IAE V2500 pressure loss

[Peyto193]

I am trying to find out the pressure loss for the IAE V2522-A5 turbofan and am having a lot of trouble. Does anyone have this information or know where I could find it?

 

[davidjh]

Do you mean the "as-installed inlet" pressure loss (ie from inlet front face back to engine blade front face), or some other value?

 

[rnordquest]

For the inlet pressure loss to the fan face you'll also have to specify the conditions: cruise, climb, 2nd segment climb, takeoff, idle descent, holding. Or you could specify airspeed, AOA, thrust level. If AOA <> 0 do you want average loss or max loss? Then there are transient conditions like wind up turns.

 

[Peyto193]

Well, I am trying to create a graph of trust available vs. speed. The equation I am using is
T(avl) = T(tst)[1-0.35K(t)M*[1-(pressure loss)]]-550(P(extr)/U)

where T(avl)=thrust available
T(tst) = Uninstalled Thrust (23000lb for the V2522)
K(t)= constant
M = flight mach number
P(extr) = Extracted Power
U = Velocity of flight

I am not sure how I go about finding the pressure loss. Thanks for all of the help you are trying to give me!

 

[davidjh]

The "uninstalled thrust" - 23000lbs - is a "benchmark" value that has no real usefullnes in determining the installed thrust at any flight condition. And the thrust at any flight condition cannot be determined from an equation as simple as the one shown. There are several "ratings" (Takoff, In-flight takeoff, MCL, MCT , MCR) each of which creates a certain (ie; different) thrust level at any given flight condition.

 

[davidjh]

The equation you define is also used in some airplane design courses where the uninstalled thrust for each of the above mentioned ratings is needed/used depending on the flight regime/condition being analyzed. It appears to be from Jan Roskam's design course book. Your term "pressure loss" is labeled "ninl" and is arbitrarly defined as 0.99 in the example I found. From examining the equation, 0.99 doesn't make sense as a "pressure loss", but it does make sense as an inlet pressure recovery factor, or as a total measure of correcting from uninstalled thrust to installed thrust (without accounting for power extraction). The Engine Type Certificate Data Sheets give the "official" uninstalled thrust values for "takeoff" and "MCT". I'm not sure where you go to get the values for 'Inflight takeoff", "MCL" nd "MCR" tho.

 

[Peyto193]

I am in my preliminary design course and was unable to access certain resources during the thanksgiving break, that equation is from Jan Roskam's text. You are correct about the inlet pressure recovery factor and I am consulting with my professor right now. Thank you very much for your help on this matter.

 

[rnordquest]

Wouldn't thrust available at constant altitude be relatively constant? Consider plane at near stall speed, flaps and gear up, then go to PLA max. The engine spools up to max thrust in under 7 sec. The plane accelerates to max speed but the thrust hasn't changed.

I consider thrust available to be max thrust available.

 

[davidjh]

mordquest;
I would say we need to think of two types of jet engines. The more recent designs have electronic control which keeps the engine at the appropriate (or selected) rating when the PLA is up in the "max power" portion of the quadrant. So as the airplane accelerates it will lower the engine fuel flow to keep it at the rating's power setting value (be it EPR or N1) for the airspeed. The older engines have the traditional "hydromechanical fuel control unit". The PLA angle to set/obtain rated thrust varies with many things (speed, temp, altitude). If the PLA is increased to to the rated thrust value when at the "near stall" speed and then left there while the airplane accelerates away from the stall, the engine will overboost beyond the thrust rating and into the realm where RPM redlines could be exceeded, and more likely where the internal pressure limits could be exceeded due to the great increase in inlet ram pressure.