Gluhareff 130R power failure issue still open ... Any Idear?

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luc
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130R Power failure

Post by luc » Fri Jan 23, 2004 9:30 pm

Heyyy Guys,

I just had a good idear ...

Now that we know the performance of the Gluhareff nozzle with a gas suplly at 225 psi and 1200°F.

I will run a CFD simulation of the 2 evaporator coils at 3600°F, with liquid propane supplied at 700 psi. and see at what temperature the propane come out with.

After that, I will run a CFD simulation of the Gluey nozzle using the temperature of the previous test (Coils at 3600° under 700 psi.) under 700 psi. To see the performance (i.e: Speed, flow, temperature, pressure).

Then I will redesign and remodel the Gluey nozzle so it will give me the same performance as if it would be under 700 psi. but at 225 psi.

I think we have a plan here ....

So if some of you have a quit nozzle simulation program to do quick and preliminary sizing and shaping of the nozzle, that would give something to start with.

Anyone has one ?

Regards,

Luc

Viv
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Post by Viv » Fri Jan 23, 2004 10:33 pm

That sounds like a pretty good plan to me, at the end of the day we just want the maximum velocity out of it at a reasnable fuel flow rate to sustain combustion.

As for a nozzle program I was looking at rocket nozzle design software, this is about the best I have seen searching the web, its only $30 but I have not used it as yet so cant say if it will do the job, on the same site they also have an aerospike design program.

http://www.aerorocket.com/Nozzle/Nozzle.html

Viv
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Raymond G
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Nozzle Performance

Post by Raymond G » Fri Jan 23, 2004 11:01 pm

I did a quick hand calc for your input values of :

Throat dia=.25 in
Total Pressure= 225 psi
Total Temp= 1200 F
Fluid: Gaseous Propane
Nozzle type: Sonic

and I got:

mdot(GP)=.16 lbm/sec
exit velocity=1400 ft/sec

Note that the actuall nozzle is not a true sonic nozzle, as it has such a long throat which will cause additional sonic and boundary layer choking. This choking I did not account for in the calc above, and probably acounts for the discrepancy between this method, and the CFD result. With the reduced exit velocity, the mdot will probably reduce to about .12 lbm/sec.

Regards,
Raymond

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Post by Viv » Fri Jan 23, 2004 11:18 pm

Damn damn damn! I have been strugling to convert the numbers in this report and I just realised that I have been caught out by the Europeanese thread:-)

Its got eh "," instead of the "." now it makes a bit more sense:-)

I thought at one point the exit velocity for the propane was faster than the starship enterprise!

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Post by Viv » Sat Jan 24, 2004 12:51 pm

Ok I realy need to see a picture or a drawing of the Gluey propane nozzle as soon as possible, could some one do me a faveour and post it to this thread.

Ta muchly.

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Post by Viv » Sat Jan 24, 2004 1:18 pm

Propane at 225psi and 1200f is being fed to this nozzle, now the local speed of sound for propane at 1200f is 2381 feet per second.

But the maximum exit velocity is only 2141 feet per second in the report! using online java nozzle calculators to check figures is probably not the best solution but I am at my partners office doing this and they are all I can get too.

Now I cant help but feel that this nozzle is not cutting the mustard and there is a problem with it, I think I am going to have get my hands on a better program unless some one can see what I am doing wrong.

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Transient Responce

Post by Graham C. Williams » Sat Jan 24, 2004 1:33 pm

The following passage taken from,
Microphones
Operating Principles and Type Examples
Gerhart Bore / Stephan Peus
Published by: Georg Neumann GmbH, Berlin
www.neumann.com

shows the importance of transient response in selecting microphones for this type of recording. The difference between the dynamic microphone and the condenser is easy to see in this oscilloscope display.


It is difficult to establish clear reasons for choosing condenser microphones over good moving coil ones solely from their technical specifications. Microphones having identical frequency responses, when reproduced through first-rate systems do give distinctly different acoustical results. This is understandable, at least to some extent, if the impulse behavior of the microphone is examined.

Fig. 41 shows the output voltage of two cardioid microphones, placed at a distance of 20 cm in front of a spark gap. A capacitor discharging across the spark gap produces an extremely short pressure impulse. The voltages put out by the two microphones show great differences between them.

Fig. 41 Output voltages of two cardioid pattern studio microphones when stimulated by an electrical spark discharge (above: moving coil microphone, below: condenser microphone)

Even taking into account the fact that human hearing does not respond to phase shift of individual components in the pulse spectrum, one must note that the moving coil microphone's output shows damped oscillations occurring within the audible range, which without a doubt, produce sound coloration and may mask the directly following sound signals.

Differences in the acoustical patterns of two seemingly identically specified microphones can be caused by a differing curve for the diffuse-field frequency response. Regrettably, this is omitted from most specifications.

In addition to the parameters determining response quality, the operational characteristics play a great role in judging the performance of a microphone. Enthusiastic HiFi fans are ready to take the greatest pains when using their highly valued microphones, and, when necessary, will operate each microphone through its own dedicated cable. In professional studio environments, the technicians demand microphones that are more rugged and capable of being operated dependably even under changing conditions and over many years. In addition all cables must operate with all microphones in a studio complex and plug into any microphone outlet available. This presupposes use of a uniform powering system.

Although outdoor pickups used to often be done with dynamic microphones recently top quality condenser microphones have taken over. These con-denser microphones operate highly reliably when used under field conditions and their operation is not degraded either by high relative humidity or temperature. The high temperatures in motion picture and television studios, when numerous spotlights are on, present no problem to studio condenser microphones.
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Post by Viv » Sat Jan 24, 2004 4:31 pm

Oh well still stuck at the office but I did find this,

http://www.peroxidepropulsion.com/article/17

Effectively this is the same type of problem we have here, scroll down to were he has a link "here" to an xcell spreadsheet solution.

It makes interesting reading as he has a chamber pressure only 10psi higher yet gets 1100 meters a second out of his nozzle.

Oops have to run to lunch now finnish this later

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Raymond G
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Post by Raymond G » Sat Jan 24, 2004 7:24 pm

The Gluey nozzle is a simple sonic nozzle with a .250 in diameter throat. A sonic nozzle means that it can only accelerate the gas to the LOCAL speed of sound (i.e. based on static temp at the exit). However there is a lot more pressure energy in the propane, and if a convergent-divergant nozzle is used, a much higher jet velocity will be achieved. I calc about 3000 ft/sec for the 225 psi, 1200F, gaseous propane available. Otherwise, as stated above, I calc only 1400 ft/sec. I never understood why Gluey used a sonic nozzle in his design as he surly must have been aware of convergent-divergent nozzles. In fact, most jet pumps (usually steam based) use just that. I always assumed that he knew from testing that his induction system worked better by allowing the sonic jet form the nozzle to free expand in the first stage induction tube.

Viv,
I calc 1400 fps for the sonic velocity of propane at 1200 F. I'm not sure how you got 2381 fps, but maybe you forgot the G term (32.17 in english system), or used stagnation temp instead of static temp?

Regards,
Raymond

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Post by Viv » Sun Jan 25, 2004 6:54 pm

Raymond G wrote:Viv,
I calc 1400 fps for the sonic velocity of propane at 1200 F. I'm not sure how you got 2381 fps, but maybe you forgot the G term (32.17 in english system), or used stagnation temp instead of static temp?

Regards,
Raymond
Well this is a bit worrying! my long hand maths is not up to yours so I used a java calc on the hyperphysics web site to get this, it uses metric units but converting back and forth seems ok. sos of 726ms at 649c

I must be missing some thing though:-( were am I going wrong?

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Post by Viv » Sun Jan 25, 2004 7:38 pm

Raymond G wrote:The Gluey nozzle is a simple sonic nozzle with a .250 in diameter throat. A sonic nozzle means that it can only accelerate the gas to the LOCAL speed of sound (i.e. based on static temp at the exit). However there is a lot more pressure energy in the propane, and if a convergent-divergant nozzle is used, a much higher jet velocity will be achieved. I calc about 3000 ft/sec for the 225 psi, 1200F, gaseous propane available. Otherwise, as stated above, I calc only 1400 ft/sec. I never understood why Gluey used a sonic nozzle in his design as he surly must have been aware of convergent-divergent nozzles. In fact, most jet pumps (usually steam based) use just that. I always assumed that he knew from testing that his induction system worked better by allowing the sonic jet form the nozzle to free expand in the first stage induction tube.

Regards,
Raymond
A simple sonic nozzle! you know I had a horrible feeling thats what it would be, but for the life of I cant figure why he would use it in stead of the DeLavel type, it would explain the low figures but again why did he use it.

Or is it that the high speed nozzle would have made the intake stack to long? after all the speed has to drop to very low levels in the difuser section before it enters the combustion chamber.

Logically you would want to see the best nozzle to get the most out of the compression energy in the gas stream so it may come down to the intended rotot blade location for this engine.

Raymond what sort of speed do you think that nozzle will produce if the engine was blade mounted and the supply pressure was up to 700psi

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Post by Viv » Sun Jan 25, 2004 8:50 pm

Raymond did you get a chance to look at that ejector rocket site spreadsheet?

His figures look pretty good, tha mass figures are higher but its the same kind of set up as the first stack section.

Maybe all it needs to get the figures that Luc is looking for (and us:-) is to take the pressure jet away from the helicopter rotor blade application, if the engine was redesigned for max thrust but with out the space or machanical constraint I wonder what gains could be had?

Viv

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Post by Raymond G » Mon Jan 26, 2004 2:54 am

Viv,

Unfortunately, it doesn't really matter what the supply pressure is if you are using a sonic nozzle; the gas will be accelerated to the speed of sound, and any excess pressure energy will just result in an increased plume density (and mass flow). So a supply of 700 psi and 1200F will still only give 1400 f/sec theoretical exhaust velocity from a sonic nozzle.

Raymond

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Post by Raymond G » Mon Jan 26, 2004 3:05 am

Luv, Viv,
I am concerned that there has been no verification to my inquiry about whether the supply propane is liquid or gas. I did see Viv's reply about 225 psi being above the propane's vapor pressure, but that is not exactly relevant. In any propane tank that is not COMPLETELY FULL, there will exist saturated vapor propane in the top portion of the tank. If the supply lines from the tank exit the top of the tank, then you will get saturated vapor propane (i.e. propane gas). If the line exits the bottom of the tank, you will get liquid.

Also, your plumbing may limit the available flow rate ( i.e. have flow restrictors, too long a line, too many elbows, high drag valves, adverse head, etc.) to below what the jet needs to develop full thrust. You really need to verify that you are getting the flow rate from your supply that the engine needs.

Regards,
Raymond

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130R Power failure / Iowa State study on G8-2-130R / etc...

Post by Dave » Mon Jan 26, 2004 4:18 am

Guys

Three things:

Thing 1: Since we are talking about a device that is sonically tuned what are the side effects of trying to push a stream of fuel and possibly air through it faster than the speed of sound?

Thing 2: Some time ago I was able to get my hands on a copy of a study done at Iowa University, Aerospace and Engineering: "Analytical and Experimental Study of the Performance Characteristics of the Gluahar-eff G8-2-130R Engine" by Rory Eisele and Jesse Hilton. The study was performed in 2001 and ,among other things, includes thrust and acoustical tests. The abstract is one page, but the entire report is almost 40. Incidentally their engine was reported to produce a maximum of 110lb of thrust and turned into a blow torch with no thrust at nozzle pressures of 150psi or above. Presumably this was because of excess fuel flow flooding the heat exchanger. For those interested I should be able to scan it and post / email as desired.

3. Viv, if you are still looking for drawings / dimensions of the nozzle I can scan that portion of my plans for you. Just let me know.

Dave

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