!nostupidquestions is a community dedicated to being helpful and answering each others' questions on various topics.
The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:
Rule 1- All posts must be legitimate questions. All post titles must include a question.
All posts must be legitimate questions, and all post titles must include a question. Questions that are joke or trolling questions, memes, song lyrics as title, etc. are not allowed here. See Rule 6 for all exceptions.
Rule 2- Your question subject cannot be illegal or NSFW material.
Your question subject cannot be illegal or NSFW material. You will be warned first, banned second.
Rule 3- Do not seek mental, medical and professional help here.
Do not seek mental, medical and professional help here. Breaking this rule will not get you or your post removed, but it will put you at risk, and possibly in danger.
Rule 4- No self promotion or upvote-farming of any kind.
That's it.
Rule 5- No baiting or sealioning or promoting an agenda.
Questions which, instead of being of an innocuous nature, are specifically intended (based on reports and in the opinion of our crack moderation team) to bait users into ideological wars on charged political topics will be removed and the authors warned - or banned - depending on severity.
Rule 6- Regarding META posts and joke questions.
Provided it is about the community itself, you may post non-question posts using the [META] tag on your post title.
On fridays, you are allowed to post meme and troll questions, on the condition that it's in text format only, and conforms with our other rules. These posts MUST include the [NSQ Friday] tag in their title.
If you post a serious question on friday and are looking only for legitimate answers, then please include the [Serious] tag on your post. Irrelevant replies will then be removed by moderators.
Rule 7- You can't intentionally annoy, mock, or harass other members.
If you intentionally annoy, mock, harass, or discriminate against any individual member, you will be removed.
Likewise, if you are a member, sympathiser or a resemblant of a movement that is known to largely hate, mock, discriminate against, and/or want to take lives of a group of people, and you were provably vocal about your hate, then you will be banned on sight.
Rule 8- All comments should try to stay relevant to their parent content.
Rule 9- Reposts from other platforms are not allowed.
Let everyone have their own content.
Rule 10- Majority of bots aren't allowed to participate here.
Our breathtaking icon was bestowed upon us by @Cevilia!
The greatest banner of all time: by @TheOneWithTheHair!
I'm guessing you probably don't have the air intake part of the equation. A lot of newer, more powerful hoods require an air exchanger that blows in outside air to equalize the pressure from the hood blowing air out.
The faster the hood blows, the more it struggles to pull air as the pressure in the room drops. An exchanger fixes that.
At worst though, it should be pulling in as little air as when on low, not less.
I think it initially does, but then the difference in pressure basically works against it, as the pressure inside drops
Fan blades are basically spinning wings or airfoils.
Depending on their design or how expensive they are, they may rely on pushing air rather than aerodynamic effects at low speeds, and they’re always optimized for a specific rpm.
As it speeds up, the aerodynamic flow takes over, with the rotors creating a pressure differential that pulls air through.
As it gets faster and faster, eventually, that pressure differential reaches the next rotor and the entire thing stops being as effective because now the the second rotor is stalled out. (Only they’re all stalled out because any given rotor is both leading and trailing.)
Said another way, each rotor is passing through the wake of the previous rotor and not pushing more air because the air is already moving with the wing.
I like this answer. The only thing I would add is that when the fan blades are all stalled, it might seem then that drag and energy consumption should reduce, since there's not much air moving. But in a cruel twist (fan pun intended) of aerodynamics, the useless spinning of stalled fan blades still causes parasitic drag. So not only does the fan not move air, it's also consuming more energy than spinning a solid disk of the same moment-of-inertia.
When the engine fails for certain single-propeller aircraft, there's sometimes a mechanism to lock the propeller to make it stop rotating, since it would otherwise "windmill" in the air and waste the previous kinetic energy that's keeping the plane aloft. Or so I'm told.
That could happen with propellors that have Constant Speet Units. (Propellor pitch is able to be changed) The act is called 'feathering' . This can happen on multi engine aircraft and reduce the drag of the side with the failed engine. Cheaper propellors are fixed pitch and no means exist to change them. (I believe some propellor are able to have their pitch changed by a maintainer on the ground so the aircraft can be optimized for climbing, cruising or a combination of both)
'Reverse Thrust' is also possible in so e Other aircraft. the blade reverses to the point where it pushes the wrong way so the engines assist breaking* after landing. * Typo, but I'm leaving it in =)
Constant Speed is probably what I was thinking of. And speaking of multi engine failure, you've just reminded me of the demise of TransAsia Airways Flight 235 where the right engine feathered itself erroneously, but then the crew misdiagnosed the situation and shut down the left engine. Mentour Pilot made a video on that particular accident.
that's a great addon, thank you.
Side note; that's why they get noisier, too.
This was a really good explanation. Ty
Does it exhaust through the wall or just back into the room? Is is set up right?
Every microwave hood that’s come with the apt or home I’ve had has always been installed wrong and has been blocking airflow.
It's in an apartment so that might be it.
Not exactly a scientist, and I agree with the other long answer about blades disrupting each other, so I'm replying to see if I can help you visualize/understand some of the forces at play.
My source is a Tom Clancy book about a sub war.
Typically the subs are stealthy, however if I remember correctly, I'd they decided to gun the engines (think something like 105% on the reactor), they could spin the blades really fast.
But compressing the water as the blade spins makes some of it high pressure and the other side of the blade low pressure.
This would reduce the pressure low enough that the water would become a gas and in doing so, make a lot of noise and was called cavitation.
When the sub commander did this, it did mean the ship could go very fast, but was noisy as hell and anyone near would know they were around, but if someone shot a torpedo at you and you had to get out of range.....
Before readying the other reply I thought something like this might have happened and disrupted the smooth laminar airflow.
I know aircraft have over speed and under speed warnings for propellors too, but I thought that was more to do with not breaking them than 'grabbing the air ' efficiently. Supersonic propellor tips aren't a good idea.
Cavitation occurs in a liquid. When you’re pushing air, you may bump into other types of problems like stalling. If the fan is connected to a pipe, you can also get repeating surges of airflow.
Maybe the output side is clogged up and the attempt to push more air through than it can handle causes turbulence that results in slower air flow, or affects what air it is sucking up so that it pulls more from the sides rather than below.
Have you tried changing the filters?