QMT Features: December 2014
BLOODHOUND 1,100mph wheel spin test
Micro-Epsilon sensors are helping the land speed record attempt

Micro-Epsilon UK Ltd has supplied a variety of non-contact laser displacement sensors and an infrared thermal imaging camera for use in a high speed (up to 10,500rpm) wheel spin test, part of the BLOODHOUND SSC Project – the 1,000 mph land speed record attempt that is scheduled to take place in 2016.

The wheel spin test, which took place at Rolls-Royce’s test facility in Derby, was carried out on the first of the BLOODHOUND machine’s four solid aluminium wheels. The Rolls-Royce facility is normally used to test jet engine fans and turbines in a vacuum, but on this occasion the wheel spin test was the highest ever rpm recorded on the test rig.

The objective of the wheel spin test was to verify that the growth (expansion), temperature increase (due to air friction) and vibration of the wheel were within expected, safe limits and whether these test results would closely match the BLOODHOUND Team’s own predictions using computer simulation and FEA software.

For the wheel spin test, Micro-Epsilon UK supplied a total of 15 laser displacement sensors from its optoNCDT series, as well as a thermoIMAGER TIM 450 compact, high resolution infrared imaging camera.
Of the 15 laser displacement sensors provided, 9 x optoNCDT 1700 sensors with a measuring range of 10mm were set up on the test rig to measure the radial and axial run out of the aerospace-grade aluminium (Al 7037) wheel as it rotated at speeds of up to 1,100mph (the wheels will travel at speeds up to 1,000mph during the supersonic machine’s record breaking attempt). In addition, 2 x optoNCDT 1700 laser displacement sensors with a measuring range of 2mm were set up to measure the thermal expansion of the frame that runs across the top of the test rig (i.e. for test rig calibration purposes).

In addition to the optoNCDT 1700 sensors, the test rig was also equipped with four optoNCDT 1402 laser sensors (with a measuring range of 5mm), which were mounted underneath the test rig in a confined space. These sensors measured the run out, alignment and any other movements of the test rig, including the steel hub that the wheel is mounted to.

Micro-Epsilon also supplied its thermoIMAGER TIM 450 infrared imaging camera for the wheel spin test.
As Glenn Wedgbrow, Sales Manager at Micro-Epsilon UK Ltd comments: “The thermoIMAGER TIM 450 camera was chosen for this task mainly because of its high resolution and its compact design, which enabled the camera to be set up in the floor panels underneath the test rig, looking up across a very wide field of view from a short standoff distance to measure the temperature of the complete radius of the wheel.”

During the test, the wheel was successfully spun to 10,429 rpm (174 revolutions per second). Test results were similar to the predictions that the BLOODHOUND engineers had calculated using their computer simulation software. The expansion of the wheel’s 902.6mm diameter by 1.6mm was as expected. So too was the “dishing” of the wheel caused by a variation in expansion rates between the aluminium material of the wheel and the steel hub. The empirical data collected during the test will now be used to fine-tune the computer simulations, delivering a more optimum wheel design.
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