Injection & sprays

Main features:

• 5 independent EVI and 1 EMI devices are available
• In-house developed software to obtain the injection rate shape
• Simultaneous mass flow measurement to validate the results with estimated speed of sound
• Injection control devices for Bosch, BorgWarner, L'Orange, OMT fuel injection systems (piezo and solenoid)
• Controllable discharge pressure up to 180 bar to simulate engine conditions
• Experience with H2-ICE

Objectives

• Rapid determination of injection rate
• Search of injection system configuration for injection system behaviour improvement
• Influence of fuel properties on injection rate (biodiesel vs std diesel)
• Influence of temperature on dynamic behaviour

Main Features

• One-dimensional unsteady model solving the mass and momentum conservation equations. (AMEsim, Flowmaster, GT-Suite)
• Validation of each of the parts of the injection system and all the system
• Modular structure to build any injection system (line pump, rotative pump, common rail, injector nozzle, injector body, pressure regulator...)
• It calculates the unsteady fluid-mechanics and dynamic behaviour
• Applicable to either standard solenoid-operated injectors or last generation piezo-operated injectors

Example of 1D modelling of a solenoid injector using Simcenter Amesim code

• Electrovalve, Injector holder and injector nozzles 1D-modelling approach using elements of Simcenter Amesim from different libraries: control, hydraulics, mechanics,etc

Example of results

• Comparison between an experimental mass flow rate and that obtained with the Amesim model once has been build and calibrated.
• The model results are highly reliable even for very small injection pulses affected by injector dynamics

Objective:

• Temperature controlled atmosphere (Up to -30 ºC) and low relative humidity

Posible studies:

• Stability test
• Engine warm up test
• Optimization of Injection strategies for cold climates
• Influence of temperature on injection rate
• Fuel behaviour under cold and hot conditions (bio-fuels)

Example of results

• Influence of temperature on injection rate at -20ºC, 0ºC, and 30ºC
• Temperature strongly affects fuel viscosity, which in turn affects injector dynamics and ultimately the injection rate

Main chracteristics

• A special silicone is introduced inside the Diesel nozzle in order to obtain the internal characteristics
• The silicone mould is taken out and analysed in an electron microscope
• Accurate and necessary information in order to perform any analysis on Diesel nozzles

Main Characteristics

• Modification of the injector holder. No needle
• Constant inlet and outlet pressure conditions
• Continuous mass flow
• A commercial CR system is used
• It is possible to characterize any type of nozzle from any supplier

Objectives

• Detailed 3D flow modelling
• Analysis of nozzle flow characteristics and cavitation phenomenom
• Correlate orifice permeability with internal flow
• Correlate with spray behaviour, mainly atomization and air entrainment

Main features

• Simultaneous resolution of all conservative equations
• Selectable algorithms with different time/space discretization order
• Cavitation sub-model

Example of results

• Large Eddy Simulation (LES) for the study of gasoline jet injection with a flash-boiling sub-model
• The use of Large Eddy Simulation allows to study the turbulence development and its interaction with the flashboiling phenomenon and opening/closing transients
• The image shows different spray evolution times after the start of injection (SOI)

Main features

• Piezo-electric sensor. Force sensor witch directly measures the momentum flux
• Pressurized with Nitrogen
• Maximum pressure inside the chamber 100 bar
• Continuous fuel evacuation system
• Characterization of multihole nozzle: Hole to hole vaiations are evaluated

Examples of results

• Comparison of dispersion in momentum flux measurement between orifices in a used nozzle versus a new nozzle
• Deposits of soot and other additive particles from fuel and/or oil cause dispersion in the captured signal
• In the new nozzle, deviations between orifices in the manufacturing process and, especially, the hydro-grinding process itself generate a small dispersion in the momentum flux measurement captured downstream of the spray

Procedure

• Outlet velocity can be estimated by means of the combination of momentum flux and the mass flux
• Coefficients: real value divided by the theoretical value

Main features:

• Gas: N2
• Pressure: 20-60 bar
• Isothermal conditions
• Test frequency < 1 Hz
• Pulse generator to operate the injector

Possible measurements

• Spray visualization for multi-hole nozzles
• Microscopic visualization of the start of injection process

Application example

• Comparison of the morphology and macroscopic aspects of the spray from a VCO nozzle versus a micro-sac nozzle

• This vessel and optical technique enable the visualization of the spray in the near field of the nozzle (field of approximately 2mm)
• Automatic system, that includes illumination, focal lens and automatic coordinate system
• Pulsed Nd-Yag Laser with a light diffuser
• High spatial resolution (up to 250 pixels/mm)

Application example

• Direct Numerical Simulation of a free spray of dodecane injected at 100 m/s into ambient air
• Mesh size of around 700 million cell with a cell size of 2 micrometers simulated on the Marenostrum 5 supercomputer at Barcelona Supercomputing Center (BSC) of the RES (Spanish Supercomputing Network)
• To take into account turbulence in the nozzle, a Large Eddy Simulation (LES) simulation has been mapped as boundary conditions at the domain inlet (nozzle outlet)

New PDA processor by DANTEC

• Phase Doppler signal processor: BSA F/P 800
• Maximum sampling frequency: 600MHz
• Maximum processable frequency: 200MHz
• Minimum transit time:42 ns
• Velocity range: -30 to +300 m/s
• Diameter range: 0.5 to 200 μm
• Measurement limit on-axis: 20 mm from orifice, function of orifice diameter, injection pressure and ambient density

High Pressure and High Temperature Test Rigs with optical Access. Two facilities IAPAT 1 and IAPAT 2 which differ in size and maximum chamber temperature (1000K vs. 1100K)

• Used for experimental study of the injection-combustion behaviour
• Large range of controlled thermodynamic conditions including those typical of engine: (10 < P < 150 bar, 300 < T < 1000K)
• Possibility to use different fuel injection systems (any spplier)
• Possibility to use different fuels (Diesel, biodiesel, gasoline, ethanol, natural gas, OMEx, Methanol, H2, NH3, etc

Setup and obtained results sample

• Optical arrangement for Schlieren technique, with an example image obtained at a specific moment in time, representative of vapor penetration
• The figure below on the right shows a comparison of liquid penetration obtained using the diffusive back illumination (DBI) technique and vapor penetration obtained using Schlieren

Study of flash boiling in GDI injectors using the Schlieren technique

• Example of spray morphology for different injection pressure conditions and thermodynamic conditions in the chamber using diffusive back-illumination (DBI) (two images at the top) and Schlieren technique (two images at the bottom)

Facility for studying ammonia injection-combustion in high-power engine injectors

• Liquid ammonia is supplied from a storage tank -> NH3 cooled down to prevent cavitation in the pump
• A pneumatuc pump is used
• To prevent phase change in the injector
• All the return lines are collected -> acid trap

Comparative study of diesel and ammonia sprays using DBI and Schlieren techniques to determine liquid and vapor penetration

• Spray penetration results showed significant differences between NH3 and conventional diesel (used as reference), especially in the transient phase of the process

Characterization of hydrogen jet as a function of time for different temperatures

• Temperature has a significant effect on both penetration and jet volume

Natural luminosity and OH* radicals chemiluminescence

• Fast camera captures natural combustion luminosity
• Intensified camera with 310 nm filter captures OH* luminosity
• Examples of images captured by the cameras used in both techniques are shown on the right

Main characteristics:

• OME: mix of OME3 to OME3
• No carbon-to-carbon bonds -> No direct formation of soot precursos
• High molecular oxygen content -> Rapid oxidation
• High reactivity fuel is suitable for combustion modes based on autoignition
• Challenges -> Lower Heating Value and viscosity

Overlaid Schlieren + OH*:

• Before ID: No fuel effect on spray behavior
• After ID: Shorter ignition produces faster penetration, but other parameters may affect

Examples of results obtained using the Laser Induced Incandescence (LII) technique

• Volumetric fraction of soot present in the flame for different injection pressures and time elapsed after the start of injection (ASOI)

Main features

• Use of transparent wall to study the impact of the spray on the wall
• Versatile installation with the possibility of changing the angle of the wall and therefore the interaction between the spray and the wall

Samples of captured images

• Example of interaction between a dodecane spray and a wall positioned at an angle of inclination of 60º
• The left image shows the side view and the right image shows the front view captured thanks to the transparency of the wall
• The camera is located behind the wall and the wall is between the spray and the camera