Experimental Investigation of Dynamics Effects on Multiple-Injection Common Rail System Performance

Author(s):  
A. E. Catania ◽  
A. Ferrari ◽  
M. Manno ◽  
E. Spessa

Fundamental aspects of Common Rail (C.R.) fuel-injection system dynamics were investigated, paying specific attention to the wave propagation induced pressure oscillations and to their relationships with the system control parameters and multiple-injection performance. A detailed experimental analysis of the pressure wave propagation phenomena in a last-generation C.R Multijet equipment of the solenoid type was carried out on a high performance new test bench Moehwald-Bosch MEP2000-CA4000 under real engine simulated conditions. The experimental results include pressure time-histories in the rail and at the injector inlet, as well as flow-rate patterns, for both single and multiple injection events. The measured volume of fuel injected on each injection pulse is also reported. The analysis of the system oscillating behavior was carried out with the support of a simple lumped parameter model. Such a model was shown to be capable of predicting the main frequencies of the hydraulic circuit and their dependence on the geometrical parameters. The good agreement between the outcome of this simple model and the experimental data also substantiated the reliable authors’ interpretation of the cause and effect main relations underlying the complex flow phenomena occurring in the system. A refined computational model was developed and validated in a parallel work ([9]), providing a hydrodynamic analysis tool complementary to experimentation and a means of hydraulic system layout design and optimization. Finally, the mutual fluid-dynamic interactions taking place between consecutive injection events by distinct injectors of the same system are investigated in addition to the difference in dynamics of VCO- and Minisac-nozzle injectors.

2021 ◽  
Vol 20 (5) ◽  
pp. 427-433
Author(s):  
G. M. Kuharonak ◽  
M. Klesso ◽  
A. Predko ◽  
D. Telyuk

The purpose of the work is to consider the organization of the working process of six-cylinder diesel engines with a power of 116 and 156 kW and exhaust gas recirculation. The following systems and components were used in the experimental configurations of the engine: Common Rail BOSСH accumulator fuel injection system with an injection pressure of 140 MPa, equipped with electro-hydraulic injectors with seven-hole nozzle and a 500 mm3 hydraulic flow; direct fuel injection system with MOTORPAL fuel pump with a maximum injection pressure of 100 MPa, equipped with MOTORPAL and AZPI five-hole nozzle injectors; two combustion chambers with volumes of 55 and 56 cm3 and bowl diameters of 55.0 and 67.5 mm, respectively; cylinder heads providing a 3.0–4.0 swirl ratio for Common Rail system, 3.5–4.5 for mechanical injection system. The recirculation rate was set by gas throttling before the turbine using a rotary valve of an original design. The tests have been conducted at characteristic points of the NRSC cycle: minimum idle speed 800 rpm, maximum torque speed 1600 rpm, rated power speed 2100 rpm. It has been established that it is possible to achieve the standards of emissions of harmful substances: on the 116 kW diesel engine using of direct-action fuel equipment and a semi-open combustion chamber; on the 156 kW diesel using Common Rail fuel supply system of the Low Cost type and an open combustion chamber.


Author(s):  
Gian Marco Bianchi ◽  
Piero Pelloni ◽  
Giovanni Osbat ◽  
Marco Parotto ◽  
Rita Di Gioia ◽  
...  

Upcoming Euro 4 and Euro 5 emission standards are increasing efforts on injection system developments in order to improve mixture quality and combustion efficiency. The target features of advanced injection system are related to their capability of operating multiple injection with a precise control of amount of fuel injected, low cycle-by-cycle variability and life drift, within flexible strategies. In order to accomplish this task, performance must be optimised since injection system concept development by acting on. The extensive use of numerical approach has been identified as a necessary integration to experiments in order to put on the market high quality injection system accomplishing strict engine control strategies. The modelling approach allows focusing the experimental campaign only on critical issues saving time and costs, furthermore it is possible to deeply understand inner phenomena that cannot be measured. The lump/ID model of the whole system built into the AMESim® code was presented in previous works: particular attention was devoted in the simulation of the electromagnetic circuits, actual fluid-dynamic forces acting on needle surfaces and discharge coefficients, evaluated by means 3D-CFD simulations. In order to assess new injection system dynamic response under multiple injection strategies reproducing actual engine operating conditions it is necessary to find to proper model settings. In this work the integration between the injector and the system model, which comprehends the pump, the pressure regulator, the rail and the connecting-pipes, will be presented. For reproducing the dynamic response of he whole system will be followed a step-by-step approach in order to prevent modelling inaccuracies. Firstly will be presented the linear analysis results performed in order to find injection system own natural frequencies. Secondly based on linear analysis results will be found proper injection system model settings for predicting dynamic response to external excitations, such as pump perturbations, pressure regulator dynamics and injection pulses. Thirdly experimental results in terms of instantaneous flow rate and integrated injected volume for different operating conditions will be presented in order to highlight the capability of the modelling methodology in addressing the new injection system design.


2018 ◽  
Vol 7 (4) ◽  
pp. 2594
Author(s):  
Razieh Pourdarbani ◽  
Ramin Aminfar

In this research, we tried to investigate all the fuel injection systems of diesel engines in order to select the most suitable fuel injection system for the OM357 diesel engine to achieve the highest efficiency, maximize output torque and reduce emissions and even reduce fuel consumption. The prevailing strategy for this study was to investigate the effect of injection pressure changes, injection timing and multi-stage injection. By comparing the engines equipped with common rail injection system, the proposed injector for engine OM357 is solenoid, due to the cost of this type of injector, MAP and controller (ECU). It is clear that this will not be possible only with the optimization of the injection system, and so other systems that influence engine performance such as the engine's respiratory system and combustion chamber shape, etc. should also be optimized. 


Author(s):  
O. Chiavola ◽  
F. Palmieri ◽  
G. Chiatti

A model for the analysis of diesel engine common rail injection system has been developed and the influence that different fuels have on the injection performances has been investigated. Diesel fuel, biodiesel and kerosene have been used and the differences of injection flow rate, injection pressure time trace, nozzle flow features and break up mechanism have been highlighted. The coupling of two different codes has been used in the simulations: the former one, AMESim code, has been adopted to model the common rail system and to investigate the fuel flow rate and the injection pressure dependence on the fuel type. The latter computational tool, FIRE code, has been initialized by means of the results obtained from the injection system simulation and has been used to perform the 3D investigation of the internal nozzle flow and of the spray formation phenomena, aimed at evaluating the effect of physical fuel features on local flow characteristics and their influence on the system performances. Details of the adopted modeling strategy are described and results of each simulation step are presented.


2013 ◽  
Vol 655-657 ◽  
pp. 486-490 ◽  
Author(s):  
Zi Lai Luo ◽  
Kang Huang

According to the characteristics and the future tendency of common rail systems for marine diesel engines,the paper used a new injector. A simulation model of the common rail system with new injector was established using HYDSIM system, pressure fluctuation of the common rail pipe and pressure loss of the injector as evaluation indicator, the injector was simulated and optimized using DOE method. Simulation results show that appropriate selection of the structure parameters of the injector structure can effectively prevent the injectors from interfering each other and degree pressure loss of injector.


2001 ◽  
Author(s):  
M. Borghi ◽  
M. Milani ◽  
M. Piraccini

Abstract The paper is aimed at studying the overall dynamic behavior of the Common Rail Injection System actually used on a 4 cylinder industrial Diesel engine. Firstly, the paper introduces the main characteristics of a lumped and distributed parameters model of the high pressure branch of an actual Common Rail System, and the main hypotheses assumed to model it using a multi-port approach code for the analysis of the dynamic response of hydraulic systems submitted to fast transients. The model of the Common Rail System is then used to study its dynamic behavior when involved in the handling of the engine injection cycle for medium values of the crankshaft regime and for different pressure levels in the Rail. The analysis is performed applying to the injectors, to the pressure control valve and to the high-pressure pump the control strategies imposed by the Electronic Central Unit (ECU), as actually implemented into an industrial ECU for Diesel engine management. The model reliability and accuracy are evidenced through a numerical vs. experimental data comparison, mainly in term of rail pressure dynamic behavior. The analysis successively outlined in the paper allows to state how the hydraulic behavior of the Common Rail System interact with the electro-hydraulic injectors dynamics, and to determine the influence of this interaction on the total injected mass per cycle.


Author(s):  
Andrea Emilio Catania ◽  
Alessandro Ferrari ◽  
Michele Manno

A rather complete mathematical model for a Common Rail injection-system dynamics numerical simulation was developed to support experimentation, layout and control design, as well as performance optimization. The thermo-fluid dynamics of the hydraulic system components, including rail, connecting pipes and injectors was modeled in conjunction with the solenoid-circuit electromagnetics and the mechanics of mobile elements. Onedimensional flow equations in conservation form were used to simulate wave propagation phenomena throughout the high-pressure connecting pipes, including the feeding pipe of the injector nozzle. In order to simulate the temperature variations due to the fuel compressibility, the energy equation was used in addition to mass conservation and momentum balance equations. Besides, the possible cavitation phenomena effects on the mass flow rate through the injector bleed orifice and the nozzle holes were taken into account. A simple model of the electromagnetic driving circuit was used to predict the temporal distribution of the force acting on the pilot-valve anchor. It was based on the experimental time-histories of the current through the solenoid and of the associated voltage that is provided by the electronic control unit (ECU) to the solenoid valve. The numerical code was validated through the comparison of the prediction results with experimental data, that is, pressure, injected flow rate and needle lift time-histories, taken on a high performance test bench Moehwald-Bosch MEP2000-CA4000. The novel injection-system mathematical model was applied to the analysis of transient flows through the hydraulic circuit of a commercial multijet second-generation Common Rail system, paying specific attention to the wave propagation phenomena, to their dependence on solenoid energizing time and rail pressure, as well as to their effects on system performance. An insight was also given into the model capability of accurately predicting the wave dynamics effects on the rate and mass of fuel injected when the dwell time between two consecutive injections is varied.


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