Regulation characteristics of ultra-high-pressure injectors for wide-range fuel delivery

Abstract

Wide-range fuel delivery is essential for stable combustion and precise control, yet conventional injectors suffer from low resolution and strong nonlinearity at small injection quantities. This study investigates a high-linearity injector through combined experiments and multi-physics simulation to clarify full-range fuel delivery behavior and governing mechanisms. Injection-rate measurements and a validated dynamic model reveal a nonlinear injection quantity–pulse width ( Q–PW ) response at small pulse widths and a near-linear relationship after a stable high-flow stage is established. A segmented model is therefore developed for full-range fuel delivery prediction, and the critical pulse width ( PW c ) is identified as the macroscopic boundary between the two response regions. Mechanism analysis shows that the nozzle orifice diameter dominates the wide-range delivery capability, needle lift governs linear-region response and accuracy, and inlet/outlet orifice sizes jointly determine dynamic response. Larger nozzle and outlet orifices, increased needle lift, and a smaller inlet orifice expand the high-quantity regulation range, whereas opposite trends improve small-quantity control. A larger outlet throttling orifice ( DZ ), supplemented by an appropriately sized inlet orifice (DA ), provides the optimal basis for wide-condition adaptability. Comprehensive evaluation further indicates that structural parameters affect linearity, dynamic response, and modulation range in different ways, highlighting the importance of coordinated parameter matching. This work provides a basis for full-range fuel delivery prediction, structural optimization, and precision control of advanced high-pressure injection systems.