ディーゼル機関用燃料噴射弁の流量特性

第2報ホールノズル噴孔部の飽和特性

抄録

This report describes flow characteristics of small orifices. The experiment was carried out using a 0.4 mm diameter orifice under injection pressures from 25 to 417 atg and under back pressures up to 50 atg.
The results are as follows:
(1) Flow coefficient is expressed as a function of Reynolds number in the range of E_t<E_tc, where E_t is Euler number and Etc is the critical Euler number.
(2) Relation between cavitation and flow conditions is:
a) Noncavitation region (E_t<E_tc) -laminar flow
b) Transitional region - mixed flow where cavitation initiates or disappears (E_t≅E_tc)
c) Cavitation development region (E_tc<E_t<200) -turbulent flow of low Reynolds number
d) Limited cavitation region (E_t≥200) -turbulent flow of high Reynolds number.
(3) Flow characteristics of small orifices were obtained plainly. Especially for E_t≥E_tc and E_t≥3, flow rate at small orifices is determined only by injection pressure and given by equation (17) .