Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector

[EN] In this paper the experimental setup of a commercial third generation common rail solenoid injector with advanced measurement is discussed. The motion of the control piston is measured while performing injection rate investigations using a purpose-built injection rate analyzer of the Bosch type. At the same time fuel pressure in the feed line of the nozzle is gauged and contrasted to fuel pressure before the inlet connector. In contrast to the steady rise observed in a similar study, the motion of the control piston in this case is characterized by a changing gradient in the upward movement. The magnitude of the negative displacement of the upper part of the control piston due to the fuel pressure in the control volume corresponds to simulation results of the elastic deformation. Pressure before the inlet connector and pressure in the feed line exhibit a similar course with a difference in magnitude that is rising with higher rail pressures. Precisely with the end of injection the pressure in the feed line surpasses the pressure before the inlet connector for a short moment. The measurement results of control piston motion and pressure inside the injector are of particular interest because these parameters are to serve as indicators for changes in the injection rate caused by phenomena like wear and coking amongst others.The authors thank the German Research Foundation DFG for the funding of the project (reference number WA 2468/4-1) in which the here presented results originated. Furthermore, the authors thank Martin Niedermeier for the development the injector and Mario Meinhardt for the development of the data acquisition.Schuckert, S.; Wachtmeister, G. (2017). Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 569-577. https://doi.org/10.4995/ILASS2017.2017.6454OCS56957

Optical and Thermodynamic Investigations of a Methane- and Hydrogen-Blend-Fueled Large-Bore Engine Using a Fisheye Optical System

The following paper presents thermodynamic and optical investigations of hydrogen-enriched methane combustion, showing the potential of a hydrogen admixture as a means to decarbonize stationary power generation. The optical investigations are carried out through a fisheye optical system directly mounted into the combustion chamber, replacing one exhaust valve. All of the tests were carried out with constant fuel energy producing 16 bar indicated mean effective pressure. The engine under investigation is a port-fueled 4.8 L single-cylinder large-bore research engine. The test series compared the differences between a conventional spark plug and an unscavenged pre-chamber spark plug as an ignition system. The fuel blends under investigation are 5 and 10%V hydrogen mixed with methane and pure natural gas acting as a reference fuel. The thermodynamic results show a beneficial influence of the hydrogen admixture on both ignition systems and for all variations concerning the lean running limit, combustion stability and indicated efficiency, with the most significant influence being visible for the tests using conventional spark plugs. With the unscavenged pre-chamber spark plug and the combustion of the 10%V hydrogen admixture, an increase in the indicated efficiency of 0.8% compared to NG is achievable. The natural chemiluminescence intensity traces were observed to be predominantly influenced by the air–fuel equivalence ratio. This results in a 20% higher intensity for the unscavenged pre-chamber spark plug for the combustion of 10%V hydrogen compared to the conventional spark plug. This is also visible in the evaluations of the flame color derived from the dewarped combustion image series. The investigation of the torch flames also shows a difference in the air–fuel equivalence ratio but not between the different fuels. The results encourage the development of hydrogen-based fuels and the potential to store surplus sustainable energy in the form of hydrogen in existing gas grids

Optical and Thermodynamic Investigations of a Methane- and Hydrogen-Blend-Fueled Large-Bore Engine Using a Fisheye Optical System

The following paper presents thermodynamic and optical investigations of hydrogen-enriched methane combustion, showing the potential of a hydrogen admixture as a means to decarbonize stationary power generation. The optical investigations are carried out through a fisheye optical system directly mounted into the combustion chamber, replacing one exhaust valve. All of the tests were carried out with constant fuel energy producing 16 bar indicated mean effective pressure. The engine under investigation is a port-fueled 4.8 l single-cylinder large-bore research engine. The test series compared the differences between a conventional spark plug and an unscavenged pre-chamber spark plug as an ignition system. The fuel blends under investigation are 5 and 10%V hydrogen mixed with methane and pure natural gas acting as a reference fuel. The thermodynamic results show a beneficial influence of the hydrogen admixture on both ignition systems and for all variations concerning the lean running limit, combustion stability and indicated efficiency, with the most significant influence being visible for the tests using conventional spark plugs. With the unscavenged pre-chamber spark plug and the combustion of the 10%V hydrogen admixture, an increase in the indicated efficiency of 0.8% compared to NG is achievable. The natural chemiluminescence intensity traces were observed to be predominantly influenced by the air–fuel equivalence ratio. This results in a 20% higher intensity for the unscavenged pre-chamber spark plug for the combustion of 10%V hydrogen compared to the conventional spark plug. This is also visible in the evaluations of the flame color derived from the dewarped combustion image series. The investigation of the torch flames also shows a difference in the air–fuel equivalence ratio but not between the different fuels. The results encourage the development of hydrogen-based fuels and the potential to store surplus sustainable energy in the form of hydrogen in existing gas grids

Development of an Optical Investigation Method for Diesel and Oxymethylene Ether Spray in a Large-Bore Dual-Fuel Engine Using a Fisheye Optical System

Optical combustion phenomena investigation is a common tool for passenger car and automotive engines. Large-bore engines for stationary and mobile applications, on the other hand, have a lower optical examination density. This is mainly due to the technically more complex design of the optical accesses that have to provide a larger field of view and withstand high mechanical and thermal loads. Nevertheless, an optical investigation of in-cylinder phenomena in large-bore engines is essential to optimize efficient and environmentally friendly combustion processes using new sustainable e-fuels. To realize a simple optical access with maximum observability of the combustion chamber, a fisheye optic for the direct integration into internal combustion engines was developed and used for in-cylinder Mie-scattering investigations of diesel and Oxymethylene Ether (OME3-5) pilot fuel spray of natural gas dual-fuel combustion processes in a MAN 35/44DF single-cylinder research engine. As this special application of a fisheye lens poses some technical challenges, a special image processing procedure is necessary for result evaluation. This innovative postprocessing of the fisheye images comprises a calibration of the fisheye optic and a virtual three-dimensional (3D) re-projection method. Investigations prove the accuracy of the method to be within 2.1 mm. To prove the advantage of the method, optical spray investigations of two different fuels using Mie-scattering in the skipped-fire optical accessible medium-speed large-bore engine are carried out under realistic engine conditions. With the newly developed post-processing procedure, it was possible to derive the mean liquid penetration depth of the in situ investigations. Further, the post-processing includes a rectification of the fisheye images to improve the observability of the pilot fuel spray in the fired combustion engine. The analysis reveals a more compact and dense spray for OME3-5 compared to marine diesel fuel (DMA) as well as about 39% reduced liquid penetration length