Accurate measurement of the dynamic flow characteristics of injector nozzles is essential for evaluating fuel injection performance and optimizing combustion efficiency in modern engines. However, due to the ultra-short injection duration, high injection pressure, and strong transient flow behavior, the high-precision measurement of injector nozzle dynamic flow remains a significant technical challenge. In this study, a high-precision measurement method for the dynamic flow characteristics of injector nozzles is proposed, and systematic error analysis is conducted to improve measurement accuracy and reliability.
A high-response fuel flow measurement system is developed based on a combination of high-frequency pressure sensors, precision flow meters, and high-speed data acquisition modules. The real-time dynamic flow rate is obtained through transient pressure signal reconstruction and numerical integration. Meanwhile, a high-speed solenoid-driven injector test bench is built to simulate actual operating conditions under different rail pressures and injection pulse widths. The dynamic injection flow curves are measured under various working conditions, including different injection frequencies, fuel temperatures, and back pressures.
To ensure the accuracy of the measurement results, major error sources such as sensor response delay, sampling frequency limitation, signal noise, fuel compressibility, and temperature fluctuation are comprehensively analyzed. An error compensation model is established through system calibration and data filtering algorithms. Experimental results show that the proposed method can effectively capture the transient flow variation during the whole injection process, with a measurement accuracy better than ±2.5%. The repeatability error is controlled within 2%, indicating good system stability and reliability.
The proposed high-precision dynamic flow measurement method provides an effective technical means for injector performance evaluation, spray optimization, and injection strategy calibration. It also offers valuable experimental support for the development of high-efficiency and low-emission fuel injection systems.
Keywords: Injector nozzle; Dynamic flow measurement; High precision; Error analysis; Injection performance
Technical Route / Methodology
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Test System Design and Construction
A high-precision injector dynamic flow test system is designed, which mainly consists of a high-pressure fuel supply unit, injector driving and control module, precision flow measurement module, high-frequency pressure sensor, and high-speed data acquisition system. The system is capable of simulating real engine injection conditions with rail pressure up to 200 MPa and injection frequency above 100 Hz. -
Dynamic Flow Measurement Principle
The instantaneous flow rate of the injector nozzle is obtained by coupling transient pressure signal measurement with flow reconstruction algorithms. Based on the continuity equation and fuel compressibility characteristics, the dynamic flow rate is calculated through numerical differentiation and integration of pressure signals in a calibrated measuring chamber. -
Signal Acquisition and Processing
High-speed data acquisition hardware with a sampling frequency above 100 kHz is employed to capture transient pressure and control signals. Digital filtering, baseline drift correction, and noise suppression algorithms are applied to improve signal quality and ensure accurate dynamic flow curve reconstruction. -
Experimental Scheme and Operating Conditions
Dynamic flow tests are conducted under different rail pressures, injection pulse widths, fuel temperatures, and back pressures. Repeated experiments are performed to evaluate the repeatability and stability of the measurement system. -
Error Source Identification and Analysis
The main sources of measurement error, including sensor dynamic response error, sampling delay, fuel temperature variation, mechanical vibration, and signal noise, are analyzed both theoretically and experimentally. -
Error Compensation and Calibration
System calibration is carried out using a standard flow source. An error compensation model is established through regression analysis and temperature-pressure correction. The effectiveness of the compensation method is verified by comparative experiments. -
Result Evaluation and Validation
The accuracy, repeatability, and dynamic response performance of the measurement method are quantitatively evaluated. The measured dynamic flow results are compared with reference methods to validate the proposed approach.
