Page:Performance of a high-speed compression-ignition engine using multiple orifice fuel injection nozzles.djvu/4

N.A.C.A. Technical Note No. 344 The two general means of effecting this mixture are the motion of the fuel and the motion of the air, and both are effective to a certain extent in every combustion chamber. The degree of utilization of these motions varies from the combustion chamber depending almost entirely on air flow to that which has such a low rate of air flow that the motion of the fuel is but slightly different from that in quiescent air of the same density.

The use of air flow usually entails a loss in mechanical efficiency as well as an additional heat loss to the coolant and at the present time not enough is known about persistent air flow during injection to utilize this means to its best advantage. Since the induced air flow changes its velocity with engine speed, it can be utilized over only a limited range of speeds.

Therefore, it seemed desirable to investigate the possibility of obtaining the requisite mixture of fuel and air by injecting the fuel through a combination of round orifices in a nozzle, so that it would be properly distributed throughout the air in a combustion chamber. It is impossible to eliminate air flow entirely, but in the combustion chamber used in this investigation the rate appears to be so low that there is no evidence of its influencing the distribution of the fuel.

Both Ricardo (Reference 1) and Hesselamn (Reference 2) have used multiple orifice, nozzles and have published results