Minisimulator for evaluating high-temperature candidate lubricants: part I- Method development

A new turbine engine lubrication system simulator was developed for assessi ng coking performance of high-temperature fluids of limited quantity. The s ystem, constructed from corrosion-resistant material, can use less than one liter of fluid to lubricate two 30-mm bore, angular contact ball bearings under a 100-ksi Hertz stress. Testing has been done at bearing speed's of 1 0,000 rpm with bearing temperatures as high as 360 degreesC for polyphenyl ether fluids. Oil samples are periodically drawn from the heated lubricant sump to measure viscosity changes. A demerit system was used to rate the se verity of deposits formed on test head components. To help ensure repeatabl e test results, modifications were made to the test head assembly to improv e temperature control of all critical sections. Initial tests of polyphenyl ether at 300 degreesC bulk oil and 360 degreesC bearing temperatures have shown that their deposit tendency could be characterized under dynamic cond itions.