1. The test system is instrumented as follows. Prcssurc in the chamber and pressure to the air actuator are measured using bonded strain gauge pressure transducers. The temperztLire of the GO, environment and the temperature at two locations on the fixed test sample (see Figure 71 are measured usin? 304 Stainless Steel sheathed Chromel-Alumei thermocouples. The usable temperature measurement range is 0-2200°F. The chamber is provided with a thermopile to detect changes in heat radiation from the rubbing samples. Interface ioad and torque are measured with specifically positioned load cells. Axial displacement of the rotating shaft is measured using a linear displacement transducer which provides a measure of sample wear andlor sample consumption during burning. Sample surface speed is determined from an rDm sensor and sample radius.
2. The PIT test system consists of a 2-in.dia (O.D.), 3-112-in.long stainless steel chamber, see Figure 14. connected to a high-flow, highpressure, high-temperature GO, supply. The chamber contains an inner cylindrical cavity which is 314 in. in diameter and 1 in. long. An orifice assembly is placed at the upstream end of the cylindrical cavity and a target impact plate (test sample) is placed at the downstream side. Three
3. The test procedure involves the preheating of the test specimen for 10 and 30 scc with GO, foliowed by sequential injection of 10 particles of aluminum of 1500 ir m diameter. Temperature data from the calibration run established the preheat timc. The calibration measurements revealed a standing shock wave ahead of the impact plate. A stagnation pressure of 1700 psia was measured when the pressure upstream of the nozzle reached 4500 psi. Thc downstream plenum pressure was 500 psia, as illustrated in Figure 14. Temperatures at the impact plate typirally run 40 to 70OF higher than the stream temperatures measLired in thc upstream flow.
4. Aprevious tcst program (Reference 5 ) at the same facility conducted screening tests of candidate particle naterials and sizes. In this earlier program, thc materials anrJ particle sizes evaluated in thc screening process were selected based on sizes and types anticipated to bc found in the Space Shuttle Main Engine propulsion systcn and led tu the selection of 2024 Aluminum, and Inconel 718 at the 150 and 800 micron level. The screcninn test data showed that aluminum and Iaraer previous test series of 550°F. The present ;proqram utilized 1500-nicron aliiminum alloy particles propelled by 0500 psi 0, at temperatures LIP to 800OF.