I did, and browsed several papers that talked about greater pressure recovery with different bumps, and at different speed envelopes.
To use your method of using one article as proof of universal truth:
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J-10 Thread III (Closed to posting)
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I did, and browsed several papers that talked about greater pressure recovery with different bumps, and at different speed envelopes.
To use your method of using one article as proof of universal truth:
MiG-29
Banned Idiot
Intakes are devided by two main criteria:
Number of oblique or normal shocks they create and position.
A three multishock intake has an average pressure recovery of 95% at Mach 2, a four multishock is even higher 98% or more at Mach 2, however they are varible geometry intakes.
Position is to allow better AoA handling ot yaw angle.
87% of pressure recovery is low, and it will stall the engine fan creating structural problems and flame outs.
Engines have parameters and the manufacturer will specify max pressure recovery losses acceptable for operational service.
By having 87% pressure recovery rates at Mach two means you are reducing static thrust.
At high altitute the loses will be higher, so your fighter will lose speed and altitude, F-16 has a max ceiling lower than other fighters for that reason, fixed intake.
J-10B has better stealth but at a price.
I guess scientific papers are only sacred truth when you're posting them *rollseyes*.
Anyways, we're not disputing you on the basic science, but on your presupposition that you can't design a DSI to have better pressure recovery. Again, not all inlet and bump geometries are the same.
Btw, your nice little diagram a few posts back measure pressure recovery by oblique shockwaves generated by both external and internal geometries. Nothing precludes a diverterless inlet from having further internal geometries that generate additional shocks.
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Just to butt into a conversation here that I have little or not interest in...
you can design a DSI for a different operating mach range. that's not a problem.
after Mach 1 the math stay more or less the same, there is no qualitative changes.
on the whole airplane system side of things, even if a particular DSI design's pressure recovery let's say can only get into 99% of a "optimal" circular intake with a shock cone. at 1.8 and above. the other advantages (weight/complexity/better pressure recovery at lower mach/ alpha/beta distortion advantages) that may put it over the top vs the alternatives.
don't forget the airplane never flys at your optimal mach at a optimal beta/alpha.
with a alphabeta distortion you may find your pressure recovery number go much worse than a ideal shock geometry.
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Engineer
Major
You meant reduce the amount of weight.
J-10A doesn't create 4 shocks in the first place, so any comparison against F-14 or talk of reach M2.34 is irrelevant. The variable-geometry-inlet used on the J-10A is similar to that of F-4 Phantom:
For DSI, pressure recovery coefficient is higher than 0.91 at M0.8. At M2.0, the coefficient decreases to 0.87. This means the slope is higher than that of F-4D in the following graph, implying pressure recovery coefficient of DSI is better than the variable-geometry-inlet on F-4D:
This reflects that DSI on J-10B actually achieves slightly better pressure recovery coefficient than J-10A. The fact that PLAAF inducts J-10B into service also shows that there isn't any loss of performance in J-10B.
The J-10B being inducted has the DSI intake modified to sharpen the corners, leading to pressure recovery coefficent approaches 0.9 at M2.05, increasing the speed (as compared to J-10A) by 4%:
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Engineer
Major
This. Shape of the lip has influence on the performance as well. A lot of attention has to be spent in this area:
another thing one want to mention is fore-body compression.
which is not insignificant on J-10.
before the air hits the inlet, vs freestream air, the compression ratio actually could be higher than 1 due to fore-body effectcs.
previous generation of fighters prob don't take advantage of that effect. while F-16's generation does.
MiG-29
Banned Idiot
look, the whole point of intakes is the speed you want to fly and the efficiency and reliability of your engine.
As the air is brought from free stream to the compressor face, the flow may be distorted by the inlet. At the compressor face, one portion of the flow may have a higher velocity or higher pressure than another portion. The flow may be swirling, or some section of the boundary layer may be thicker than another section because of the inlet shape. The rotor blades of the compressor move in circles around the central shaft. As the blades encounter distorted inlet flow, the flow conditions around the blade change very quickly. The changing flow conditions can cause flow separation in the compressor, a compressor stall, and can cause structural problems for the compressor blades. A good inlet must produce high pressure recovery, low spillage drag, and low distortion.
The
inlet cowl of this DSI is designed with a forward sweep that facilitates
the diversion of the boundary layer(14) as well.
This means as the bump is fixed, so its cowl lip, therefore the J-20 or F-35 have fixed intakes.
this holds true for the F-35, J-20 J-10B or JF-17
there rest is up to you, want to believe the paper okay
Did you just ignore i.e. and Engineer? I'm honoured. Let's put this in simple terms. The inlet isn't the only factor that determines total pressure recovery to the engines.
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