Core gas temperature

The time from initiation of reaction (marked as the end of compression in Fig. 6.7) to the maximum rate of pressure rise in the first stage, which corresponds to the maximum in an accompanying light output, is defined as Ti. The interval from this point to the maximum rate of pressure rise in the second stage is defined as t2- When the variation of these parameters is plotted as a function of the isentropically compressed core gas temperature (see Section 6.3.5) it is found that ti decreases monotonically with increasing temperature, whereas t2 increases at first, before decreasing... 

In most, but not all circumstances, the core gas temperature, T, is the natural reference temperature for the compressed gas because the highest temperature at the end of compression is responsible for the development of spontaneous ignition in the shortest time [88, 95]. Exceptionally, when the compression heats the reactants to temperatures that correspond to the region of ntc for that particular mixture, combustion may be initiated in the cooler boundary layer region. That is, gases which, at the end of compression, are colder than those in the adiabatic core control the duration of the ignition delay. This was demonstrated by Schreiber and coworkers by the simulation of alkane combustion, using various reduced kinetic schemes, in computational fluid dynamic calculations [102-104]. 

The core gas temperature is derived from the measured pressure ratio. For a change Tj T2, produced by the small pressure change pi - p2,... 

If heat losses during compression are only slight then the bulk of the compressed gas will be at the core gas temperature. However, if heat losses during compression are very significant, as in slow compression, then a rather smaller fraction of the compressed charge will be at the core temperature. The extent to which heat losses during compression cause departures from the adiabatic ideal may be assessed from a comparison of (6.16) with the temperature (Tad) which is predicted on an ideal volumetric basis from knowledge of the dimensions of the RCM [50]. That is... 

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See also in sourсe #XX -- [ ]

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