﻿102 Messrs. H. T. Tizard and D. R. Pye 



the 



The results for plate A 5 were similar, the mean being 

 a = 0*53. In th© calculations the figure 0*51 has been 

 taken. 



Table V. 

 Ignition of mixtures of heptane and air. Fan full speed. 



Initial pressure = 14*86 lb./sq. in. Strength of mixture as 

 before. Mean apparent value of 7 = 1*310. 



No. of 



Corupn. 



Initial 



Max. Compn. 



Max. Aver. 



Delay obs. 



Cooling 



expt. 



ratio. 



temp. 



pressure. 



temp. calc. 



factors. 



B x •• 



6-03 



61° C. 



157*5 



310° C. 



16 sec. 





B .. 



552 



59 



139 



291 



No ignition. 



143 



B, .. 



5-73 



59'5 



148 



298 



}J 



1-40 



B 4 .. 



591 



59-5 



154 



304 



55 



1-36 



B 5 .. 



6-13 



59-5 



161 



310 



}J 



T47 



B G .. 



633 



595 



165 



313 



0-13 



— 



b: .. 



6-56 



59 



175 



321 



0-08 



— 



B 8 .. 



701 



60 



188 



336 



005 



— 



B 9 .. 



8-02 



60 



9 



362 



o-oo* 



— 



Mean= T42. 



* Ignited before top of compression. 



X. Considering firstly the results of the experiments 

 without the fan running, we find that at the lowest ignition 

 temperature of about 280° C, the temperature of the walls 



/HP A\ 



was about 40° C. The expression a ^— ^ (equation 11) 



T, 



has therefore the value — 



0*51 x 240 

 553 



0*22. 



Assume that the true ignition temperature under these 



conditions is 280° C. = 553 absolute, and that ^ -10: 



lo 

 then by integration of the theoretical equation (see Table II.) 

 we obtain the folio wing results : — 



