Server status
DCS version: 1.5.6, 2.0.5
SR version: 1.2.9.1/1.2.6.0
DCS OB same version as DCS Stable? Yes!
September 2017
MonTueWedThuFriSatSun
    123
45678910
11121314151617
18192021222324
252627282930 

Calendar Calendar

Latest topics
» FORUM BROADCAST FUNCTION
Today at 1:44 by (A/229) Comanchero86

» Good shot - wrong target
Thu 21 Sep 2017 - 0:02 by (D/229) Gizzy

» Previous applicant
Wed 20 Sep 2017 - 7:40 by (D/229) Flubber

» C-Tek Warthog Cyclic Extension
Tue 19 Sep 2017 - 23:37 by (B/229) ice_crusher

» Hey everyone we are flying more often!
Tue 19 Sep 2017 - 12:26 by (A/229) Huckleberry

» Sick Call Illness
Sat 16 Sep 2017 - 6:50 by (A/229) Huckleberry

» Mi-8/Mi-24 Cyclic and Collective setup
Fri 15 Sep 2017 - 22:25 by (B/229) Molevitch

» Hey everyone we are flying more often!
Wed 13 Sep 2017 - 8:37 by (D/229) Flubber

» Mi-8 Now has GPS on-board...
Wed 13 Sep 2017 - 0:59 by (A/229) Guinness


How a Jet engine works

Page 2 of 2 Previous  1, 2

View previous topic View next topic Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 9:07

Ok, like I said, it's been a while since I've had my theory on turbine engines, but I don't remember moving stator vanes as common. I thought most are fixed.

About your question... I don't really get it, it depends on angle of attack and speed, right? If a lift generating wing would be level, it would want to go upward because that's where the lower pressure is and that's where the higher pressure is pushing it. But what forces are you talking about?

So you mean that R1, R2, are in the N2 section?

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 10:29

Stator vanes dont rotate, hence stator = static. Rotor vanes rotate. Most, if not all stators can change pitch. Not sure if this applies to turbojet aircraft.

Stator vanes are mechanically linked to each other and the throttle, IIRC. The throttle pushes or pulls the mechanical links on the stator vanes that increase or decrease their pitch (angle of attack). R1, R2, R3 are turbine wheels in the hot section. N1, N2, N3...they are in the cold section of the engine. The R* section rotor wheels turn a shaft that is connected directly to the N1 fan. The rotors in the compressor section aft of N1 are free floating with regards to the stators in the compressor.

The hot section is where combustion takes place - ie fuel injectors/ignitors. This section is called the turbine. This is visible if you look inside the tailpipe.
The cold section is the compressor section, sits forward of the combustion chamber. N1 is the only part of the compressor that is clearly visible.


As for my above question, its in regards to what force keeps your aircraft airborne. Has nothing to do with AoA or speed. Well, it does, but only applies if your aircraft is actually configured to continue to fly. Its either low pressure above the aircraft sucking it up into the air, or the high pressure under the wing that pushes it up in the air. Ill go a step further. When you lose AoA and velocity, you will have low pressure under your aircraft, and high pressure above your aircraft. Which force is greater?

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 10:54

I never said stator vanes rotate... I have a feeling we´re talking past eachother all the time.. :)I think that fixed stators are more common. Being linked to throttle directly would cause compressor stalls I think. More likely it's linked to the N1 or something. If stators can be rotated, it's mostly the first stages, I do not think all. They can only adjust AoA to streamline airflow, I really don't think it's to increase velocity.

Like I said before, I've never heard of R1, R2, R3. I have the most feeling with turboshafts. I know for a fact that N2 is definitely not in the cold section, it's in the hot section. At least in the turboshaft I'm familiar with. But I assume it's with all turbines because it makes sense.

About the question:
The only force that keeps an aircraft airborne is lift, generally speaking ofcourse. First you say AoA and speed have nothing to do with keeping an aircraft airborne, then you say it does... You lost me..
A step further? Losing AoA and velocity... You say there's low pressure under the aircraft, high pressure above? I disagree. You'd have to explain that because it makes no sense to me.
Also, I ask again, what forces are you talking about? The only forces acting on an aircraft that I know of are lift, thrust, drag and weight... So without any AoA and speed, there won't be much lift, so the force of the weight will be stronger, to answer your question.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 11:11

N2 is a compressor blade, its definitely in the cold section.

A step further? Losing AoA and velocity... You say there's low pressure under the aircraft, high pressure above? I disagree. You'd have to explain that because it makes no sense to me.
Just a simple question, which force is greater on your aircraft? The low pressure or the high pressure? You are making the question a little too tricky on yourself. Leave AoA and velocity out of the question. Drag and thrust, lift and gravity. They create positive pressure under the airfoil, and create low pressure above the airfoil. Leave it at that.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 11:41

No, sorry, N2 is in the hot section, at least in this one:

And I still don't understand your question lol. What kind of forces are the low and high pressures exerting according to you?

You said without AoA and without speed, you get low pressure below, high pressure above the aircraft.
Without AoA and speed, you're falling down, so I'd say the lower pressure is above the aircraft, not below! Please explain.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 13:02

I guess different engineering companies, different labeling. By P&W standards, R1 is what you consider N2. N2 in this case, not only is in the cold section, but also drives the gear box. In lieu of R1 and R2, this diagram shows high pressure turbine and low pressure turbine.



Anyways, just pretend the aircraft is and will always be in flight. Stop making it difficult.
When an airfoil moves through the air, lift is generated. What is generating this lift? The low pressure above the wing, or the high pressure underneath the wing?

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 18:47

In your picture, could it be that n1 and n2 indicate shafts, instead of compressors?

I'm not making it difficult, I just look at things in a practical way, and you keep changing the question. Before this post you said there was no AoA and no speed, now I gotta imagine the plane flies forever...
But to answer the latest question: Both.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 22:45

In the picture, N1 and N2 are compressor blades. Only N1 is connected to the shaft. N1 is driven by the high pressure turbine wheel, which is connected to the shaft to N1. N1 rotates at a much lower velocity than the other compressor blades due to its disk diameter. N1 provides the mass airflow to both cool the case down and force cool, dense air around the compressor blades, which rotate freely on frictionless bearings along the shaft. This is different in torque producing engines.

I dont keep changing the question, you keep adding variables that dont need to be known. There are only 2 variables that need to be known, and thats the low pressure above the wing, and the high pressure below the wing. I asked this question because propellers and the vanes inside the turbines function exactly the same way.

Low pressure above the wing is the greater force. The aircraft is literally sucked into the air because low pressure = higher velocity. Higher pressure = lower velocity. Same thing with turbine engines and propellers: the aircraft is propelled forward because the air coming into the engine is considerably slower than the air exiting the tailpipe.  Those escaping exhaust gases are leaving at high velocity/low pressure, with high pressure being compressed even further in the compressor section.

In the case of turboshaft engines the exiting exhaust gases is redirected towards an impeller, which provide rotating force for the propellers. It is the propellers that push the aircraft forward (and rotor blades push the heli upwards), which in turn generate thrust in the form of low pressure above the rotor disk and in front of the propellers, and high pressure behind the propellers and below the rotor disk.  

IIRC, in helicopters, the greatest force providing lift is the high pressure underneath the disk, but this rule only applies to helicopters that are in ground effect.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Sun 18 Aug 2013 - 23:48

Aren't the N1 and N2 just indicators of the spools? That's what I've found in multiple posts online, and that's what makes the most sense, for any brand engine.

About the question again:
Those variables are mandatory. If there's no AoA, no speed, there would be no low and no high pressure zones around the wing. Also, if the AoA would be very high, at any given speed, the higher pressure hitting the bottom of the wing for instance would be far greater than the lower pressure on top of the wing.
It all depends on AoA and speed if you ask me.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Mon 19 Aug 2013 - 0:00

N1 and N2 are read by instruments, yes. They are also compressor stages.

Those variables are mandatory, yes. But you are still making this way too difficult, because if your aircraft is in flight, then they are already taken into account. Simple question turned into a thesis for some reason or another, so I shall refrain from asking any more questions that generate steam from the ears. If your aircraft is in flight, then the low pressure above the wing is greater than the high pressure on the bottom of the wing. Airflow above the airfoil is faster than the airflow on the bottom of the airfoil. Greater velocity, lower pressure. Its why you hear a vacuum sound when a jet does a tight turn.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by Guest on Mon 19 Aug 2013 - 7:34

I think about it too much I guess, but I did enjoy our little one-two here, got me to refresh my knowledge Smile

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by (HHC/229) GunfighterSIX on Sat 5 Oct 2013 - 4:06

Just remember when describing lift that "longer path theory" now longer applies.  This theory is being thrown out.



Last edited by (A/229) GunfighterSIX on Sat 5 Oct 2013 - 4:21; edited 1 time in total
avatar
(HHC/229) GunfighterSIX
Chief Warrant Officer 4
Battalion Standardization Instructor Pilot
Rated Master Aviator
Chief Warrant Officer 4  Battalion Standardization Instructor PilotRated Master Aviator

Messages : 750
Age : 35
Location : VA, USA

Back to top Go down

Re: How a Jet engine works

Post by (HHC/229) GunfighterSIX on Sat 5 Oct 2013 - 4:14

If you guys are trying to find more on jet engines, remember N1 is also known as NG or the gas producer part of your engine and N2 is NP or your power turbine.  depending on manufacture n1 & n2 are used or NP or NG.  that will help with your searches.

_________________
avatar
(HHC/229) GunfighterSIX
Chief Warrant Officer 4
Battalion Standardization Instructor Pilot
Rated Master Aviator
Chief Warrant Officer 4  Battalion Standardization Instructor PilotRated Master Aviator

Messages : 750
Age : 35
Location : VA, USA

Back to top Go down

Re: How a Jet engine works

Post by (A/229) Skeeter on Sat 5 Oct 2013 - 9:02

Let m redneck it. Air goes in the front side of the engine. That fuel ya put in is burnt and due to a expanding gas principal it rapidly expands and turns a doodad . That doodad turns the thing that thing is connected to a whatyamaycallit that turns the rotor. The expanded gas leaves the back of the engine and will burn ya.
lol @ Hitman. No really it is very interesting to see how it really works.

_________________
avatar
(A/229) Skeeter
Captain
Company Commander
Rated Senior Aviator
Captain Company Commander Rated Senior Aviator

Messages : 233
Age : 42
Location : Kosciusko, Mississippi

Back to top Go down

Re: How a Jet engine works

Post by (HHC/229) flyer on Sat 5 Oct 2013 - 9:07

Skeeter, I'm perty damn redneck and I see's your point...ceptin for that last part about the whatchamadigger.

_________________
Head Quarters Company, 229th Assault Helicopter Battalion, 1stCavDiv
Battalion S-1
avatar
(HHC/229) flyer
Major
S1
Instructor Pilot
Rated Master Aviator
Major S1 Instructor Pilot Rated Master Aviator

Messages : 1281
Age : 56
Location : Titusville, Florida

Back to top Go down

Re: How a Jet engine works

Post by Guest on Sat 5 Oct 2013 - 12:12

y'all are kinda late...this is like old school posting. August n stuff...

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by (A/229) Skeeter on Sat 5 Oct 2013 - 12:13

Yea it's the thingamajig that changes the engine to 90 degree output before the rotor.
Mississippi redneck here. Yep!

_________________
avatar
(A/229) Skeeter
Captain
Company Commander
Rated Senior Aviator
Captain Company Commander Rated Senior Aviator

Messages : 233
Age : 42
Location : Kosciusko, Mississippi

Back to top Go down

Re: How a Jet engine works

Post by Guest on Sat 5 Oct 2013 - 12:38

Is that farenheit or celsius?

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by (HHC/229) Strut on Sat 5 Oct 2013 - 14:04

Yor all missing the point, its the angle of the dangle, in direct proportion to the tilt of the kilt, with the measurement of the doodad in specific rotation of the correct aim to hit the top left pocket. Sinks the eight-ball every time...What a Face

_________________
avatar
(HHC/229) Strut
Major
Battalion XO
Rated Senior Aviator
Major Battalion XO Rated Senior Aviator

Messages : 1338
Location : Australia

Back to top Go down

Re: How a Jet engine works

Post by Guest on Sat 5 Oct 2013 - 14:11

that would fod out the doohickey.

Guest
Guest


Back to top Go down

Re: How a Jet engine works

Post by (A/229) Skeeter on Sun 6 Oct 2013 - 17:27

No that thingy on the left or right next to that there.

_________________
avatar
(A/229) Skeeter
Captain
Company Commander
Rated Senior Aviator
Captain Company Commander Rated Senior Aviator

Messages : 233
Age : 42
Location : Kosciusko, Mississippi

Back to top Go down

Re: How a Jet engine works

Post by Sponsored content


Sponsored content


Back to top Go down

Page 2 of 2 Previous  1, 2

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum