FASTCAM MINI CX: Photron is very pleased to announce the upcoming release of our new FASTCAM Mini CX high-speed camera. Ideally suited for both on-board and off-board vehicle safety testing, the Mini CX delivers an exceptional combination of resolution, frame rate, light sensitivity and durability in a compact, stand-alone package.

With 1080 HD resolution at 1,000 frame per second and an industry leading light sensitivity of ISO 5,000 color and ISO 10,000 monochrome, the Mini CX provides outstanding image quality. Designed for the space limited locations and High-G operating environments common to vehicle safety testing, the Mini CX is Photron’s smallest, lightest and – with operational testing to 150G – most rugged camera.

Additional features add to the usability of the Mini CX in automotive environments. HDMI video output allows easy local focusing of the camera. An internal battery offers 30 minutes of camera operation if the primary power source becomes detached during a test. Rapid download to nonvolatile memory ensures protection for recorded images. A built-in accelerometer provides a backup trigger source.


Pulse train ignition with passively Q-switched laser spark plugs

ABSTRACT : Leaner burning and downsizing are two concepts pursued by engine developers to reduce fuel consumption and emissions. Both approaches lead to increasing challenges concerning ignition, as these concepts are typically associated with an increase in flow velocity and degree of turbulence as well as raised pressure at the moment of ignition. In this context, the use of miniaturized passively Q-switched laser spark plugs with pulse train ignition is considered as a promising alternative to conventional spark plugs.However, the application of these passively Q-switched laser spark plugs inevitably leads to the question of optimum pulse train parameters. For a better understanding, this study deals with improved flame formation by passively Q-switched laser pulse train ignition under engine-like conditions. The entire ignition process is investigated with a special focus on interactions of consecutive pulses. Therefore, three methods are combined: energy transfer measurements from laser pulse to plasma with high temporal and spatial resolution show the breakdown process depending on different pressures and fluid mixtures. The temperature decrease in the induced plasma is analyzed with measurement strategies for temporal high-resolved plasma spectroscopy especially adapted to passively Q-switched lasers. In combination with high-speed schlieren measurements, the changing local ignition conditions during pulse train ignition are demonstrated. The experiments show how consecutive pulses interact and contribute to the ignition in case of a gas flow. The used prototypes of laser spark plugs are provided by Robert Bosch GmbH.
Read the full paper here.

Unsteady flow measurements in the wake behind a wind-tunnel car model by using high-speed planar PIV

ABSTRACT : This study investigates unsteady characteristics of the wake behind a 28%-scale car model in a wind tunnel using highspeed planar particle image velocimetry (PIV). The car model is based on a hatchback passenger car that is known to have relatively high fluctuations in its aerodynamic loads. This study primarily focuses on the lateral motion of the flow on the horizontal plane to determine the effect of the flow motion on the straight-line stability and the initial steering response of the actual car on a track. This paper first compares the flow fields in the wake behind the above mentioned model obtained using conventional and high-speed planar PIV, with sampling frequencies of 8 Hz and 1 kHz, respectively. Large asymmetrically coherent flow structures, which fluctuate at frequencies below 2 Hz, are observed in the results of highspeed PIV measurements, whereas conventional PIV is unable to capture these features of the flow owing to aliasing. This flow pattern with a laterally swaying motion is represented by opposite signs of cross-correlation coefficients of streamwise velocity fluctuations for the two sides of the car model. Effects of two aerodynamic devices that are known to reduce the fluctuation levels of the aerodynamic loads are then extensively investigated. The correlation analyses reveal that these devices indeed reduce the fluctuation levels of the flow and the correlation values around the rear combination-lamp, but it is found that the effects of these devices are different around the c-pillar. Read the full paper here.