Luc and Viv
The realm of DeLavel nozzle design and CFD programs is over my head. My only suggestions at this point are:
1. If one new nozzle is good, might two be better? One smaller than the existing nozzle and one larger. (Actually, I was thinking larger.)
2. Although I do not have the FFT software that Viv has, I may be able to help you on the recording side. Do your best to avoid clipping when recording. Any decent sound editor (I have a few) should show you the recorded waveform. The volume levels generated by the engine can easily overdrive the input circuit and / or the microphone resulting in square (flat topped) wave forms. What you should see are wave forms with sharp or rounded peaks. Simply adjusting the input volume on the laptop may not be enough, an input pad between the microphone and the laptop may also be necessary to reduce clipping.
Luc in your earlier messages it appeared that you ready to give up, but your last message sounded much more positive. I too wish we lived closer. Best of luck with your next round of tests.
Dave
PS: How far are you from Buffalo NY?
Gluhareff 130R power failure issue still open ... Any Idear?
Moderator: Mike Everman
130R Power failure
Hi Dave,
First, I live close to Montreal and I think we are 5 to 6 hours apart.
As for a smaller nozzle, that could probably change thing but not bigger. Bigger would probably mean less speed, wich is not desirable.
As for quiting, It is not that I am ready to quite, but if we come to a dead end, of coarse I will stop fighting with it. Remeber, I am paid to do what I am doing now and I am not cheap. I use this forum as an exchange with you guys. I put ressources, manufacturing and testing capabilities available for you, so you can be involve in what we feel is the best path, in exchange for your brain and for all of use to complet, accomplish and benefit from a better engine. Time minute I will see that we are to a dead end, wich I beleive we are getting closer and closer ... That it, I will pull the plug.
Go look at the forum general page, this forum is probably the most read forum and I beleive that 100 guys read and follows what we are doing. Maybe a few of them have the answers or maybe not ... But one thing is sure ... I wont be able to put another $100,000.00 is this baby.
If someone know why this thing is not pushing 130 ... Speak and speak loud ... Greed and secrets as never hepled the sciense in going forward.
regards,
Luc
First, I live close to Montreal and I think we are 5 to 6 hours apart.
As for a smaller nozzle, that could probably change thing but not bigger. Bigger would probably mean less speed, wich is not desirable.
As for quiting, It is not that I am ready to quite, but if we come to a dead end, of coarse I will stop fighting with it. Remeber, I am paid to do what I am doing now and I am not cheap. I use this forum as an exchange with you guys. I put ressources, manufacturing and testing capabilities available for you, so you can be involve in what we feel is the best path, in exchange for your brain and for all of use to complet, accomplish and benefit from a better engine. Time minute I will see that we are to a dead end, wich I beleive we are getting closer and closer ... That it, I will pull the plug.
Go look at the forum general page, this forum is probably the most read forum and I beleive that 100 guys read and follows what we are doing. Maybe a few of them have the answers or maybe not ... But one thing is sure ... I wont be able to put another $100,000.00 is this baby.
If someone know why this thing is not pushing 130 ... Speak and speak loud ... Greed and secrets as never hepled the sciense in going forward.
regards,
Luc
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Luc, I know its hard to do any thing near the nozzle and the top of the first stack element, but have you ever mesured the depression at that point caused by the supersonic flow from the nozzle?
Viv
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130R Power failure
Viv,
To your last question. For us, it is impossible to do.
The only way we could acheive that, is running the engine in a CFD program. Wich I will probably do....soon.
Regards,
Luc
To your last question. For us, it is impossible to do.
The only way we could acheive that, is running the engine in a CFD program. Wich I will probably do....soon.
Regards,
Luc
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Re: 130R Power failure
Ok i was just wondering as it may be lower than we assume and throw the nozzle calc way off.Luc wrote:Viv,
To your last question. For us, it is impossible to do.
The only way we could acheive that, is running the engine in a CFD program. Wich I will probably do....soon.
Regards,
Luc
I am thinking about the rest but yes would love to see this beast in the test cell, I will try and get Graham to give a bit of advice about the recording as he is a profesional sound recording engineer, and also another member of the Albion team over here in the UK.
The CFD sounds the way to go, can it manage the acoustics as well? in particular the way the second and third harmonics mess up on the third full wave?
Viv
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130R power failure
Nope Viv,
Our CFD program is a thermodynamic and fluid mechanic software that will only consider, gas velocity, temperature, pressure, flow and others.
It will not consider the accoustique or the combustion process. That why it is useless to run the entire engine. I will just run the tree stages to have speed, pressure, temperature and flow figures.
Past stage 3, we fall in to the combustion process and it is useless to do that.
Cya,
Luc
Our CFD program is a thermodynamic and fluid mechanic software that will only consider, gas velocity, temperature, pressure, flow and others.
It will not consider the accoustique or the combustion process. That why it is useless to run the entire engine. I will just run the tree stages to have speed, pressure, temperature and flow figures.
Past stage 3, we fall in to the combustion process and it is useless to do that.
Cya,
Luc
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well if the available pressure to work with is going to be a maximum of 225psi the rest of the engine will just have to be optimized to get as much energy out of every single one of those psi as possible!
Stack one and two are for low level air entrainment and a small pressure gain, I would assume this should be kept to a low value so their is enough speed left in the stream to realize the maximum pressure gain in the last section witch is the diffuser and the final air mixing to bring the mixture up to 14/1.
Your CFD program should be a wiz at that:-)
Next is the acoustics, this can be tuned in real time with an audio fft program, as its not a pulse jet this should be a lot less complicated we have been used too:-).
The only sample I could find to run a FFT on was a G8-2-20, that showed up the problem with destructive addition of some of the harmonics, this is the cause of all the references to "stopping pulsation", fishtailing the end of the exhaust pipe and also drilling the small hole in the diffuser section, there are other ways to do this that may yield better results and so stabilize the position of the flame front and get higher compression.
Viv
Stack one and two are for low level air entrainment and a small pressure gain, I would assume this should be kept to a low value so their is enough speed left in the stream to realize the maximum pressure gain in the last section witch is the diffuser and the final air mixing to bring the mixture up to 14/1.
Your CFD program should be a wiz at that:-)
Next is the acoustics, this can be tuned in real time with an audio fft program, as its not a pulse jet this should be a lot less complicated we have been used too:-).
The only sample I could find to run a FFT on was a G8-2-20, that showed up the problem with destructive addition of some of the harmonics, this is the cause of all the references to "stopping pulsation", fishtailing the end of the exhaust pipe and also drilling the small hole in the diffuser section, there are other ways to do this that may yield better results and so stabilize the position of the flame front and get higher compression.
Viv
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130R power failure
Okey guys,
I have started the CFD programs for the Nozzle, intake stack and engine.
First, I have started with the full assembly (Nozzle, intake stack and engine) but the program took 41 minutes just to complete the meshing. So I have decided to run this in 3 steps.
Step 1. Will be the nozzle it self, to find gas velocity, using propane at 225 psi. at 1200°F.
Step 2. Will be the intake stack, using the Nozzle results.
Step 3. Will be the intake stack connected to the engine, as it represent a restriction for the intake stack performance.
Each time I complete a simulation, I will post the result and the flow image so you guys will have a nice fun evaluating these results.
I guess you guys are all exited and are ancious to see the first one ... He he he. Am I not a nice guy??? ... Lol.
Remember, I saw simulations that took 63 hours, once, so be patient, they will come.
Nice day guys,
Cya
Luc
I have started the CFD programs for the Nozzle, intake stack and engine.
First, I have started with the full assembly (Nozzle, intake stack and engine) but the program took 41 minutes just to complete the meshing. So I have decided to run this in 3 steps.
Step 1. Will be the nozzle it self, to find gas velocity, using propane at 225 psi. at 1200°F.
Step 2. Will be the intake stack, using the Nozzle results.
Step 3. Will be the intake stack connected to the engine, as it represent a restriction for the intake stack performance.
Each time I complete a simulation, I will post the result and the flow image so you guys will have a nice fun evaluating these results.
I guess you guys are all exited and are ancious to see the first one ... He he he. Am I not a nice guy??? ... Lol.
Remember, I saw simulations that took 63 hours, once, so be patient, they will come.
Nice day guys,
Cya
Luc
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Re: 130R power failure
Ok then we will all setle down and wait:-) the first one I want to see is what the differance is in the presant nozzle and the new one.Luc wrote:Okey guys,
I have started the CFD programs for the Nozzle, intake stack and engine.
First, I have started with the full assembly (Nozzle, intake stack and engine) but the program took 41 minutes just to complete the meshing. So I have decided to run this in 3 steps.
Step 1. Will be the nozzle it self, to find gas velocity, using propane at 225 psi. at 1200°F.
Step 2. Will be the intake stack, using the Nozzle results.
Step 3. Will be the intake stack connected to the engine, as it represent a restriction for the intake stack performance.
Each time I complete a simulation, I will post the result and the flow image so you guys will have a nice fun evaluating these results.
I guess you guys are all exited and are ancious to see the first one ... He he he. Am I not a nice guy??? ... Lol.
Remember, I saw simulations that took 63 hours, once, so be patient, they will come.
Nice day guys,
Cya
Luc
Viv
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Raymond G
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Hello All,
I just joined this group because I just found it. I have been interested in these things for years, though I have never really trusted the SFC figures for the 130 sized engine. Like others, I have performed my own performance calcs, and usually come up with a SPC in the 3-7 range, depending upon the initial assumptions. Any how, I have some input for Luc that may or may not be helpful. Please bear in mind that I have scanned all the posts on this topic, but did not read them in depth, so I may have missed an important point somewhere.
Thrust is the product of mass flow rate and exhaust velocity(mdot x V). Therefore, you need to verify that both are as they should be. With a thermocouple and a pressure gage (better 2 pressure gages to get both static and stagnation pressure) you can get both from the exhaust plume. I know this sounds basic, but can be anything but. The plans state that the airflow mdot is sensitive to both inlet and outlet sonic tuning, and also states that fuel flow mdot is sensitive to wether it is a LIQUIDor a VAPOR.
If you are using facilities style propane, as opposed to an actual bottle located near the engine, I would question wether you are getting LIQUID propane delivered to your engine. The plans specifically state that a substantial drop in thrust will result from using gaseous propane. The model turbine guys are well aware of this issue because they start their engines with LIQUID propane from an inverted cannister (they won't start if the cannister is right way up) I'm kind of going out on a limb saying this because I will of course seem foolish if this is a non-issue. But the plans do show a modified propane tank specifically designed to deliver liquid, not gaseous propane.
For sonic tuning, you should have adjustable length inlet and outlet ducts, to ensure this is not the issue. After all, it can take a single error in Gluhareff's plans to throw you off if you are duplicating his plans exactly. i.e. you should use the plans as a starting point.
The plans and manual I have seen suggest that 130 lbf thrust is not unreasonable for the 130. First, the thrust numbers roughly scale across the models. Secondly there is the Space Ranger VTOL pictured in the manual. Now I don't have enough experience to claim that this thing was real or not, but if it was, then there is no way it ever got off the ground on anything less than the claimed 130 lbf class.
This post has already gone on too long, so I will call it quits for now, and wait to hear some replies.
Regards,
Raymond
I just joined this group because I just found it. I have been interested in these things for years, though I have never really trusted the SFC figures for the 130 sized engine. Like others, I have performed my own performance calcs, and usually come up with a SPC in the 3-7 range, depending upon the initial assumptions. Any how, I have some input for Luc that may or may not be helpful. Please bear in mind that I have scanned all the posts on this topic, but did not read them in depth, so I may have missed an important point somewhere.
Thrust is the product of mass flow rate and exhaust velocity(mdot x V). Therefore, you need to verify that both are as they should be. With a thermocouple and a pressure gage (better 2 pressure gages to get both static and stagnation pressure) you can get both from the exhaust plume. I know this sounds basic, but can be anything but. The plans state that the airflow mdot is sensitive to both inlet and outlet sonic tuning, and also states that fuel flow mdot is sensitive to wether it is a LIQUIDor a VAPOR.
If you are using facilities style propane, as opposed to an actual bottle located near the engine, I would question wether you are getting LIQUID propane delivered to your engine. The plans specifically state that a substantial drop in thrust will result from using gaseous propane. The model turbine guys are well aware of this issue because they start their engines with LIQUID propane from an inverted cannister (they won't start if the cannister is right way up) I'm kind of going out on a limb saying this because I will of course seem foolish if this is a non-issue. But the plans do show a modified propane tank specifically designed to deliver liquid, not gaseous propane.
For sonic tuning, you should have adjustable length inlet and outlet ducts, to ensure this is not the issue. After all, it can take a single error in Gluhareff's plans to throw you off if you are duplicating his plans exactly. i.e. you should use the plans as a starting point.
The plans and manual I have seen suggest that 130 lbf thrust is not unreasonable for the 130. First, the thrust numbers roughly scale across the models. Secondly there is the Space Ranger VTOL pictured in the manual. Now I don't have enough experience to claim that this thing was real or not, but if it was, then there is no way it ever got off the ground on anything less than the claimed 130 lbf class.
This post has already gone on too long, so I will call it quits for now, and wait to hear some replies.
Regards,
Raymond
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Nice to meet you Raymond and welcome to the forum, don't worry about long posts you haven't met Larry yet:-)
Good points on the thrust calculations, Luc has experience of load cells and engine test stands so he has already confirmed the thrust measurements, this was covered near the beginning of the thread.
Air flow in the inlet stacks, Luc is running a CFD program for this at the moment and we are waiting for the results, but the main thing at the moment is to prove the nozzle is providing enough gas at the correct speed and is not just choking.
Acoustic tuning is an unknown but I would prefer to do that after the inlet stacks and nozzle have been verified by the CFD.
Another good suggestion regarding the liquid propane supply but in this case it is being pumped at 225psi so it is way above the vapor point, even at the end of the test stands long supply line it should still be liquid, but perhaps Luc could confirm that? maybe the line should be purged before a test run just to be sure.
The different mass flow rates of the restrictor valve at the heat exchanger coil inlet when passing liquid or gaseous propane would severely impact the thrust so it should be ruled out as a possible cause.
Viv
Good points on the thrust calculations, Luc has experience of load cells and engine test stands so he has already confirmed the thrust measurements, this was covered near the beginning of the thread.
Air flow in the inlet stacks, Luc is running a CFD program for this at the moment and we are waiting for the results, but the main thing at the moment is to prove the nozzle is providing enough gas at the correct speed and is not just choking.
Acoustic tuning is an unknown but I would prefer to do that after the inlet stacks and nozzle have been verified by the CFD.
Another good suggestion regarding the liquid propane supply but in this case it is being pumped at 225psi so it is way above the vapor point, even at the end of the test stands long supply line it should still be liquid, but perhaps Luc could confirm that? maybe the line should be purged before a test run just to be sure.
The different mass flow rates of the restrictor valve at the heat exchanger coil inlet when passing liquid or gaseous propane would severely impact the thrust so it should be ruled out as a possible cause.
Viv
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Recording High amplitude sound.
Hi.
Viv asked me if I could give you some suggestions/recommendations for making good recordings of your jet. I've not been following your argument so am not sure if you still need this information.
For the BCVP recordings which produce sound peaks in excess of 120dB @1m, the brief was to produce recordings that had the minimum of distortion and good reproduction of transient events - high slew rates and all that.
In order to achieve a good balance of the direct sound with the reverberant sound field, or even suppress the reverberant field, the microphone has to be quite close to the motor, and the motor a reasonable distance from reflective surfaces. This proximity forces us to consider heat and possible very high transient sound pressure levels.
The Omni directional pressure transducer was chosen for its excellent transient response, flat frequency response, lack of proximity effect and insusceptibility to popping. A microphone sensitivity is 8mV/Pa is good for this type of work, you would not want any more sensitivity. The types of microphone considered also must have a very high Maximum SPL; 154dB or higher are good.
The microphone amplifier not only has to supply 48V phantom power to the microphone but must offer a range of accurate gain settings from Unity up. With all the sparks and stuff it's important to have balanced lines throughout - from mic to micamp then micamp to recorder.
I'll do some more later.
Have a look at this.
http://www.earthwks.com/
http://www.dpamicrophones.com/
The earthworks mic amps are good.
Graham.
Viv asked me if I could give you some suggestions/recommendations for making good recordings of your jet. I've not been following your argument so am not sure if you still need this information.
For the BCVP recordings which produce sound peaks in excess of 120dB @1m, the brief was to produce recordings that had the minimum of distortion and good reproduction of transient events - high slew rates and all that.
In order to achieve a good balance of the direct sound with the reverberant sound field, or even suppress the reverberant field, the microphone has to be quite close to the motor, and the motor a reasonable distance from reflective surfaces. This proximity forces us to consider heat and possible very high transient sound pressure levels.
The Omni directional pressure transducer was chosen for its excellent transient response, flat frequency response, lack of proximity effect and insusceptibility to popping. A microphone sensitivity is 8mV/Pa is good for this type of work, you would not want any more sensitivity. The types of microphone considered also must have a very high Maximum SPL; 154dB or higher are good.
The microphone amplifier not only has to supply 48V phantom power to the microphone but must offer a range of accurate gain settings from Unity up. With all the sparks and stuff it's important to have balanced lines throughout - from mic to micamp then micamp to recorder.
I'll do some more later.
Have a look at this.
http://www.earthwks.com/
http://www.dpamicrophones.com/
The earthworks mic amps are good.
Graham.
130R Power Failure
Okey Guys,
The Nozzle simulation is done, but for some reason I can't post it on this forum. It is a 900K word document with image. So, I will send a copy to Viv, since I have his Email and Viv, see if you can attached the repport to a new post message so all of the guys can benefit from it.
Also, thanks Graham for your inputs. But, to be honest, what you expained sound more like Chinees to me. So I will do the recording with a laptop and it's internal microphone and you guys do the rest. Like I said before, I provide the resources and you guys provide the brain... He he he.
Cya
Luc ....Out
The Nozzle simulation is done, but for some reason I can't post it on this forum. It is a 900K word document with image. So, I will send a copy to Viv, since I have his Email and Viv, see if you can attached the repport to a new post message so all of the guys can benefit from it.
Also, thanks Graham for your inputs. But, to be honest, what you expained sound more like Chinees to me. So I will do the recording with a laptop and it's internal microphone and you guys do the rest. Like I said before, I provide the resources and you guys provide the brain... He he he.
Cya
Luc ....Out
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CFD report for nozzle
Dear all
Attached is the first test report from Luc's CFD run on the propane nozzle.
Viv
Attached is the first test report from Luc's CFD run on the propane nozzle.
Viv
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