Would the two stroke spark ignition PV digram be same as for a 4 stroke?

  • Engineering
  • Thread starter lee123456789
  • Start date
  • #1
Poster has been reminded to show more effort in their schoolwork posts
Homework Statement:
write about engines
Relevant Equations:
none
Would two stroke spark ignition PV digram be same as 4 stroke spark ignition. both have otto pv diagrams.

1623567900237.png
 

Answers and Replies

  • #3
What research have you done on this so far?
ive write about everything just getting confused on the PV diagrams pics to put into the document. i think its otto pv diagram.
 
  • #5
How many strokes can you identify on the diagram in the OP?
I was thinking on the diagram
stages 1 -2 - 3 compression and 3 -4 - 1 was expansion
 
  • #6
jack action
Science Advisor
Insights Author
Gold Member
2,208
3,784
A stroke is a displacement ##V_s##. From 2 to 3 and 4 to 5, there are no displacements (constant volume), so let's forget about those for the moment. But you are correct with 1-2 for compression and 3-4 for expansion. But what about 0-1 and 5-0?
 
  • #7
A stroke is a displacement ##V_s##. From 2 to 3 and 4 to 5, there are no displacements (constant volume), so let's forget about those for the moment. But you are correct with 1-2 for compression and 3-4 for expansion. But what about 0-1 and 5-0?
would 2 -3 be ignition phase and 4 - 5 would heat rejection?

0 - 1 Intake Stroke?
5 - 0 Exhaust Stroke?
 
  • #8
jack action
Science Advisor
Insights Author
Gold Member
2,208
3,784
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.
0 - 1 Intake Stroke?
5 - 0 Exhaust Stroke?
So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
 
  • #9
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.

So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
There would just be a compression stroke and expansion stroke and the exhaust would be in included in the compression stroke and intake would be included in compression stroke?
 
  • #10
There would just be a compression stroke and expansion stroke and the exhaust would be in included in the compression stroke and intake would be included in compression stroke?
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.

So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
I think this would be the sequence of 2 stroke

0 to 1 intake phase
1 to 2 compression stroke
2 to 3 ignition phase
3 to 4 expansion stroke
4 to 5 heat rejection phase
5 to 0 exhaust phase
 
  • #11
jack action
Science Advisor
Insights Author
Gold Member
2,208
3,784
Post #9 is good, post #10 is wrong, or at least confusing. The intake phase (0-1) and exhaust phase (5-0) will not appear on the PV diagram as they will be included in the compression and expansion strokes. They are only 2 strokes.
 
  • #12
Post #9 is good, post #10 is wrong, or at least confusing. The intake phase (0-1) and exhaust phase (5-0) will not appear on the PV diagram as they will be included in the compression and expansion strokes. They are only 2 strokes.
I think this is it

0 to 1 to 2 to 3 compression stroke - included intake phase, compression stroke and ignition phase.

3 to 4 to 5 to 0 power stroke - includes power stroke, heat rejection, and exhaust phase
 
  • #13
jack action
Science Advisor
Insights Author
Gold Member
2,208
3,784
There are no 0 to 1 nor 5 to 0 lines drawn on the PV diagram. That is the difference between the 2-stroke and the 4-stroke PV diagrams. The 2-stroke has only 4 points:

-assignment-help-with-two-stroke-engine-pv-diagram.jpg
Both the intake & exhaust phases will begin somewhere between 3 and 4 and end somewhere between 1 and 2.

Versus a 4-stroke engine PV diagram:

23ae3f3d-8f23-488a-b17e-f7f95ac1d435.jpg
 
  • #14
There are no 0 to 1 nor 5 to 0 lines drawn on the PV diagram. That is the difference between the 2-stroke and the 4-stroke PV diagrams. The 2-stroke has only 4 points:

Both the intake & exhaust phases will begin somewhere between 3 and 4 and end somewhere between 1 and 2.

Versus a 4-stroke engine PV diagram:

Sorry could u layout the strokes eg 1 to 2 to 3.
Sorry for being thick.


1 to 2 to 3 I take, compression stroke and ignition.

3 to 4 to 1. Power stroke, heat rejection and exhaust.
 
  • #15
jack action
Science Advisor
Insights Author
Gold Member
2,208
3,784
If you look at the 4-stroke engine PV diagram in my last post, a downward stroke is from TDC (top dead center) to BDC (bottom dead center) and an upward stroke is from BDC to TDC. The same limits applied to a 2-stroke engine.
 

Related Threads on Would the two stroke spark ignition PV digram be same as for a 4 stroke?

  • Last Post
Replies
4
Views
6K
Replies
1
Views
10K
Replies
1
Views
1K
Replies
2
Views
12K
Replies
1
Views
2K
Replies
2
Views
725
Replies
0
Views
3K
Top