Anyone know what this is???

[UnAnswerd]

I've heard of "turbo prop" which is a turbine engine spinning a propeller. I've heard of "turbo jet" which is your typical jet engine hanging off the wings of an airliner. But can anyone tell me what in the heck "turbo fan" is???

 

[qmaster3]

http://www.aircraftenginedesign.com/abe_right3.html

 

[UnAnswerd]

http://www.aircraftenginedesign.com/abe_right3.html

Hey thanks for the link. Pretty good pictures in there. I assume you can identify a turbofan by the distinctive turbine blades in front of the engine????

 

[qmaster3]

I assume it's turbofan (blades), and turboprops (props) Of course I am just the son of a GM/Ford tech.

Avbug will probably be here shortly to write a few pages.


Here's a better link

http://www.lerc.nasa.gov/WWW/K-12/airplane/turbfan.html

 

[Singlecoil]

Hey thanks for the link. Pretty good pictures in there. I assume you can identify a turbofan by the distinctive turbine blades in front of the engine????

You can also see them hanging off the wings of 737's, 757's, 767's, 747's, 777's, Airbus', etc.

 

[Gatorman]

The difference between the two can be difficult to see for some people. Putting it into simpler terms:
A turbo jet engine has a single shaft that connects the turbines with the fan blades.
A turbo fan engine has an additional shaft with a second set of turbine blades driving the forward set of inlet blades, i.e., the fan.

Did I make that simple enough?

 

[9GClub]

Bypass ratio is a crucial concept when you're distinguishing between turbojets and turbofans. The short answer is that a turbojet sends everything it sucks in through the engine core [i.e. through the compressor(s), burners, and turbine(s)]. A turbofan, on the other hand, sends some air around the engine core. Blowers on modern military jets typically have relatively low bypass ratios, whereas large commercial fans have higher bypass ratios. For example, the P&W F119 on the Raptor runs in the 0.25:1 range, which effectively makes it an almost-turbojet. The GE90-115B on the B772LR/773ER runs about 9:1. In the latter example, this means that for every unit of air going through the engine core, you've got nine units bypassing it. High-bypass fans are typically quieter and more fuel efficient than their low-bypass counterparts, but obviously each has pros and cons depending on the application.

As Gatorman noted, modern fans can get complex because they often incorporate multiple shafts, both high and low-pressure compressor/turbine stages, etc. Another topic you might wanna research is axial versus centrifugal-flow compressors. Engine technology has come a long way since the 1930s-- to the point where GE now has in the -115B a powerplant with a thrust-to-weight ratio of around 6:1. Who knows where aerospace engineering would be if cost- effectiveness wasn't a consideration.......

 

[Tina Fey's Scar]

Make the madness stop....

 

[USMCmech]

A turbo jet engine has a single shaft that connects the turbines with the fan blades.
A turbo fan engine has an additional shaft with a second set of turbine blades driving the forward set of inlet blades, i.e., the fan.

Useually, but not always.

By defintion a Trubofan allows air to bypass the "core" of the engine where the fuel is burned.

Most of the time turbofans are "dual spool" designs, but if they only ran off of one shaft it would still be a turbofan.

 

[avbug]

Bypass air is the key to deciding if it's a turbofan. Today, most all jet engines are turbofan engines. Turbofan engines have a bigger cross section than turbojet engines.

You can tell the two apart on takeoff. Turbofan engines sound pleasant, where turbojet engines make you hold your ears. Still a nice sound, but turbojets, generally speaking, sound a lot louder.

Turbojet powerplants become more efficient with altitude; higher up the turbojet thrust is the breadwinner. Turbofan powerplants produce greater efficiency with the fan at lower altitudes, with the jet thrust doing it's thing higher up.

qmaster, do you really need several pages?