Chinese Engine Development


Skywatcher

Captain
Have you ever heard of computer simulation software?
Basically most all designing phase testing is done with software such as Dassault Systemes Simulia ever before leaving the drawing board.
The reason why the US has been able to design and test a 6th generation fighter(within a year) so quickly is because of this kind of technology connected with super computers since the software relies heavily on the computation power.
This trend is the same with commercial automotive industry with initial design concept to proto typing within 18 months.
On the other hand, high mach wind tunnels can only provide mili-second simulations so it is very limited in capacity in testing a design.
That is the very reason why the US has not developed any new physical test facilities except for the final stage testing fascinating the final model to a hyper velocity rocket to see how it respond to the speed comparing it to the simulation.
For a revolutionary new type of propulsion, sodramjet (which hasn't been tested either in flight or on ground), it would have to be at least tested for even half a second (which is pretty darn long for a hypersonic wind tunnel) as there's absolutely no real world data to validate the software model. Otherwise no scientific or research institution in the world would have enough confidence to agree to spend at least a low eight figure USD sum to build a flying prototype.
 

latenlazy

Colonel
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^ Why CFD hasn't yet replaced WT completely.
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Not being petty or anything but these were just a Google search away. Computer Aided Simulations aren't replacing Wind Tunnels simply because algorithms haven't been trusted to accurately and precisely replicate fluid flows and dynamics.
CFDs are excellent places to start testing general ideas about flow field interactions but ultimately you always need to validate with live models. The time saving is in step and workflow reduction, as well as analysis, but ultimately you’re still going to need to tweak and adjust based on analog conditions.
 

gelgoog

Captain
Registered Member
Have you ever heard of computer simulation software?
Basically most all designing phase testing is done with software such as Dassault Systemes Simulia ever before leaving the drawing board.
The reason why the US has been able to design and test a 6th generation fighter(within a year) so quickly is because of this kind of technology connected with super computers since the software relies heavily on the computation power.
This trend is the same with commercial automotive industry with initial design concept to proto typing within 18 months.
On the other hand, high mach wind tunnels can only provide mili-second simulations so it is very limited in capacity in testing a design.
That is the very reason why the US has not developed any new physical test facilities except for the final stage testing fascinating the final model to a hyper velocity rocket to see how it respond to the speed comparing it to the simulation.

I have heard of it. CFD works like crap in highly turbulent environments like high Mach regimes.
The models fail. You can improve the models but for that you have to, guess what, get live test data to improve the models.
If you want to simulate transitions between regimes then you are SOL.

I know SpaceX made their own in-house software to do CFD simulation in order to be able to design the Raptor engine.
Not everyone can do that.
 

SamuraiBlue

Captain
I have heard of it. CFD works like crap in highly turbulent environments like high Mach regimes.
The models fail. You can improve the models but for that you have to, guess what, get live test data to improve the models.
If you want to simulate transitions between regimes then you are SOL.

I know SpaceX made their own in-house software to do CFD simulation in order to be able to design the Raptor engine.
Not everyone can do that.

Yes and the US has ample test data from the 60's, 70's and the 80's that they had collected during the various X-projects and others requiring hyper speed projectiles and flying objects.
The US designed the SR-71 supersonic planes in the 60's and flown the X-15 at speeds of Mach 6.7 in the late 60's as well.
Those data are now used to calculate simulations.
Like I posted within my original post, computer SIMULATION is used for the DESIGNING PHASE to weed out bad designs. This is the same with any other CFD projects in any industry.
Once they have reached the final stage (prototype) it is more constructive to just strap it on to a rocket and fly it at hyper sonic stage then testing it in a wind tunnel that can only give you a mili-second worth of data since that is about the only amount you can get from a hyper sonic wind tunnel. (They basically blast an explosive charge and direct the blast force towards the test piece to obtain the testing speeds so it cannot sustain speeds for more than a few mili-seconds)
 

gelgoog

Captain
Registered Member
Yes and the US has ample test data from the 60's, 70's and the 80's that they had collected during the various X-projects and others requiring hyper speed projectiles and flying objects.
The US designed the SR-71 supersonic planes in the 60's and flown the X-15 at speeds of Mach 6.7 in the late 60's as well.
Those data are now used to calculate simulations.
Like I posted within my original post, computer SIMULATION is used for the DESIGNING PHASE to weed out bad designs. This is the same with any other CFD projects in any industry.
Once they have reached the final stage (prototype) it is more constructive to just strap it on to a rocket and fly it at hyper sonic stage then testing it in a wind tunnel that can only give you a mili-second worth of data since that is about the only amount you can get from a hyper sonic wind tunnel. (They basically blast an explosive charge and direct the blast force towards the test piece to obtain the testing speeds so it cannot sustain speeds for more than a few mili-seconds)

In that case explain me this.


1607246786023.png
 

ougoah

Major
Registered Member
Wait a sec so Dr. Combs says the US has several Mach 16 capable facilities and a member here earlier claimed there is a difference between the Chinese hypersonic tunnels and the US ones. So what is the difference? Also if the American ones are much smaller and cannot even offer 50 millisecond test run up to mach 16 for short duration impulse runs, is there literature to suggest or prove this? further, is there literature to suggest Chinese and/or Russian ones can run test on models?
 

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