Numerical Investigation of Nozzle-Geometry Variations and Back-Pressure Changes on High Pressure Gas Injections under Application-Relevant Conditions

2018 ◽  
Author(s):  
Matthias Banholzer ◽  
Michael Pfitzner ◽  
David Sakellarakis ◽  
Yuri M. Wright ◽  
Walter Vera-Tudela ◽  
...  
Keyword(s):  
High Pressure ◽  
Numerical Investigation ◽  
Back Pressure ◽  
Nozzle Geometry ◽  
Pressure Changes

scholarly journals Cavitation patterns in high-pressure homogenization nozzles with cylindrical orifices: Influence of mixing stream in Simultaneous Homogenization and Mixing

2021 ◽  
Author(s):  
V. Gall ◽  
E. Rütten ◽  
H. P. Karbstein
Keyword(s):  
High Pressure ◽  
Process Design ◽  
High Speed ◽  
State Of The Art ◽  
Back Pressure ◽  
High Pressure Homogenization ◽  
Unit Operation ◽  
Mixing Chamber ◽  
Cavitation Intensity ◽  
Droplet Sizes

AbstractHigh-pressure homogenization is the state of the art to produce high-quality emulsions with droplet sizes in the submicron range. In simultaneous homogenization and mixing (SHM), an additional mixing stream is inserted into a modified homogenization nozzle in order to create synergies between the unit operation homogenization and mixing. In this work, the influence of the mixing stream on cavitation patterns after a cylindrical orifice is investigated. Shadow-graphic images of the cavitation patterns were taken using a high-speed camera and an optically accessible mixing chamber. Results show that adding the mixing stream can contribute to coalescence of cavitation bubbles. Choked cavitation was observed at higher cavitation numbers σ with increasing mixing stream. The influence of the mixing stream became more significant at a higher orifice to outlet ratio, where a hydraulic flip was also observed at higher σ. The decrease of cavitation intensity with increasing back-pressure was found to be identical with conventional high-pressure homogenization. In the future, the results can be taken into account in the SHM process design to improve the efficiency of droplet break-up by preventing cavitation or at least hydraulic flip.

scholarly journals Diagnostics of common rail components based on pressure curves in the fuel rail

2018 ◽  
Vol 173 (2) ◽  
pp. 3-8
Author(s):  
Mirosław KARCZEWSKI ◽  
Krzysztof KOLIŃSKI
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Dynamic Pressure ◽  
Common Rail ◽  
Injection System ◽  
Fuel Injector ◽  
Labview Software ◽  
Cr System ◽  
Data Acquisition Module ◽  
Pressure Changes

Majority of modern diesel engines is fitted with common-rail (CR) fuel systems. In these systems, the injectors are supplied with fuel under high pressure from the fuel rail (accumulator). Dynamic changes of pressure in the fuel rail are caused by the phenomena occurring during the fuel injection into the cylinders and the fuel supply to the fuel rail through the high-pressure fuel pump. Any change in this process results in a change in the course of pressure in the fuel rail, which, upon mathematical processing of the fuel pressure signal, allows identification of the malfunction of the pump and the injectors. The paper presents a methodology of diagnosing of CR fuel injection system components based on the analysis of dynamic pressure changes in the fuel rail. In the performed investigations, the authors utilized LabView software and a µDAC data acquisition module recording the fuel pressure in the rail, the fuel injector control current and the signal from the camshaft position sensor. For the analysis of the obtained results, ‘FFT’ and ‘STFT’ were developed in order to detect inoperative injectors based on the curves of pressure in the fuel rail. The performed validation tests have confirmed the possibility of identification of malfunctions in the CR system based on the pressure curves in the fuel rail. The ‘FFT’ method provides more information related to the system itself and accurately shows the structure of the signal, while the ’STFT’ method presents the signal in such a way as to clearly identify the occurrence of the fuel injection. The advantage of the above methods is the accessibility to diagnostic parameters and their non-invasive nature.

scholarly journals Numerical Investigation of Rock Breaking Mechanisms by High Pressure Water Jet

2015 ◽  
Vol 126 ◽  
pp. 295-299 ◽  
Author(s):  
Hailong Chen ◽  
Zhaomin Li ◽  
Zhihan Gao ◽  
Yuanyuan Sun
Keyword(s):  
High Pressure ◽  
Numerical Investigation ◽  
Rock Breaking ◽  
Water Jet ◽  
Pressure Water ◽  
High Pressure Water Jet

scholarly journals Polymer matrix ferroelectric composites under pressure: Negative electric capacitance and glassy dynamics

2019 ◽  
Vol 42 (9) ◽  
Author(s):  
Szymon Starzonek ◽  
Aleksandra Drozd-Rzoska ◽  
Sylwester J. Rzoska ◽  
Kena Zhang ◽  
Emilia Pawlikowska ◽  
...  
Keyword(s):  
High Pressure ◽  
Relaxation Time ◽  
Barium Strontium Titanate ◽  
Atmospheric Pressure ◽  
Polyvinylidene Difluoride ◽  
Broadband Dielectric Spectroscopy ◽  
Electric Capacitance ◽  
Barium Strontium ◽  
Spectroscopy Studies ◽  
Pressure Changes

Abstract. This report presents the results of high-pressure and broadband dielectric spectroscopy studies in polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) microparticles composites (BST/PVDF). It shows that the Arrhenius behaviour for the temperature-related dynamics under atmospheric pressure is coupled to Super-Arrhenius/Super-Barus isothermal pressure changes of the primary relaxation time. Following these results, an explanation of the unique behaviour of the BST/PVDF composite is proposed. Subsequently, it is shown that when approaching the GPa domain the negative electric capacitance phenomenon occurs. Graphical abstract

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