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The natural gas combined cycle combustion turbines at the power plant my father works at have actively cooled turbine blades and stators. Basically, each blade/stator has tiny air bleeds in the leading edges, fed with compressor bleed air, which forms a boundary layer on the blade, allowing higher turbine inlet temps, without making things all melty. I'm not sure, but I dont believe there are any aviation engines that do this, since at those scales, the bleeds would have to be impractically small.
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Jul 20, 2013 15:01
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It is pretty common actually. https://www.youtube.com/watch?v=7upnkrhqRWQ EDM drilling can make pretty tiny holes very deep in hard materials. https://www.youtube.com/watch?v=Z5WZqYl_aZ8
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Jul 20, 2013 15:12
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helno posted:It is pretty common actually. To be fair, all the aviation turbines I've seen disassembled were 35+ year old designs. 
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Jul 20, 2013 15:14
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Previa_fun posted:
Flow goes from left to right in this picture, since the steam expands to do work on the turbine, rather than the turbine working the steam to compress it.
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Jul 20, 2013 16:41
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That picture is actually an industrial gas turbine. A steam turbine would have a way higher expansion ratio and the smaller blades would be impulse blades rather than reaction.
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Jul 20, 2013 16:50
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If you wanna know about forcing air through turbine blades, which is common, it is called impingement cooling.
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Jul 20, 2013 17:16
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There was also a Power Point presentation I saw out of I think Iran of all places - they had a power plant where something extremely bad happened - the generator was absolutely destroyed, and at some point it looks like the shaft coupling snapped off between the compressor and the generator. When the coupling broke it crashed through a brick wall, knocked over a heavy control cabinet (looks like PLC and relaying), and landed on the other side of the room. EDIT: Found it. Oh, that trashed generator makes me want to cry...
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Jul 20, 2013 18:39
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Well if we're talking about turbine failures... Here's a sneak peek: 
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Jul 20, 2013 19:38
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Hahaha, they couldn't just drop something dumb, it had to be the most delicately balanced component in the entire plant, and then they had to drop it the one place where it shouldn't be dropped. I'm pretty sure you could send every dude working on that move on a year's paid leave and still come out way ahead.
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Jul 20, 2013 20:53
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jammyozzy posted:Well if we're talking about turbine failures... Yeah, that one is, just, wow. The wiki doesn't really do much to give you a sense of scale, but this set of photos in the external links is mind-boggling. bolind posted:Hahaha, they couldn't just drop something dumb, it had to be the most delicately balanced component in the entire plant, and then they had to drop it the one place where it shouldn't be dropped. Pretty sure there wasn't any human error involved there, it looks and sounds like the hoist just plain catastrophically failed (maybe whoever was responsible for inspecting and/or maintaining the hoist might have done something dumb). They didn't "drop" it, it just "dropped." This is definitely why you never want to walk under a load! Farmdizzle fucked around with this message at 01:02 on Jul 21, 2013 |
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Jul 21, 2013 00:55
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Farmdizzle posted:Yeah, that one is, just, wow. The wiki doesn't really do much to give you a sense of scale, but this set of photos in the external links is mind-boggling. The surveillance camera footage is pretty 
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Jul 21, 2013 03:11
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Devyl posted:The surveillance camera footage is pretty "gently caress gently caress, what do we do with this half opened security gate  "
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Jul 21, 2013 03:14
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Previa_fun posted:
What's that from? any more info?
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Jul 21, 2013 05:11
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Tineye says it is a Siemens industrial gas turbine being assembled in Europe.
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Jul 21, 2013 05:13
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Used Sunlight sales posted:What's that from? any more info? Afraid not, just a random GIS result for "heavy duty gas turbine."
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Jul 21, 2013 05:24
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IPCRESS posted:Near total failure of the ROPS I thought the rollers on those were filled with water if so leaning to far to one side could tip it over.
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Jul 21, 2013 08:11
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e: nevermind
jamal fucked around with this message at 09:33 on Jul 21, 2013 |
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Jul 21, 2013 09:27
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  Horrible rotor retaining bolt failure. 2001 325 touring. I had noticed that under heavy braking I'd get a clunk and a pull to the passenger side. Finally got tired of it and pulled the wheel. Not sure I'm even glad I did. 
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Jul 21, 2013 18:51
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SuperDucky posted:
How would that cause a noise / pull?
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Jul 21, 2013 19:35
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EVERYWHERE 
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Neither of my cars have retaining bolts on the rotors. The wheel nuts hold them in place through the wheel. I'm not sure what the purpose of the retaining bolt is, other than perhaps convenience when working on the callipers. Not that it's much trouble to just take the loose rotor off...
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Jul 21, 2013 20:48
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xp67 posted:Neither of my cars have retaining bolts on the rotors. The wheel nuts hold them in place through the wheel. I'm not sure what the purpose of the retaining bolt is, other than perhaps convenience when working on the callipers. Not that it's much trouble to just take the loose rotor off... It's because BMW's have wheel bolts instead of studs so without that retaining bolt, putting a wheel on can be a royal pain if the holes happened to have shifted.
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Jul 21, 2013 21:10
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Slavvy posted:It's because BMW's have wheel bolts instead of studs so without that retaining bolt, putting a wheel on can be a royal pain if the holes happened to have shifted. Yes, but that still doesn't explain a noise. Unless the bolt failed previously and prevented the rotor and wheel from be seated properly. But once it's together it does nothing ...
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Jul 21, 2013 21:16
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If the wheel bolts were loose enough to allow the brake disk to move slightly, that'd cause a noise under braking. Though you should see corresponding damage on the bolts if that were the case, and I can't see how they'd stay on if they were that loose.
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Jul 21, 2013 22:06
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If the wheel lugs were that loose you'd have bigger problems than some sound under braking.
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Jul 21, 2013 22:11
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BlackMK4 posted:If the wheel lugs were that loose you'd have bigger problems than some sound under braking. 
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Jul 21, 2013 22:18
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Not a failure yet, but pretty bad neglect. I've owned the car for the last 50,000 miles of the 170,000 on it. It used to be my parents' and my dad did all the work, then I took it. I've gradually started doing my own work on it and finally got around to changing the front and rear differential oil. Turns out my dad never changed the oil, either. That's 170,000 miles worth of metal flakes.
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Jul 21, 2013 23:14
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SuperDucky posted:
 You either have something else wrong or the disk is moving around slightly on the bolts. How come the clearance holes in the disk are so much bigger than the threaded ones behind? That's far more than a clearance fit on even the shoddiest commercial parts. 
jammyozzy fucked around with this message at 23:26 on Jul 21, 2013 |
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Jul 21, 2013 23:16
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Slim Pickens posted:Not a failure yet, but pretty bad neglect. I've owned the car for the last 50,000 miles of the 170,000 on it. It used to be my parents' and my dad did all the work, then I took it. I've gradually started doing my own work on it and finally got around to changing the front and rear differential oil. That doesn't look bad at all for that kind of mileage. jammyozzy posted:
I think it's an illusion caused by the rotor rotating following lug nut removal. That's what makes cars without some pinning mechanism for the rotors a pain in the rear end to get the lug bolts back on (Audi/VW, et al).
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Jul 21, 2013 23:24
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Slim Pickens posted:Turns out my dad never changed the oil, either. That's 170,000 miles worth of metal flakes. haha, you think ANYONE actually changes their differential oil except rednecks with offroad trucks and car enthusiasts with track cars. You're probably still doing better than about 75% of people who have differential oil to change.
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Jul 21, 2013 23:55
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kastein posted:haha, you think ANYONE actually changes their differential oil except rednecks with offroad trucks and car enthusiasts with track cars. Well that's good to know. I didn't even know it needed changing til I looked through the Haynes manual, and had a hard time finding the dipstick because it was blackened with oily dust.
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Jul 22, 2013 01:36
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jammyozzy posted:
The holes don't really matter that much on a rotor. The hub, rotor, and wheel are held by friction joints, so the bolts shouldn't see that much shear. BMW wheels and rotors are hub centric, so the holes don't locate either. If the bolts were in shear, I'd find a critical fastener shearing on threads to be a poor design.
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Jul 22, 2013 01:54
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Today I learned that E46 drain plugs break like this (not my picture): Story is the guy got his oil changed at my store a couple months back, and it's been dripping oil from the plug ever since. Went to remove it today to check the gasket, and it fell out looking just like that picture, leaving the rest of the shaft in the hole. Turns out that's by design, apparently BMW had issues with pans getting destroyed by overtightening so they designed the drain plugs to break clean like that before the threads deform and pull the threaded insert out when you remove it (or get pushed into the pan which is its own headache.) Removing the shaft is simple, they pre-drill a hole through the entire plug so when it breaks off the oil drains through the shank, then you just hammer an allen wrench into it and turn to remove the broken plug. So... score one for superior German engineering I guess?
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Jul 22, 2013 01:58
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Fucknag posted:Today I learned that E46 drain plugs break like this (not my picture): They aren't the only ones, I've seen several brands with hollow drain plugs designed this way, generally on alloy sump engines only though.
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Jul 22, 2013 02:12
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Ford modular engine drain plugs have a similar idea, in that the threads stretch and deform if you so much sneeze on the wrench while tightening them. I'm pretty sure at least 95% of the plugs I've pulled out and they're stripped are off modulars (or alloy-pan V6s, which use the same piece.)
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Jul 22, 2013 02:15
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Much better than the alternative of having to drill/tap or replace the oil pan. It's the best idea I've read about all week.
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Jul 22, 2013 02:17
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E46 fuckery As it sits right now, if I yank on the rotor back and forth, it has about 1.5-2 inches of play without the lug bolts in at the apex of the rotor, away from the caliper. Basically, the caliper is holding it in. They weren't specifically tight like you'd want them to be. I can only theorize that the rotor was shifting versus the hub, causing the chamfering you see on the rotor around the lug holes. So, when moving along at highway speeds, it was kinda floating back and forth. Then, when the caliper exerted pressure on the rotor, it snapped back into whatever position provided for the least exertion. I really can't describe it any other way, I've never experienced anything else pedal feel wise in brakes before. Also, getting the wheel back on so I could roll it back out of the garage so I can put the car away until I can gently caress with the stripped bolt was a gigantic pain in the rear end, moreso than getting those things in is than normal.
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Jul 22, 2013 02:19
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Tactical Bonnet posted:Much better than the alternative of having to drill/tap or replace the oil pan. It's the best idea I've read about all week. Oh I agree. I've replaced dozens of drain plugs on Escapes/Tributes with the V6, I've replaced a pan exactly once (and removed another to do the gasket). Pain in the rear end. What's really awesome is when the steel thread insert cracks and half of it screws out with the plug, and the rest falls into the pan. 
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Jul 22, 2013 02:20
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SuperDucky posted:
I've had an unseemly number of BMW's, all with the same setup, and not having the little bolt in there makes no difference whatsoever to the pedal feel. Are you sure the lug hole chamfering isn't there from the factory anyway? It looks like it is, and that the rotor is incorrect for the car. What you're describing sounds more like pads loose in the carrier or a suspension related issue, there is no way the rotor can 'move around' with the wheel clamping it in and the bolts in place, it isn't possible. There's a deeper issue at play here somewhere.
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Jul 22, 2013 03:47
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SuperDucky posted:
It's not your brake discs. As mentioned before, the discs are sandwiched in place between the wheel face and the hub. Nowhere for them to go. The enlarged holes are normal. On an e46, I'd be looking at, in order of likelihood: -Control arm bushings, aka lollipops. They wear out and let the wheel wander. When you replace them, you'll wonder why you hadn't sooner. -Control arm ball joints. -Tie rods -Brake issues within the caliper, such as wrong pads or worn slide pins. If you're really unlucky, it could be rear subframe failure, but that doesn't usually manifest like this.
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Jul 22, 2013 03:49
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charliemonster42 posted:-Control arm bushings, aka lollipops. They wear out and let the wheel wander. When you replace them, you'll wonder why you hadn't sooner. This. Your FCABs are toast. Your rotor retaining bolt has gently caress all to do with your problem.
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Jul 22, 2013 04:55
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