Question

Redraw figure 4.9 using an x-axis scale of lambda (recipricol of equivalence ratio) and comment on the circumstances in which this graph would be a more appropriate form for presenting data.

Compression Ratio Knock Limit Turbulence: Normal High Rich Limit Weak Limit 0.5 2.5 1.5 2 Equivalence Ratio Figure 4.9 Effect of turbulence on increasing the engine operating envelope of SI engines - plotted against equivalence ratio.

Answer 1

Q. Given Solution - Compression Ratio - knock! limit Turbule Normal Weak Limit high 0.5 1 1.5 2 25 3 Equivalence Ratio 9) Figure shows the effect of the non- dimensional fuel air ratio on engine opera- lion. It is thus most relevent to full throttle operation, in which the ceir flow Tate will be approximately constant and the fuelling level is being raried Scanned with CamScanner

ssion ratio, b) Figure shows that at a high Compre- on ratio , then control with weak mixtures more difficult than control with rich mixtures Ratio - Turbulence Normal Compression - Limit iWeal · Limit 03 081.3 1.8 lambda -- Fig. (Effect of teu bulence on increasing the engine operating envelope of spark ignition engines), but plotted against Lambda 9) In con's trast, when the same data are plotted here aqounst lambda, a non- dimensional air fuel ratio, then this is ca espannedervitative of part throttle operation CamScanner

b) At part throttle the fuelling level will be almost fixed, and the air flow rate will be varied to give the maximum economy or power output , since the fuelling level is fixed c) The plot against lambda shows that at part load operation there is a Comparatively wide operating envelope at high compression ratios d) The differences is in the plots is a Consequences of taking reciprocals of numbers either side of unity. as Scanned with CamScanner
Conclusion- The first is plotted against Equivalence ratio vs Compression ratio

And the second graph is plottwd against the Lambda against Compression ratio.

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