PPRuNe Forums - View Single Post - Altitude, Mixture and Fuel Flow
View Single Post
Old 27th Oct 2008, 13:50
  #9 (permalink)  
Dick Whittingham
 
Join Date: Oct 2000
Location: Bristol
Posts: 461
Likes: 0
Received 0 Likes on 0 Posts
OK, so we have to consider all sorts of variables. It is possible, however, to ask if for one engine at fixed RPM or MP a reasonable answer can be deduced Let's try and do that.

Specifically, answer me this: Consider an Otto cycle engine with all valve events at TDC or BDC. On the inlet stroke it inducts one cylinder's worth of volume. On the compression and power strokes nothing goes in or out. On the exhaust stroke one cylinder's worth of volume is expelled. Is the engine not passing one cylinder's worth of volume in each complete cycle? Does that not mean that at constant RPM volume flow is also constant?

And, skiingman, don't confuse mass flow with volume flow.

Dick

I'll come clean. Here is one of the doubtful questions I am trying to analyse to see if we should ask for it to be pulled or not

As altitude increases, if the mixture is not leaned:

A the volume of air entering the carburettor remains constant and the fuel flow decreases
B the volume of air entering the carburettor decreases and the fuel flow decreases
C both the density of air entering the carburettor and the fuel flow decrease
D the volume of air entering the carburettor decreases and the fuel flow increases

Last edited by Dick Whittingham; 27th Oct 2008 at 14:07.
Dick Whittingham is offline