search query: @keyword natural gas / total: 5
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| Author: | Künsch, Zaira |
| Title: | Experimental investigation on the gas jet behaviour for a hollow cone piezo injector |
| Publication type: | Final Project work |
| Publication year: | 2013 |
| Pages: | 65 s. + liitt. 9 Language: eng |
| Department/School: | Energiatekniikan laitos |
| Main subject: | Polttomoottoritekniikka (Kul-14) |
| Supervisor: | Larmi, Martti |
| Instructor: | Hulkkonen, Tuomo ; Sarjovaara, Teemu |
| Location: | P1 Ark Aalto 9848 | Archive |
| Keywords: | hollow cone injector gas jet laser-induced fluorescence natural gas |
| Abstract (eng): | Increased fuel consumption has strengthened concern about depletion of fossil fuel reserves and about negative impact of engine emissions on the atmosphere. As a consequence, engine developers face the challenging goal of minimising fuel consumption, while satisfying strict emission legislations and maintaining or even improving engine performance. Compressed natural gas direct-injected engines are considered a valid solution for the fulfilment of all these demanding requirements and for reducing oil dependency. For this reason, new gas injection strategies have to be developed for easing fuel direct injection and enhancing mixing process. Within this study, a hollow cone piezoelectric injector originally designed for gasoline direct injection is deployed for generating hollow cone gas jets. Liquid sprays generated through this injector type have been already investigated. However, no scientific publication provides detailed information about gas jets generated with this injector type. Objective of this work is exactly to provide first information on gas jet behaviour for a hollow cone piezo injector. Hollow cone gas jet was experimentally investigated through tracer-based planar laser-induced fluorescence (PLIF) technique. Acetone was selected as the most appropriate tracer. Acetone-doped nitrogen was injected in a constant pressure and temperature measurement chamber. The jet was imaged at different time delays after start of injection and its time evolution was analysed. Further, injection pressure and needle lift were varied and their influence on the gas jet characteristics was investigated. PLIF measurements with injection pressure ranging from 5 to 30 bar and needle lifts from 25 to 62 µm were carried out. PLIF images were post-processed and analysed and following macroscopic jet quantities were obtained: penetration length, maximal width, area, volume and average jet concentration. All these quantities provide important information on gas jet injection process, since they describe the spatial distribution of the injected gas in the surrounding air. The results show that increased injection pressure provides higher penetration length, jet width, area and volume and higher averaged jet concentration. Increasing needle lift has similar impact on the jet behaviour as increasing the injection pressure: jet penetration length, maximal width, area, and volume and jet average concentration are higher at higher needle lifts. In particular, this study illustrates that both injection pressure and needle lift variations have a greater effect on the jet maximal width than on the penetration length. This is related to the fact that higher injection pressures lower the collapsing tendency of the gas jet towards the centreline. Further, penetration length of hollow cone jets shows 0.8-power-Iaw dependency on time. |
| ED: | 2013-10-17 |
INSSI record number: 47345
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