Comments on: TAN Turbine http://selenianboondocks.com/2009/07/tan-turbine/ Random Musings from the Warped Minds of Jonathan Goff, Ken Murphy, John Hare, and Kirk Sorensen Fri, 12 Mar 2010 20:26:31 -0800 http://wordpress.org/?v=2.8.4 hourly 1 By: john hare http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5121 john hare Sun, 12 Jul 2009 09:42:21 +0000 http://selenianboondocks.com/?p=1078#comment-5121 <i>13Tim Hi John. I got to thinking about ways to minimise the velocity of the flow over the fuel grain so as to minimise errosive burning, and it struck me that since the shaft is rotating, the velocity would be minimised by a “rotating” flow, such as the “swirl” in Orbitec’s vortex engine. Could you bring the oxidiser injection from the top of the chamber to the bottom to create a vortex engine? <i> I didn't draw the shaft accurately. The shaft must be enclosed in a bearing housing all the way down to the turbine with multiple bearings. I didn't realize the misdirection until one of my friends in the business pointed that out to me off line. We went a couple of rounds before I realized that I had implied an exposed shaft. I don't see any reason the swirl you suggest couldn't be done with the injectors. I get real nervous now thinking about any solid fuel material immediately above the turbine. 13Tim

Hi John. I got to thinking about ways to minimise the velocity of the flow over the fuel grain so as to minimise errosive burning, and it struck me that since the shaft is rotating, the velocity would be minimised by a “rotating” flow, such as the “swirl” in Orbitec’s vortex engine. Could you bring the oxidiser injection from the top of the chamber to the bottom to create a vortex engine?

I didn’t draw the shaft accurately. The shaft must be enclosed in a bearing housing all the way down to the turbine with multiple bearings. I didn’t realize the misdirection until one of my friends in the business pointed that out to me off line. We went a couple of rounds before I realized that I had implied an exposed shaft.

I don’t see any reason the swirl you suggest couldn’t be done with the injectors. I get real nervous now thinking about any solid fuel material immediately above the turbine.

]]> By: Tim http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5115 Tim Sun, 12 Jul 2009 04:21:03 +0000 http://selenianboondocks.com/?p=1078#comment-5115 Hi John. I got to thinking about ways to minimise the velocity of the flow over the fuel grain so as to minimise errosive burning, and it struck me that since the shaft is rotating, the velocity would be minimised by a "rotating" flow, such as the "swirl" in Orbitec's vortex engine. Could you bring the oxidiser injection from the top of the chamber to the bottom to create a vortex engine? Hi John. I got to thinking about ways to minimise the velocity of the flow over the fuel grain so as to minimise errosive burning, and it struck me that since the shaft is rotating, the velocity would be minimised by a “rotating” flow, such as the “swirl” in Orbitec’s vortex engine. Could you bring the oxidiser injection from the top of the chamber to the bottom to create a vortex engine?

]]> By: Jörg May http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5093 Jörg May Thu, 09 Jul 2009 00:42:57 +0000 http://selenianboondocks.com/?p=1078#comment-5093 Roderick I know what TAN means, I wanted only deleting the turbin blades and shaft and keep the combustion chamber. And the solid fuel would be in separat chambers just like the picture above. Roderick
I know what TAN means, I wanted only deleting the turbin blades and shaft and keep the combustion chamber. And the solid fuel would be in separat chambers just like the picture above.

]]> By: Roderick Reilly http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5082 Roderick Reilly Wed, 08 Jul 2009 14:36:29 +0000 http://selenianboondocks.com/?p=1078#comment-5082 Jörg: It sounds like you're describing an "integrated rocket-rocket." The most basic integrated rocket-ramjet works this way, with a solid fuel charge taking up a ramjet's combustion chamber for the initial boost. But the idea of the TAN nozzle is to work like the afterburner of a turbojet engine, meaning that you add extra propellant and oxidizer to the exhaust stream already coming from the actual combustion chamber. Jörg:

It sounds like you’re describing an “integrated rocket-rocket.” The most basic integrated rocket-ramjet works this way, with a solid fuel charge taking up a ramjet’s combustion chamber for the initial boost.

But the idea of the TAN nozzle is to work like the afterburner of a turbojet engine, meaning that you add extra propellant and oxidizer to the exhaust stream already coming from the actual combustion chamber.

]]> By: Jörg May http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5077 Jörg May Wed, 08 Jul 2009 10:41:25 +0000 http://selenianboondocks.com/?p=1078#comment-5077 What if you replace the whole turbin and place solid fuel in the TAN chambers and use them for the start and the first flight phase. In the second phase the nozzle had much better efficiency. What if you replace the whole turbin and place solid fuel in the TAN chambers and use them for the start and the first flight phase. In the second phase the nozzle had much better efficiency.

]]> By: Roderick Reilly http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5062 Roderick Reilly Tue, 07 Jul 2009 16:33:04 +0000 http://selenianboondocks.com/?p=1078#comment-5062 Another fascinating subject to which I can add no technical commentary. I just like the TAN concept, and would be happy to see an operational engine of the basic vanilla version developed. Has anyone figured out if the Aerojet HC Boost is/was a TAN concept? Another fascinating subject to which I can add no technical commentary. I just like the TAN concept, and would be happy to see an operational engine of the basic vanilla version developed.

Has anyone figured out if the Aerojet HC Boost is/was a TAN concept?

]]> By: john hare http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5048 john hare Sun, 05 Jul 2009 16:34:47 +0000 http://selenianboondocks.com/?p=1078#comment-5048 Not necessarily a plug nozzle, just a ring chamber geometry with throat that takes the gas to supersonic before it enters the expansion nozzle and merges with the primary stream. It does seem likely that gas velocity in contact with the fuel grain could be low enough to discourage the chunks from erosive burning. While I had always thought in terms of regen cooling of parts in chamber, Thomas had a pretty good argument for just throwing a fuel grain around it instead and not trying to over engineer the concept. Not necessarily a plug nozzle, just a ring chamber geometry with throat that takes the gas to supersonic before it enters the expansion nozzle and merges with the primary stream.

It does seem likely that gas velocity in contact with the fuel grain could be low enough to discourage the chunks from erosive burning. While I had always thought in terms of regen cooling of parts in chamber, Thomas had a pretty good argument for just throwing a fuel grain around it instead and not trying to over engineer the concept.

]]> By: Tim http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5047 Tim Sun, 05 Jul 2009 13:05:07 +0000 http://selenianboondocks.com/?p=1078#comment-5047 Hmmm, hadn't considered the burn time, with that solid TAN thing, I figured the weight/thickness of the required coating would be what made it impractical. Out of interest, by "throat geometry to focus the energy", do you mean something like a plug nozzle? According to this site http://www.braeunig.us/space/propuls.htm#solid some fuels have a threshold flow velocity below which they don't undergo erosive burning, so it might be possible to avoid chunks in the flow. Hmmm, hadn’t considered the burn time, with that solid TAN thing, I figured the weight/thickness of the required coating would be what made it impractical. Out of interest, by “throat geometry to focus the energy”, do you mean something like a plug nozzle?

According to this site

http://www.braeunig.us/space/propuls.htm#solid

some fuels have a threshold flow velocity below which they don’t undergo erosive burning, so it might be possible to avoid chunks in the flow.

]]> By: john hare http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5046 john hare Sun, 05 Jul 2009 12:56:00 +0000 http://selenianboondocks.com/?p=1078#comment-5046 Hybrid grains are supposed to have much lower regression rates than solid fuel grains. I can't believe I didn't think about solid chunks hitting the turbine blade. SS1 had a problem with chunks even on the prize flights, so that would definately be a show stopper. TAN chambers and blade tips would be the worlds first muzzle loading rocket. That has to count for something in the museum of dumb rocket tricks, even if not in the real world. Hybrid grains are supposed to have much lower regression rates than solid fuel grains.

I can’t believe I didn’t think about solid chunks hitting the turbine blade. SS1 had a problem with chunks even on the prize flights, so that would definately be a show stopper.

TAN chambers and blade tips would be the worlds first muzzle loading rocket. That has to count for something in the museum of dumb rocket tricks, even if not in the real world.

]]> By: Eric Collins http://selenianboondocks.com/2009/07/tan-turbine/comment-page-1/#comment-5045 Eric Collins Sun, 05 Jul 2009 12:19:22 +0000 http://selenianboondocks.com/?p=1078#comment-5045 It seems to me that most ablative surfaces are designed so as to minimize the rate at which they burn through. I don't think solid rocket fuel qualifies in this regard. Given the immense size of the SRB's on the shuttle, and the fact that it only takes them a couple of minutes to completely burn out, I think you'd be hard pressed to find a fuel grain that would burn slowly enough to remain useful throughout the first stage of your flight profile, especially considering that you're talking about a much smaller volume of fuel. And if you did find something that would burn through that slowly, I'd have to wonder just how much it would actually be contributing to the engine thrust. Granted, I'm not much of an expert on solid fuels, but I was under the impression that, in most engines, there are usually chunks of solid fuel which flake off and continue to burn while still in the flow. If so, then there is probably a good chance that they could remain large enough to cause damage to the turbine at the throat. I do like that almost all of the moving parts are now outside of the main combustion chamber, but I still have similar reservations about the TAN chambers and the tips of the blades. It seems to me that most ablative surfaces are designed so as to minimize the rate at which they burn through. I don’t think solid rocket fuel qualifies in this regard. Given the immense size of the SRB’s on the shuttle, and the fact that it only takes them a couple of minutes to completely burn out, I think you’d be hard pressed to find a fuel grain that would burn slowly enough to remain useful throughout the first stage of your flight profile, especially considering that you’re talking about a much smaller volume of fuel. And if you did find something that would burn through that slowly, I’d have to wonder just how much it would actually be contributing to the engine thrust.

Granted, I’m not much of an expert on solid fuels, but I was under the impression that, in most engines, there are usually chunks of solid fuel which flake off and continue to burn while still in the flow. If so, then there is probably a good chance that they could remain large enough to cause damage to the turbine at the throat.

I do like that almost all of the moving parts are now outside of the main combustion chamber, but I still have similar reservations about the TAN chambers and the tips of the blades.

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