Also given the speed, the computing power of the guidance and navigation system has to be very high just to keep up.
 

Ashwin

Agent_47
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Administrator
Nov 30, 2017
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India can have complete hypersonic cruise missile system in 4-5 years: DRDO

 

_Anonymous_

Senior Member
Dec 4, 2017
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Mumbai
India can have complete hypersonic cruise missile system in 4-5 years: DRDO

According to your newly discovered favorite defense analyst - PKS, That is expected to be the Brahmos -2 aka the Zircon.
 

_Anonymous_

Senior Member
Dec 4, 2017
12,401
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Mumbai
Even your clickbait youtube channels can tell you zircon is brahmos 2, Amit.
PKS- your newly discovered favorite defense analyst has been saying this for years ( since 2015 to be precise) . I guess most click bait channels took it from there.Now, since you appreciate his sense of history more than his current analysis, it must be genuine in your book.
 

TARGET

Well-Known member
Dec 2, 2017
379
303
PKS- your newly discovered favorite defense analyst has been saying this for years ( since 2015 to be precise) . I guess most click bait channels took it from there.Now, since you appreciate his sense of history more than his current analysis, it must be genuine in your book.
IF DRDO is able to bring the technology for Hypersonic cruise missile, I don't think we will go for Brahmos Hypersonic cruise missile bcoz of cost.
 

Ashwin

Agent_47
Staff member
Administrator
Nov 30, 2017
4,127
6,754
Bangalore
PKS- your newly discovered favorite defense analyst has been saying this for years ( since 2015 to be precise) . I guess most click bait channels took it from there.Now, since you appreciate his sense of history more than his current analysis, it must be genuine in your book.
I'm glad you are able to remember things that long considering you forget half the discussion here so often. Hope i won't be hearing from you about this same discovery anytime soon then.