More light: LED spot illumination makes engine development easier

Winterthur, June 2020 – Very high-intensity light sources from Kistler provide support for high-speed engine measurements that deliver critical information. High luminance levels make it possible to carry out high-resolution optical analyses of processes in the combustion chamber. And illumination systems in the LED-P series also bring their strengths to bear in many other applications.

Today's high-speed cameras feature ultra-short exposure times that open up new horizons for image data acquisition in combustion engines. For example, injection events can be recorded with absolute precision. As well as the camera itself, the right illumination is a critical factor in image quality: the combustion chamber must be illuminated with precise timing so that images of sufficient brightness and clarity can be captured.

The standards of efficiency required in modern engine development have made it increasingly uneconomical to use 'transparent engines': they are too costly and too time-intensive, and they cannot fully replicate practical conditions. To solve this problem, developers are making more use of endoscopy or borescope systems: with this method, images are captured and illumination is provided through small access bores into the combustion chamber. The illumination units in the LED-P series from Kistler were specifically developed to capture high-speed endoscopic images in combustion engines.

Shedding light on every detail

At the heart of these illumination units are high-performance LEDs that deliver very high light output. Extensive adjustment options allow both continuous and pulsed illumination: significantly higher light intensities are achieved in pulsed mode. Various configurations can be set via software, and users can switch between them quickly at any time.

The light radiated by the LEDs is fed into fiber optic bundles so that it can be flexibly directed to the spot that needs to be illuminated. The benefits: accurately targeted illumination, and the ability to transmit the radiated light over longer distances. Also, optical units from Kistler are specifically designed to cope with the harsh environment in combustion engines, where individual components are exposed to very high pressures and temperatures.

Intensive, individual illumination for long periods

The LED-P series from Kistler includes three standard versions that can be equipped with one (P40), two (P80) or four (P160) LED chips according to choice. The number of LEDs determines the output power for the illumination. These three models can cover many different combustion engines. For large industrial engines – to take one example – the P160 model is used: this version has four LED chips to deliver the highest power in the range, and it can illuminate the entire combustion chamber. All three versions share these benefits:

• Very high illumination intensity
• Compact design
• Constant light output throughout the period of operation
• Long lifetimes
• High-performance connectivity via Ethernet
• Convenient remote control and configuration via software
• Trigger input for synchronization with camera and engine

LEDs can replace lasers – and they are more cost-efficient

Models in the LED-P series are suitable for use in many other applications as well as combustion engine illumination. For instance, small areas can be illuminated perfectly to examine painting, coating, varnishing or welding processes with high temporal resolution. There are many application areas where high-performance LED illumination from Kistler can replace conventional laser illumination. Users benefit in two ways: there are no safety concerns with the LED-P series from Kistler, and these light sources are more cost-efficient than lasers.

LED systems from Kistler are compatible with coupling inlets from other manufacturers, and they can be configured individually. They are also integral components of the HIS high-speed camera system: the solution that gives customers a complete measuring chain to record events in the combustion chamber. Kistler also offers numerous additional products including suitable optical probes and borescopes, as well as an extensive range of software for data acquisition and analysis.

And by no means least: Kistler's team of optical combustion analysis experts are always standing by to advise and assist customers with any questions about applications for these products. Kistler offers a complete range of services including design support, product training and assistance with large-scale measurement assignments.