Linking the Physical Manifestation and Performance Effects of Injector Nozzle Deposits in Modern Diesel Engines

Continuous monitoring of diesel engine performance is critical for early detection of fault developments in an engine before they materialize into a functional failure. Instantaneous crank angular speed (IAS) analysis is one of a few nonintrusive condition monitoring techniques that can be utilized for such a task. Furthermore, the technique is more suitable for mass industry deployments than other non-intrusive methods such as vibration and acoustic emission
techniques due to the low instrumentation cost, smaller data size and robust signal clarity since IAS is not affected by the engine operation noise and noise from the surrounding environment. A combination of IAS and order analysis was employed in this experimental study and the major order component of the IAS spectrum was used for engine loading estimation and fault diagnosis of a four-stroke four-cylinder diesel engine. It was shown that IAS analysis can provide useful information about engine speed variation caused by changing piston momentum and crankshaft acceleration during the engine combustion process. It was also found that the major order component of the IAS spectra directly associated with the engine firing frequency (at twice the mean shaft rotating speed) can be utilized to estimate engine loading condition regardless of whether the engine is operating at healthy condition or with faults. The amplitude of this order component follows a distinctive exponential curve as the loading condition changes. A mathematical relationship was then established in the paper to estimate the engine power output based on the amplitude of this order component of the IAS spectrum. It was further illustrated that IAS technique can be employed for the detection of a simulated exhaust valve fault in this study.

Condition monitoring and fault diagnosis of diesel engines using instantaneous angular speed analysis

Research on transmission and coupling characteristics of multi-frequency pressure fluctuation of high pressure common rail fuel system

The invention relates to a grid unit particle number optimization method in rarefied airflow numerical simulation The method comprises the following steps of: judging whether the number of simulationparticles in any grid cell is within a set range or not in the numerical simulation of the thin air flow by adopting a DSMC, and if the number of the simulation particles is within the set range, notoptimizing the number of the particles in the grid cell; if the number of the simulation particles exceeds the upper limit value of the set range, repeatedly executing particle fusion operation according to a particle fusion criterion so as to enable the number of the simulation particles in each grid unit to be within the set range; and if the number of the simulation particles is lower than thelower limit value of the set range, repeatedly executing particle separation operation according to the particle separation criterion, so that the number of the simulation particles in each grid unitis within the set range; and controlling the particle number of each grid unit in the simulation domain, so that the simulation particle number in each grid unit does not change greatly along with the unit density and the unit size, and the distribution of the simulation particles on different grid units is balanced

Grid unit particle number optimization method in rarefied airflow numerical simulation

As an important part of the common-rail (CR) fuel system for diesel engines, the injector circulation capacity and the fuel injection mass flow rate vary with carbon deposition and wear, affecting ...

Investigation of fuel injection rate identification algorithm based on rail pressure fluctuation characteristics induced by injection

The invention discloses a method for automatically identifying a diesel spray crushing process and automatically realizing the spray continuous calculation. The method automatically judges the processthat a liquid film is crushed into liquid drops in the diesel injection process, and realizes a SD-ELSA algorithm of the spray continuous calculation. The SD-ELSA algorithm is characterized in that the sphericity degree and the average particle diameter of liquid phases in grids are calculated and taken as judgment bases, the information of particles in a flow field are calculated through a Lagrangian method, the information of the grids belonging to continuous liquid phases in the grid node information in the full-flow field is calculated by using an Euler model, and Euler block masses meeting two bases for determination are converted into particles and re-calculated through the Lagrangian method. According to the method, dynamic converting coupling of the Euler-Lagrangian model is realized, the complete information of discrete phases and continuous phases in the flow field can be automatically obtained and subjected to iterative computation, three stages of a liquid column, primarycrushing and secondary crushing of the diesel injection are obtained, and the diesel spray process is completely represented.

Method for automatically identifying diesel spray crushing process and automatically realizing spray continuous calculation

The invention discloses a multi-cylinder oil spraying consistency on-line diagnosis method based on rail pressure drop feature, and belongs to the field of diesel engines. During an operation processof a multi-cylinder diesel engine, an oil sprayer is prone to abrasion, so that oil spraying amounts of cylinders are different, and the rotation speed of the diesel engine fluctuates; and balance ofoperation of the diesel engine is affected. Therefore, oil spraying pulse widths of the oil spraying amounts of the cylinders of the diesel engine need to be adjusted, so that oil spraying of the cylinders is consistent. According to the method, rail pressure drops caused by oil spraying of the cylinders are taken as observation values, and the target is that the rail pressure drops caused by oilspraying are the same. Firstly, oil sprayers of the cylinders spray according to preset oil spraying pulse widths; real-time rail pressures before and after oil spraying of the cylinders are acquiredby rail pressure sensors; the rail pressure drops of the cylinders are calculated; and the oil spraying pulse widths are corrected according to the difference proportions of the rail pressure drops ofthe cylinders, so that the aim that oil spraying of the cylinders is the same is realized. By adopting the method disclosed by the invention, multi-cylinder oil spraying consistency of the diesel engine can be improved.

Wang Jing'en

Papers

Investigation of fuel injection rate identification algorithm based on rail pressure fluctuation characteristics induced by injection

Method for automatically identifying diesel spray crushing process and automatically realizing spray continuous calculation

Multi-cylinder oil spraying consistency on-line diagnosis method based on rail pressure feature caused by oil spraying