CNBA3 said:
Those don't look like particulates, they are usually smoke or dust, liquid droplets.
I don't know what kind of smoke you've seen before, but smoke doesn't look like that in the slightest. Her mech's explosion was more of a generic energy blast than a conventional fireball + shockwave detonation.
CNBA3 said:
In fact you can see those "particulates" before the explosion accumulating into the core, not ejected from the explosion seeing as the energy explosion was still going, which against makes sense as it was the short end of the blast
Which isn't really evidence of the explosion actually hitting her, seeing as those particles weren't even inside of the blast radius to start and could have very likely been sent out to D.Va's distance from the force of the blast.
Honestly arguing the exact mechanics of a fictional energy explosion to try and stipulate something that is actively contradicted by what's shown on screen and what's measured with better calculation methods is a waste of time and effort, IMO.
CNBA3 said:
here is an image, you can see the mech in the center.
That isn't the same shot as when it exploded. Like I already explained it cuts to and from D.Va while she's falling like 3-4 times before it actually goes off, which matters a lot as at terminal velocity her distance from the mech is drastically increasing. (Double checked, it is the same shot, but these issues still remain

Even if it's in the same shot, heck, the fact that the POV is moving with D.Va makes measured sizes wrong regardless.
So whatever you're pulling from the explosion size is inaccurate. Angsizing can make calcs stupidly wonky when done even a smidgen inaccurately, and there's good arguments that it should be avoided when clear, easier, more reliable alternatives exist for measuring when both the explosion and the distance measured is in the foreground.
The calc is bad. Not as bad as the vaporization calc earlier, but still bad. There's an already accepted calc for this explosion, and the amount of time that it took D.Va to hit the ground also contradicts any of the measurements you pulled and pictures of the full explosion.