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3D Particle Image Velocimetry Flow Test Rig

Objective

The aim of the 3D Particle Image Velocimetry Flow Test Rig is to evaluate the intake ports regarding the cylinder charge motion as:

  • mass flow rate
  • axial, tangencial, and radial velocity components

 

Particle Image Velocimetry Particle

Particle Image Velocimetry (PIV) is a non-intrusive optical technique that measures two velocity vector components simultaneously over an two-dimensional flow area. Tracer particles are introduced into the flow, and their scattered light are imaged by high resolution camera at two points in time close to each other. Short pulse illumination (pulsed laser) is used to “freeze” particle motion. Their displacements are then calculated statistically over a grid, for each grid cell area. Knowing the pulse separation and the image scale, the displacement field can be converted into a velocity vector field.

Stereo Particle Image Velocimetry

In stereo PIV two (or more) camera perspectives are used to obtain different projections of three-dimensional particle motion. The projection of three dimensional motion along the different camera perspectives results in measureable particle displacements which may be combined to obtain an unambiguous measurement of three-components of displacement and from this three-components of velocity. The optimal angular separation for measuring all three components of velocity is 90 degrees and for a standard camera arrangement where the image and lens planes are parallel it will not be possible to achieve good focus over the whole of the imaged measurement plane. This problem is rectified by tilting the image plane such that the plane of the light sheet, the lens and the image plane intersect at a point. This is termed Scheimpflug tilt and as well as allowing particles over the whole image plane to be focused properly also introduces a perspective distortion.

Characteristic numbers

Evaluated numbers from flow test data:

  • discharge coefficient (αK)
  • ca (average axial velocity)
  • Swirl
  • Tumble
  • Cross-Tumble
  • Swirl for y+/y-

Setup


Blower

  • Manufacturer: Becker
  • Speed: 2800 / 3300 min-1
  • Inlet capacity: 1050 / 1250 m³/h
  • Pressure: + 135 / 95 mbar
  • Vacuum: – 165 / 135 mbar


Rotary Piston Flow Meter

  • Manufacturer: Aerzener
  • Volume: 11.0 dm³
  • Qmax: 1000 m³/h
  • Qmin: 10 m³/h
  • Pmax: 10 bar


Particle Generator

  • Manufacturer: ILA
  • Operation principle: Laskin atomizer nozzles
  • Tested seeding materials: DEHS, and vegetable oils
  • Typical particle size: 1 μm (peak in PDF of size distribution)
  • Typical seed output per jet: appr. 108 particles/second
  • Operating pressure: up to 3 bar overpressure on the vessel, inlet pressure 0.7 – 1.0 bar.


Laser System

  • Manufacturer: New Wave
  • Model: Solo 120 XT
  • Repetition rate: 15 Hz
  • Energy: 120 mJ per pulse @ 532 nm
  • Energy stability: +/- 4% @ 532 nm
  • Beam diameter: 4.5 mm
  • Pulse width: 3 – 5 ns
  • Divergence: < 3 mrad


CCD Cameras

  • Manufacturer: PCO
  • Model: pco.1600
  • Resolution (hor x ver): 1600 x 1200 pixel
  • Pixel size (hor x ver): 7.4 x 7.4 μm2
  • Dynamic range A/D: 14 bit
  • Frame rate: 30 fps
  • Exposure time: 500 ns … 49 days
  • Lens: Canon EF 35mm f/2


Cylinder and Cylinder Head

  • Cylinder liner made of Plexiglas
  • Bore dimension up to 140 mm
  • Maximal cylinder head height: 260 mm
    Maximum cylinder head length: 1200 mm

Some Facilities

  • Automatic positioning of camera/laser
  • Very precise remote focus and aperture control
  • Unit controlled by PC
  • Particle supply controlled by PC
  • Easy cylinder head/ liner changes
  • Test rig control and data acquisition
  • VidPIV 4.6 software
  • Picture generation macros
  • Sucking or boosting operation
  • Scheimpflug adapters and perspective distortion correction

Application

  • Validation of cylinder charge motion CFD models
  • Numerical predictions (spray + charge motion), such as wall film formation and homogeneity of mixture