Aerodynamics: Optimization of an aircraft engine

[dd5139]

I am writing an essay about optimization of an aircraft engine. I have to show the derivation of aerodynamic drag eq. I need help about it because i couldn't find where it came from.

 

[Arjan82]

Hi there, welcome to the forum!

It is probably better to start a new topic on this next time instead of replying to an old thread (last post almost a year ago). We try to keep threads limited to the original topic.

But do you mean by 'the aerodynamic drag eq.' this one:
$$
F_d = \frac{1}{2}\rho u^2 A C_d
$$
If so then you ought to know that this is just the inverse of the definition of the drag coefficient ($C_d = \frac{2 F_d}{\rho u^2 A}$). The drag coefficient comes from dimensional analysis (The Buckingham $\pi$ Theorem). This drag coefficient is found to be similar for similarly shaped object. There are whole books written that give (a range of) $C_d$ values for differently shaped objects (most notably the historic 'Aerodynamic Drag' by Hoerner). But please note that $C_d$ is not always constant for even the same object in different flow conditions (like for different Reynolds numbers or different Mach numbers). Also, the million dollar question is how $C_d$ varies for small changes in the geometry.

 

[berkeman]

I am writing an essay about optimization of an aircraft engine. I have to show the derivation of aerodynamic drag eq. I need help about it because i couldn't find where it came from.

Welcome to PF.

Please show us your Google search terms that you have been using so far. This seems like a pretty easy search, so we would like to help you learn how to do searches like this better in the future.