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Post by hassanalawi on Mar 13, 2020 7:51:22 GMT -5
Hello Guys, hope every one good at nowadays world conditions I am building a turbojet engine as a senior graduation project, i ve been suffering earlier as i was following wrong information until i caught you people lol, i ve been reading all around the forum the past 2 weeks and its been really helpful and clear, but boy the amount of information scares me as i have to deliver this project within two months exactly. anyways, following the informations and guidance here i finally sketched a design for the flame tube as well as the combustion chamber. first thing first, i m using 40mm inducer Turbocharger and planing to use propane for startup then a mixture of liquid fuel (Kero/Diesel) according to jet specs parameters and also saw few recommendations regarding using liquid fuel which was to widen the size of the primary holes so i did this is the final draft, i would be grateful if you guys can verify it for me.
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Post by racket on Mar 13, 2020 17:41:55 GMT -5
Hi
If using a spray nozzle for liquid fuel then the Primary Zone holes need to be at the theoretical impact point of the spray on the flametube wall .
Also I'd be inclined to reduce your holes sizes a bit so as to increase the number to 8 or 10 at each zone .
Where is your slipjoint for axial flametube expansion??
Maybe extend the length of the rectangular section at the outlet of the flametube so that it can slip back and forth inside the mounting flange/scroll
Cheers John
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Chuks
Senior Member
Joined: August 2015
Posts: 498
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Post by Chuks on Mar 13, 2020 18:20:22 GMT -5
You are welcome to the forum. I guess You are a Nigerian?
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Post by hassanalawi on Mar 14, 2020 4:31:52 GMT -5
You are welcome to the forum. I guess You are a Nigerian? hello Chuks, no i am from Bahrain, tiny country in gcc
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Post by hassanalawi on Mar 14, 2020 5:21:57 GMT -5
Hi If using a spray nozzle for liquid fuel then the Primary Zone holes need to be at the theoretical impact point of the spray on the flametube wall . Also I'd be inclined to reduce your holes sizes a bit so as to increase the number to 8 or 10 at each zone . Where is your slipjoint for axial flametube expansion?? Maybe extend the length of the rectangular section at the outlet of the flametube so that it can slip back and forth inside the mounting flange/scroll Cheers John hello John, i m not sure about my fuel system arrangement yet but for sure i am going to use the simplest. For propane i am planing to use what you always recommend which is a small steel tubing with radial holes while for liquid fuel i quiet not settled however i m thinking of using a misting nozzle with hollow cone, 160 deg spray angle but not sure if i can find this locally and i dont know how much pressure i need to supply, if there is a simpler method it will be great so reduced the size in jet specs to have more holes but i m still confused as per how do i arrange these holes and what number of rows, previously i divided the flame tube into 3 sections and kept the rows either at center or equally spaced at each section, i dont know if there is a right method. Slipjoint: forgive me for the draft it is not clear but its there as you said and i will extend the flame tube further more
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Post by hassanalawi on Mar 14, 2020 9:43:03 GMT -5
mine will be vertical due to the turbocharger arrangement
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Post by hassanalawi on Mar 14, 2020 16:19:33 GMT -5
Also whats the range of value i ll be looking at for the: Boost pressure Combustion chamber pressure and temperature Oil pressure Oil temp Liquid fuel pressure Propane pressure Exhaust temp Rpm
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Post by racket on Mar 14, 2020 16:47:57 GMT -5
Just single row of holes at each Zone Slipjoint allows for different axial expansions between flametube and outer can whilst maintaining the air flow through the wall holes , it only needs to be a loose slipjoint with a millimeter clearance . This flametube jetandturbineowners.proboards.com/attachment/download/68 has an extended outlet "snout" which fits into the rectangular port in the combustor bottom plate for location, and can expand axially into the scroll to accomodate differential expansion , the flametube can expand several milimeters more than the outer can , so if fixed at the fuel injection end it needs to expand into the turb scroll . Yep , those parameters and a P4t pitot pickup downstream of the turbine wheel to measure total pressure exiting the wheel
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Post by hassanalawi on Mar 14, 2020 17:07:14 GMT -5
Just single row of holes at each Zone Slipjoint allows for different axial expansions between flametube and outer can whilst maintaining the air flow through the wall holes , it only needs to be a loose slipjoint with a millimeter clearance . This flametube jetandturbineowners.proboards.com/attachment/download/68 has an extended outlet "snout" which fits into the rectangular port in the combustor bottom plate for location, and can expand axially into the scroll to accomodate differential expansion , the flametube can expand several milimeters more than the outer can , so if fixed at the fuel injection end it needs to expand into the turb scroll . Yep , those parameters and a P4t pitot pickup downstream of the turbine wheel to measure total pressure exiting the wheel This picture describes it better, thankx John much appreciated What about the range of each of these parameters
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Post by racket on Mar 14, 2020 20:35:13 GMT -5
OK , suitable gauges ...........boost /P2 0-50 psi 0-3 Bar , combustor pressure should be roughly the same as P2 , temperature 0- 250 C for the compressed air temp , we don't measure gas temperatures going into the turbine, only exiting it for safety reasons as we don't want the thermocouple going through the turbine wheel if it fails. Oil pressure 0-100 psi 0-7 Bar Oil temp 0-200 C Liquid fuel pressure 0-100 psi - 0-7 Bar Propane pressure 0-100 psi - 0-7 Bar Exhaust temp ( TOT )/ Jetpipe temp 0-1,000 C K Type thermocouple Tach 0- 200,000 rpm for your size Your actual running parameters will be somewhere in those ranges , you might get ideas here jetandturbineowners.proboards.com/thread/680/diy-turbines , but there are a huge amount of variables to be taken into account for individual engines Your max boost/P2 will probably only need be ~22 psi - 1.5 Bar for safety reasons at ~170,000 rpm , T2 maybe 140 C , oil pressure 50 psi -3 bar and temp <100 C , fuel pressure whatever your pump is capable of , same with propane cylinder pressure , exhaust temp ~650 C max for safety
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Post by hassanalawi on Mar 15, 2020 0:17:57 GMT -5
Thankx john
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Post by hassanalawi on Mar 15, 2020 0:19:20 GMT -5
What do you guys recommend for a basic simple fuel system for the liquid fuel?
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Post by racket on Mar 15, 2020 2:40:26 GMT -5
Why do you want to use liquid fuel ??
A 40 mm inducered turbo will run OK on a 20lb-9kg BBQ cylinder of propane
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Post by hassanalawi on Mar 15, 2020 2:52:02 GMT -5
Why do you want to use liquid fuel ?? A 40 mm inducered turbo will run OK on a 20lb-9kg BBQ cylinder of propane Looking to produce thrust more than 10kgf
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Post by hassanalawi on Mar 15, 2020 3:20:24 GMT -5
Also proposed that in my proposal so i have to deliver this now
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