Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 3rd January 2015, 20:19   #106
Distinguished - BHPian
 
Join Date: Oct 2012
Location: Delhi
Posts: 3,512
Thanked: 9,030 Times
Default

Quote:
Originally Posted by rev_rohit View Post
Does that mixture/lean control lever increase air intake or reduce fuel intake to make the mixture leaner?



It has to be increase in air intake rather than reducing the fuel intake.



Then the mixture/lean control is doing the same thing as that of a Turbocharger. Just controlled manually with a separate lever or with a microprocessor or microprocessor overridden by pilot's command.



Whatever it is, it has to be a Turbocharger may be with a fancy name which takes compressed air into the engine to make it burn the fuel completely to compensate for loss of power at high altitudes.

They are two completely different things. The Cirrus has a turbo charged engine and a lever to lean
Jeroen
Jeroen is online now   (1) Thanks Reply With Quote
Old 4th January 2015, 18:48   #107
BHPian
 
Join Date: Nov 2014
Location: New Delhi
Posts: 54
Thanked: 47 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Are these things arranged in series or in parallel configuration?
Does the air enter in Cirrus engine via single air intake valve or two separate valves, one for turbo and other for leaning device?
rev_rohit is offline   Reply With Quote
Old 5th January 2015, 05:05   #108
Distinguished - BHPian
 
Join Date: Oct 2012
Location: Delhi
Posts: 3,512
Thanked: 9,030 Times
Default

Quote:
Originally Posted by rev_rohit View Post
Are these things arranged in series or in parallel configuration?
Does the air enter in Cirrus engine via single air intake valve or two separate valves, one for turbo and other for leaning device?

I have no idea. i fly the thing, and thats difficult enough.
Jeroen
Jeroen is online now   (1) Thanks Reply With Quote
Old 5th January 2015, 07:33   #109
BHPian
 
Join Date: Nov 2014
Location: New Delhi
Posts: 54
Thanked: 47 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Thanks Jeroen!!
I really appreciate your in depth knowledge about engines and your efforts in answering all my stupid queries.
It would be highly appreciated if someone answers this query. Whether the leaning device on jet engine is a manual adjustment for air intake on the Turbocharger or not.
There is no doubt that with Turbochargers engines have become more efficient, lesser polluting and more versatile!!!
rev_rohit is offline   Reply With Quote
Old 5th January 2015, 12:14   #110
Senior - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,076
Thanked: 2,879 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by Aromal View Post
... You are saying turbo-charger in cars can so something Jet-engines can't ?? I find it amusing, since both of them are basically gas turbines.
Hmmm ... this is something new! Where does the injection system of a petrol or diesel turbine inject fuel into the Turbocharger? I thought it was driven by exhaust gases and nothing combusts inside the TC!
DerAlte is offline   Reply With Quote
Old 5th January 2015, 12:57   #111
Senior - BHPian
 
mallumowgli's Avatar
 
Join Date: Apr 2010
Location: Palakkad/Coimbatore
Posts: 1,133
Thanked: 760 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by DerAlte View Post
Hmmm ... this is something new! Where does the injection system of a petrol or diesel turbine inject fuel into the Turbocharger? I thought it was driven by exhaust gases and nothing combusts inside the TC!
Technically both are same - Gas + air is ignited in the combustion chamber/engine and the exhaust gas runs the turbine
mallumowgli is offline   Reply With Quote
Old 5th January 2015, 13:24   #112
Senior - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,076
Thanked: 2,879 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by mallumowgli View Post
Technically both are same - Gas + air is ignited in the combustion chamber/engine ...
Oh! I thought they weren't the same.

A Gas Turbine has the fuel injected and combust in the chamber containing the driving vanes (not the air compressor vanes chamber), producing the energy input converted to kinetic energy by the turbine impellers.

The TC has nothing injected into it, and impeller is moved by the exhaust gases forced over the vanes - potential energy of the engine exhaust pressure converted to kinetic energy of the impeller.

This is as much as the difference between a compressor with a motor attached to it (energy input), to an air motor like what one finds in a pneumatic tools - which converts the potential energy of the high-pressure compressed air to kinetic energy of the motor impeller.
DerAlte is offline   Reply With Quote
Old 5th January 2015, 13:37   #113
Senior - BHPian
 
mallumowgli's Avatar
 
Join Date: Apr 2010
Location: Palakkad/Coimbatore
Posts: 1,133
Thanked: 760 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by DerAlte View Post
Oh! I thought they weren't the same.

A Gas Turbine has the fuel injected and combust in the chamber containing the driving vanes (not the air compressor vanes chamber), producing the energy input converted to kinetic energy by the turbine impellers.
If the fuel is ignited in the chamber containing the vanes, what flows where to produce the force required to turn the turbines?
mallumowgli is offline   Reply With Quote
Old 5th January 2015, 13:43   #114
Senior - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,076
Thanked: 2,879 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by mallumowgli View Post
If the fuel is ignited in the chamber containing the vanes, what flows where to produce the force required to turn the turbines?
Sir, any relevant online physics / mechanical engineering text, or Wikipedia, should be able to tell you that. @Sutripta or @jeroen can give you pointers.
DerAlte is offline   Reply With Quote
Old 5th January 2015, 14:08   #115
Senior - BHPian
 
mallumowgli's Avatar
 
Join Date: Apr 2010
Location: Palakkad/Coimbatore
Posts: 1,133
Thanked: 760 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by DerAlte View Post
Sir, any relevant online physics / mechanical engineering text, or Wikipedia, should be able to tell you that. @Sutripta or @jeroen can give you pointers.
OK, here goes - from Wikipedia

http://en.wikipedia.org/wiki/Gas_turbine

Quote:
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between.

The basic operation of the gas turbine is similar to that of the steam power plant except that air is used instead of water. Fresh atmospheric air flows through a compressor that brings it to higher pressure. Energy is then added by spraying fuel into the air and igniting it so the combustion generates a high-temperature flow. This high-temperat ure high-pressure gas enters a turbine, where it expands down to the exhaust pressure, producing a shaft work output in the process. The turbine shaft work is used to drive the compressor and other devices such as an electric generator that may be coupled to the shaft.
The reason why I put that question is to say that the burnt gas has to flow and expand to produce the force. If it burns inside the turbine chamber itself means it will just burn around the vanes and then escape through any outlet without producing any change in the vanes
mallumowgli is offline   Reply With Quote
Old 5th January 2015, 16:42   #116
Distinguished - BHPian
 
Join Date: Oct 2012
Location: Delhi
Posts: 3,512
Thanked: 9,030 Times
Default Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by rev_rohit View Post
Thanks Jeroen!!
I really appreciate your in depth knowledge about engines and your efforts in answering all my stupid queries.
It would be highly appreciated if someone answers this query. Whether the leaning device on jet engine is a manual adjustment for air intake on the Turbocharger or not.
There is no doubt that with Turbochargers engines have become more efficient, lesser polluting and more versatile!!!

A couple of points. Could be semantics, Typically what we call jet engines do not have leaning or TCs for that matter. jet engines are gas turbines.
And no, the TC has not made engines more efficient. There is a thread on that somewhere on the forum. The main purpose of a TC is to get more horsepower out of the same lump of steel/iron.

There is a huge difference between a TC on your car or any engine for that matter and what we call a gas turbine and or sometimes a jet engine, as other members are trying to point out to you. Reread DerAlte post again, he is spot on.

Not to confuse the topic even more, but most commercial jet airliners are powered by so called by pass jet engines. The gas turbine amongst other thing s,also powers the huge blades at the front of the engines. Most of the air entering the engine is actually blown past (blow by) the combustion chambers. So in fact most of the thrust is developed by the air by passing the actual gas turbine so to speak. It is in essence like a normal propellor planes, but with a huge cowling around the spinning blades for better aerodynamic efficiency.


Jeroen

Last edited by Jeroen : 5th January 2015 at 16:48.
Jeroen is online now   (1) Thanks Reply With Quote
Old 5th January 2015, 16:52   #117
Senior - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,076
Thanked: 2,879 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by mallumowgli View Post
... The reason why I put that question is to say that the burnt gas has to flow and expand to produce the force. If it burns inside the turbine chamber itself means it will just burn around the vanes and then escape through any outlet without producing any change in the vanes
Hint: Please look at the shape of the vanes. They are not parallel lines (that would support your assumption).

Starting at the shaft, the gap between the vanes increases till the periphery - THAT is the expansion route. While expanding, the hot gases put pressure on the vane face, making the vanes and shaft turn, and ultimately anything connected to the shaft.

In a Gas Turbine, there is an air compressor on one side which compresses air feeding the combustion chamber, where fuel is ignited, which heats the air, which produces hot air, which expands and moves the vanes and the shaft, which drives the aforementioned air compressor and anything else connected to the shaft <huff, pant, huff, pant>. In a jet engine, the gases exiting the jet exhaust apply a force to the whole assembly which moves the aircraft forward. In a Turbo-Prop engine, the GT (it is not a jet engine) rotates the propeller.

In a vehicle TC, hot exhaust gases from the engine (there is no combustion chamber in the TC) are fed in near the shaft, and the expansion path turns the vanes and the TC shaft, which turns the compressor, which compresses the air, which is led to the intercooler, etc. etc.
DerAlte is offline   Reply With Quote
Old 5th January 2015, 21:00   #118
Newbie
 
Join Date: Dec 2014
Location: Alappuzha
Posts: 22
Thanked: 19 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by Jeroen View Post
Most of the air entering the engine is actually blown past (blow by) the combustion chambers. So in fact most of the thrust is developed by the air by passing the actual gas turbine so to speak. It is in essence like a normal propellor planes, but with a huge cowling around the spinning blades for better aerodynamic efficiency.
In that case How does Jet engine start? At least from what I know, there are no electric motors like cars in aeroplanes
How does the engine get initial air for starting? How is the fuel delivery timed? What about the working cycle & different stages of combustion?

Sorry for too many questions & I'm asking this to you since, I find you very comfortable to answer to queries of novice like me.
Aromal is offline   Reply With Quote
Old 5th January 2015, 21:49   #119
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Calcutta
Posts: 3,638
Thanked: 2,410 Times
Default Re: Engine size inversely proportional to Fuel efficiency?

Quote:
Originally Posted by DerAlte View Post
@Sutripta or @jeroen can give you pointers.
Me? I'll sit on the sidelines and learn!
Jeroen has the patience of Job in a teaching role. I'll leave it to him!

Regards
Sutripta
Sutripta is offline   Reply With Quote
Old 6th January 2015, 01:27   #120
Distinguished - BHPian
 
Join Date: Oct 2012
Location: Delhi
Posts: 3,512
Thanked: 9,030 Times
Default

Quote:
Originally Posted by Sutripta View Post
Me? I'll sit on the sidelines and learn!

Jeroen has the patience of Job in a teaching role. I'll leave it to him!



Regards

Sutripta

I'm sitting on a beautiful beach in the West Indies enjoying my holiday. I'm done teaching for the moment
Jeroen
Jeroen is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
What is your Actual Fuel Efficiency? normally_crazy The Indian Car Scene 5138 1st July 2018 18:03
Why the heck do we care ONLY about Fuel Efficiency GTO The Indian Car Scene 118 4th July 2012 15:00
Fuel efficiency of Chevy Aveo 1.4 narasimhan Technical Stuff 1 2nd May 2006 00:51
Swift ZXi Climate control_improve fuel efficiency pranil Technical Stuff 21 13th March 2006 18:16
honda city (new) (old) and mitsubishi lancer fuel efficiency devarshi84 The Indian Car Scene 3 19th July 2005 12:39


All times are GMT +5.5. The time now is 13:55.

Copyright 2000 - 2018, Team-BHP.com
Proudly powered by E2E Networks