Fuel Spray Dynamic Characteristics of GDI High Pressure Injection System

In order to improve the fuel consumption and exhaust emission for gasoline engines,gasoline direct injection（GDI） system is spotlighted to solve these requirements.Thus,many researchers focus on the investigation of spray characteristics and the fuel formation of GDI injector.This paper presents a complete numerical and experimental characterization of transient gasoline spray from a high pressure injection system equipped with a modern single-hole electric controlled injector in a pressurized constant volume vessel.The numerical analysis is carried out in a one-dimensional model of fuel injection system which is developed in the AVL HYDSIM environment.The experimental analyses are implemented through a self-developed injection rate measurement device and spray evolution visualization system.The experimental results of injection rate and spray dynamics are taken to tune and validate the built model.The visualization system synchronize a high speed CMOS camera to obtain the spray structure,moreover,the captured images are taken to validate the injector needle lift process which is simulated in the model.The reliability of the built model is demonstrated by comparing the numerical results with the experimental data.The formed vortex structure at 0.8 ms is effectively disintegrated at 6.2 ms and the spray dynamics become rather chaotic.The fuel flow characteristics within injector nozzle extremely influence the subsequent spray evolution,and therefore this point should be reconsidered when building hybrid breakup GDI spray model.The spray tip speed reach the maximum at 1.18 ms regardless of the operation conditions and this is only determined by the injector itself.Furthermore,an empirical equation for the spray tip penetration is obtained and good agreement with the measured results is reached at a certain extent.This paper provides a methodology for the investigation of spray behavior and fuel distribution of GDI engine design.

Influence of Pre-injection Control Parameters on Main-injection Fuel Quantity for an Electronically Controlled Double-valve Fuel Injection System of Diesel Engine

A simulation model of an electronically controlled two solenoid valve fuel injection system for a diesel engine is established in the AMESim environment.The accuracy of the model is validated through comparison with experimental data.The influence of pre-injection control parameters on main-injection quantity under different control modes is analyzed.In the spill control valve mode,main-injection fuel quantity decreases gradually and then reaches a stable level because of the increase in multi-injection dwell time.In the needle control valve mode,main-injection fuel quantity increases with rising multi-injection dwell time;this effect becomes more obvious at high-speed revolutions and large main-injection pulse widths.Pre-injection pulse width has no obvious influence on main-injection quantity under the two control modes;the variation in main-injection quantity is in the range of 1 mm3.

STRUCTURE PARAMETERS DESIGN AND PERFORMANCE TEST OF FUEL INJECTION SYSTEM

Based on the numerical simulation analysis, structure parameters of the high pressure fuel pump and common rail as well as flow limiter are designed and the GD-1 high pressure common rail fuel injection system is self-developed. Fuel injection characteristics experiment is performed on the GD-1 system. And double-factor variance analysis is applied to investigate the influence of the rail pressure and injection pulse width on the consistency of fuel injection quantity, thus to test whether the design of structure parameters is sound accordingly. The results of experiment and test show that rail pressure and injection pulse width as well as their mutual-effect have no influence on the injection quantity consistency, which proves that the structure parameters design is successful and performance of GD-1 system is sound.

Mathematical Model for the Injector of a Common Rail Fuel-Injection System

The paper describes a Diesel fuel injection process. Computer simulation was carried out together with measurement of the Common Rail accumulator fuel-injection system. The computer simulation enables the observation of the phenomena from rail pressure, being the input data for injection parameters calculations, to the injection rate. By means of computer simulation, the pressure values in specific sections of the injection nozzle may be computed, the needle lift, injection rate, total injected fuel, time lag from injector current to first evidence of injection process and other time-lags between various phases of the injection process. The injection rate provides input data for spray computer simulation. Measurements of injection and combustion were carried out within a transparent research engine. This engine is a single-cylinder transparent engine based on the AUDI V6 engine, equipped with a Bosch Common Rail Injection System. The comparison between the computed and measured injection parameters showed good matching.

Experimental Study on Effects of Fuel Injection on Scramjet Combustor Performance

In order to investigate the effects of fuel injection distribution on the scrarnjet combustor performance, there are conducted three sets of test on a hydrocarbon fueled direct-connect scramjet test facility. The results of Test A, whose fuel injection is carried out with injectors located on the top-wall and the bottom-wall, show that the fuel injection with an appropriate close-front and centralized distribution would be of much help to optimize combustor performances. The results of Test B, whose fuel injection is performed at the optimal injection locations found in Test A, with a given equivalence ratio and different injection proportions for each injector, show that this injection mode is of little benefit to improve combustor performances. The results of Test C with a circumferential fuel injection distribution displaies the possibility of ameliorating combustor performance. By analyzing the effects of injection location parameters on combustor performances on the base of the data of Test C, it is clear that the injector location has strong coupled influences on combustor performances. In addition, an irmer-force synthesis specific impulse is used to reduce the errors caused by the disturbance of fuel supply and working state of air heater while assessing combustor performances.

Design of speed controller for electronic fuel injection gasoline generator based on feed-forward PID control

As for the application of electronic fuel injection （EFI） system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor accuracy, a feed-forward control strategy based on load combined with proportional-integral-differential （PID） control strategy was proposed, and a digital speed controller applied to the electrical control system was designed. The detailed control strategy of the controller was intro- duced. The hardware design for the controller and the key circuits of motor driving, current sampling and angular signal captu- ring were given, and software architecture was discussed. Combined with a gasoline generator set mounted with EFI system, the controller parameters were tuned and optimized empirically by hardware in loop and bench test methods. Test results show that the speed deviation of generator set is low and the control system is stable in steady state; In transient state the control system responses quickly, has high stability under mutation loads especially when suddenly apply and remove 100% load, the speed deviation is within 8% of reference speed and the transient time is less than 5 s, satisfying the ISO standard.

Measurement and analysis of cycle fuel injection quantity for electronic unit pump

The cycle fuel injection quantity is accurately measured for electronic unit pump （EUP） operating at high, middle and low speeds by using displacement method based on EFS instantaneous mono-injector qualifier. On the basis of the experi- mental data about fuel injection quantity and fuel pressure, the variation of inconsistency in fuel injection quantity of EUP and the influence factors in different operating conditions are concluded. The results show that the inconsistency is lowest in maximum torque condition, while on the start and maximum power conditions, it is higher.

The Characteristic Analysis of the Electromagnetic Valve in Opening and Closing Process for the Gas Injection System

In this paper, the mathematical model of solenoid valve in the fuel injection system of gas engine is built. Simulation software Matlab/Simulink are employed to analyze the impact which the voltage, number of the coil turns and air gap width may produce to the open and close characteristics of the solenoid valve. The ideal response characteristics are got through the calculation. An optimal scheme which satisfies the operation requirements is put forward. The driving voltage and maintaining voltage are set as 90 V and 21 V;number of the coil turns is 30 N;air gap is determined as 0.6 mm;the opening and closing time are respectively 0.98 ms and 0.8 ms. This paper can be used as a reference for the design of the solenoid valve.

Extracting the core indicators of pulverized coal for blast furnace injection based on principal component analysis

An updated approach to refining the core indicators of pulverized coal used for blast furnace injection based on principal component analysis is proposed in view of the disadvantages of the existing performance indicator system of pulverized coal used in blast furnaces. This presented method takes into account all the performance indicators of pulverized coal injection, including calorific value, igniting point, combustibility, reactivity, flowability, grindability, etc. Four core indicators of pulverized coal injection are selected and studied by using principal component analysis, namely, comprehensive combustibility, comprehensive reactivity, comprehensive flowability, and comprehensive grindability. The newly established core index system is not only beneficial to narrowing down current evaluation indices but also effective to avoid previous overlapping problems among indicators by mutually independent index design. Furthermore, a comprehensive property indicator is introduced on the basis of the four core indicators, and the injection properties of pulverized coal can be overall evaluated.

An investigation of the performance of an electronic in-line pump system for diesel engines

WIT Electronic Fuel System Co.,Ltd.has developed a new fuel injector,the Electronic In-line Pump(EIP) system,designed to meet China's diesel engine emission and fuel economy regulations.It can be used on marine diesel engines and commercial vehicle engines through different EIP systems.A numerical model of the EIP system was built in the AMESim environment for the purpose of creating a design tool for engine application and system optimization.The model was used to predict key injection characteristics under different operating conditions,such as injection pressure,injection rate,and injection duration.To validate these predictions,experimental tests were conducted under the conditions that were modeled.The results were quite encouraging and in agreement with model predictions.Additional experiments were conducted to study the injection characteristics of the EIP system.These results show that injection pressure and injection quantity are insensitive to injection timing variations,this is due to the design of the constant velocity cam profile.Finally,injection quantity and pressure vs.pulse width at different cam speeds are presented,an important injection characteristic for EIP system calibration.

Effects of wall wetting and in-cylinder fuel distribution in an advanced turbo-charged engine

One of the proposed concepts for spark ignition engines is advanced port fuel injection(APFI),which suggests using two port injectors for each cylinder.In this research,we numerically examine the capabilities of this concept in reducing fuel consumption and increasing engine performance.The results demonstrated that the use of this concept is very effective due to the use of two injectors and the possibility of reducing the spraying time and bringing the injection start time closer to the air inlet valve opening time.The maximum amount of fuel film formed on the walls is reduced by about 75%,naturally,which leads to better and more homogeneous fuel distribution inside the combustion chamber and increases combustion efficiency.The results showed that under the same boundary conditions and engine operating point,the use of two port injectors for each cylinder leads to an increase of more than 20%of the maximum combustion chamber pressure and about 4%combustion efficiency.On the other hand,fuel film formation becomes worse in cold conditions.So in this study,the capabilities of this concept in cold conditions were investigated too.Investigations have shown that the advanced port fuel injection,unlike conventional engines,is almost insensitive to inlet temperature changes.

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.

Design of Rail Pressure Tracking Controller for Novel Fuel Injection System

This paper proposes a rail pressure tracking controller based on a novel common rail system. A mathematical model, based on physical equations, is developed and used for feed forward control design. Rail pressure peak sampling mechanism is designed to remove the disturbance of rail pressure due to fuel injection. All enhanced tracking differentiator is designed to get smooth tracking signal and exact differential signal from signal with noise. Double loop control strategy is designed to decouple the system and to improve dynamic performance of the system. Experimental results indicate that fluctuation of rail pressure is within il MPa in steady condition, while within ±3 MPa in transient condition, which verifies the effectiveness of the proposed rail pressure control strategy.

Two-phase Flow of Liquid-gas in Diesel Fuel Injection System and Their Effect on Engine Performances

In this paper, by using high-speed camera, CCD camera, signal and graph acquisition system, and other experimental instruments, investigation on liquid-gas two-phase flow in diesel fuel injection system and their effect on engine performances were made. Emerging and bursting of cavitation in the cavity above pump delivery valve, in injection pipe, and in fuel trough of injector of the fuel injection system were observed and mechanism of cavitation were discussed. Effects of liquid-gas two-phase flow on propagation velocity of pressure wave of the system and on irregular injection were analyzed. Two types of cavitation, long Living time cavitation and short living time cavitation, in the cavity above pump delivery valve of diesel fuel injection system were observed.

Application of the Computer Simulation Technique to Developing EFI Engine

The application of computer simulation technique to electronic controlled fuel injection(EFI) engine was studied to increase the development speed and improve the overall performance of the engine and car. On the basis of an EFI system developed by ourselves, the simulation model of the initial control data and engine operation points during a driving cycle and the car performance pridiction model were established. This method was applied to a mini car. The experiment showed that the simulated control data has good accuracy; and the engine test points and car performances obtained by simulation are useful for the matching of EFI system with gasoline engine and the development speed is increased.

Trajectory Analysis of Fuel Injection into Supersonic Cross Flow Based on Schlieren Method

Trajectory analysis of fuel injection into supersonic cross flow is studied in this paper. A directly-connected wind tunnel is constructed to provide stable supersonic freestream. Based on the test rig, the schlieren system is established to reveal the fuel injection process visually. Subsequently, the method of quantitative schlieren is adopted to obtain data of both fuel/air interface and bow shock with the aid of Photoshop and Origin. Finally, the mechanism based on two influential factors of fuel injection angle and fuel injection driven pressure, is researched by vector analysis. A dimensionless model is deduced and analyzed. The curve fitting result is achieved. The relationship between the data and the two influential factors is established. The results provide not only the quantitative characteristics of the fuel injection in supersonic cross flow but also the valuable reference for the future computational simulation.

A Review of Engine Fuel Injection Studies Using Synchrotron Radiation X-ray Imaging

Fuel spray characteristics directly determine the formation pattern and quality of the fuel/air mixture in an engine,and thus affect the combustion process.For this reason,the improvement and optimization of fuel injection systems is crucial to the development of engine technologies.The fuel jet breakup and atomization process is a complex liquid-gas two-phase turbulent flow system that has not yet been fully elucidated.Owing to the limitations of standard optical measurement techniques,the spray breakup mechanism and its interaction with the nozzle internal flow are still unclear.However,in recent years synchrotron radiation(SR)X-ray imaging technologies have been widely applied in engine fuel injection studies because of the higher energy and brilliance of third-generation SR light sources.This review provides a brief introduction to the development of SR technology and compares the critical parameters of the primary third-generation SR light sources available worldwide.The basic principles and applications of various X-ray imaging technologies with regard to nozzle internal structure measurements,visualization of in-nozzle flow characteristics and quantitative analyses of near-field spray transient dynamics are examined in detail.

Characterization and life prediction of single-pass honing tool for fuel injection nozzle

Single-pass honing is an important machining method for finish machining of holes,which can meet the requirement for high efficiency and consistency of holes.Characterization and life prediction of single-pass honing tool are necessary to improve the machining accuracy of holes honed,especially dimension accuracy.Single-pass honing tool is a single layer abrasive tool with fixed dimension,which still remains problematic for characterization and life prediction.For fuel injection nozzles with bore diameter under 1 mm,the stiffness of the single-pass honing tool is poor.This article presents a novel analytical model that predicts life of the tool with poor stiffness.Firstly,according to the bore diameter and dimension tolerance,the single-pass honing tool is designed and manufactured.Based on the prepared single-pass honing tool,the measurement and characterization methods are established.Furthermore,the tool wear tests are carried out,and the tool contour evolution model is established to predict the tool life.

Influence of fuel injection position and equivalent mixture ratio on chemical non-equilibrium effects of single expansion ramp nozzle

Chemical non-equilibrium flow was investigated for the scramjet single expansion ramp nozzle(SERN)with a strut-based liquid-kerosene-fueled combustor.Two-dimensional Reynolds-averaged NavierStokes(RANS)equations were solved with the species conservation equation for continuous phase and the renormalization group(RNG)k-εturbulence model.Lagrangian discrete-phase model was analyzed for liquidkerosene droplets behavior in the supersonic stream.Combustion was simulated by kerosene surrogate fuel's10-species and 13-step reduced reaction kinetics mechanism with use of Arrhenius's laminar finite rate model.Parametric studies were carried out to estimate the influence of different fuel injection positions and equivalent mixture ratios on the SERN chemical non-equilibrium effects.Numerical calculation results show that the strutbased combustor enables convenient modeling of various SERN entry conditions,which is similar with many preceding investigations,by changing the injector strut position and controlling the mass flow rate of each injector.Chemical non-equilibrium effects function in the whole SERN,especially in the initial flow expansion region,leads to obviously higher SERN performance of the non-equilibrium flow than that of the frozen flow.Furthermore,the distributed fuel injection pattern plays a significant role in enhancing the combustion efficiency in combustor,but weakening the chemical non-equilibrium effects funciton in SERN.Additionally,while the equivalent mixture ratio increases,the SERN thrust coefficient and lift coefficient rise gradually,and the increment of non-equilibrium flow in relation to frozen flow becomes higher as well.To be specific,the equivalent mixture ratio is 0.6,the maximum increment of thrust coefficient and lift coefficient are 11.6% and 25% respectively.

Effects of Ambient Conditions and Nozzle Design on the Velocity of Clustered Diesel Jets

The measurement of droplet velocities in Diesel sprays close to the nozzle is important because of the complexity of in-nozzle flow, spray break-up and evaporation. However, the measurement of droplet velocities in the dense region of Diesel sprays is very difficult or impossible by means of widely used laser diagnostic techniques, in particular under engine-like high-pressure and high-temperature conditions. The limitations of phase Doppler anemometry （PDA） and particle image velocimetry （PIV） prevent the application to the ultra-dense region of the spray. It was demonstrated that these problems can be greatly reduced by the laser flow tagging （LFT） technique. It was also demonstrated recently that LFT measurements can be conducted in clustered Diesel jets with improved spatial resolution and increased number of simultaneous measurements in the near-nozzle region. In the present work, the nozzle design, the temperature and pressure of the ambient air, and the fuel rail pressure are varied, in order to investigate the influence on the near-nozzle jet velocity and the underlying physical mechanisms.