I am trying to program a basic Otto engine cycle and am having difficulty with states 2-3. Between these states, I need to have a numerical method that calculates a new pressure based on the old pressure and relationships with known values and constants. The independent variable is crank angle (theta). I've attached a working copy of the worksheet as well as some notes depicting the logic.
I've attempted to use theta as both a vector index and range variable but haven't been successful. Thank you in advance.
Solved! Go to Solution.
Additionally, there was a term missing from the recommended edit, please see attached...
I hope this help you
Study 15. Otto Cycle or what is behind the simplified formula
Thank you for providing these references. From what I could tell, these are not directly applicable to the approach I am taking with a variable heat release rate at variable timing (spark initiation and duration). They are however a terrific source for future use.
Would fit these changes to the program?
but between P23 and P12 = U0 there is no difference as shown in the graph.
This looks promising... I'll try to implement and provide more feedback.
Looking further, and this is manageable with the previous routine, P_34_Theta takes the form of P_12_Theta but with a unique Kappa defined by the last state (Pressure and Volume) from 23. And the final angle/state (4) just drops back to P_i or atmospheric.
Thanks for the recommendation, more to follow.
Can you share how you declared V0? I'm not able to see that on what was furnished.
Additionally, there was a term missing from the recommended edit, please see attached...
Hi Joshua Keena,
I added a zero to the name all variables which may be confused with those of physical constants, or units of measure.
Hi F.M.
Thanks... I made the changes and I see what you mean about there not being a difference between the two vectors. It appears that the loop isn't overwriting the original pressures in that vector (P_23). Please see attached for v3. I've transposed both vectors (P_12 and P_23) for comparison at the end of the worksheet.
Sincerely,
Josh
So FM, fourth time's a charm!
See attached, based largely on you unlocking the numerical routine to get the process done for states 2-3, and finding an error in my index notation, I got it to work. At the bottom of the worksheet you'll see the classic 'P-V' diagram for an Otto cycle, and below it plotted on a log-log basis.
Thanks again for your assistance!
With gratitude,
Josh
So FM, fourth time's a charm!
See attached, based largely on you unlocking the numerical routine to get the process done for states 2-3, and finding an error in my index notation, I got it to work. At the bottom of the worksheet you'll see the classic 'P-V' diagram for an Otto cycle, and below it plotted on a log-log basis.
Thanks again for your assistance!
With gratitude,
Josh
Hi JK,
The result is wonderful.
Good continuation of your work!
Greetings
FM
FM,
Thanks, and thanks as well for your tips and support.
Sincerely,
Josh