1. GraduateResearch Assistant,StudentMemberAIAA ' Professor,MemberAIAA Copyright©2002 bytheAmericanInstituteofAeronauticsand Astronautics,Inc. Allrightsreserved. have published unsteady wall pressure data from centrifugal compressors. Hah and Krain5experimentally determined the pressure rise on the shroud of a radial compressor. Mizuki et al.6and Joslyn etal1each experimentally determined theblade pressure distribution on large centrifugal impellers with pressure tap instrumentation. These previous experimental studies serve as good comparisons to the general trends of data obtained with pressure sensitive paint.
2. The PC-PSP is prepared according to Scroggin's proceedure,23which is summarized as follows. Dispersant (D-3021, Rohm and Haas) is mixed with distilled water in a ratio of 12 mg for every gram of water. Titanium dioxide (TiO2, DuPont R-900 Ti-Pure) is then mixed into the water a little at a time by a ratio of 1.72 grams for every gram of water mixture. The resulting slurry is then ball-milled for approximately one hour to break up any agglomerates of TiO2. Polymer binder (B-1035, Rohm and Haas) is then added to the slurry at a 3-4% weight fraction, and the slurry is stirred for about two minutes. Distilled water is then added as desired to thin the slurry before it is applied to the model by airbrush spraying. To achieve uniform binder thickness and consistency, the slurry is sprayed on the model as several thin coats, waiting several minutes between each application. The luminophore used in these tests is Tris(Bathophenanthroline) Ruthenium Dichloride, (C24H16N2)3RuCl 2 from GFS Chemicals, hereafter referred to as bathophen ruthenium. The Iuminophore is dissolved in methanol, and the solution is applied to the polymer/ceramic through an eyedropper or by airbrush spraying.
3. The turbocharger used in these experiments is a Garrett T25 ball-bearing model, provided by Honeywell. This turbocharger, shown inFigure 10, is a small type typically used in automotive applications. The turbo compressor wheel has six primary blades with six splitter blades. The impeller tip radius on the primary blades is 1.03", and the blade tip thickness is 0.027". The turbocharger is mounted off-engine in a bench-top setting, as shown in the diagram of Figure 11 and the picture of Figure 12. Compressed air from the building shop air supply is used to drive the turbine. The air supply provides sufficient airflow to drive the turbocharger to speeds in excess of 100,000 rpm at almost all operating conditions. Lubrication is provided by a Greylor PQM-1-120 gear pump, which circulates Mobil 1 OW-30 synthetic oil through the turbo at about 30 psi. Control of Operating Point
4. The operating condition of the turbocharger is set by controlling the flow rate of the air driving the turbine, and by creating a pressure drop at the compressor inlet. The turbine supply is controlled through an air regulator. The compressor inlet pressure drop is controlled through the placement of a series of fine-mesh screens over the inlet. An acrylic tube measuring 12" long, 2-1/4" OD, and 1-7/8" ID is fit in the compressor inlet, with the screen mounted at the end of the tube. The screen size is chosen to produce the desired pressure drop, with finer mesh screens giving alarger pressure drop. Instrumentation