An inductive clearance measurement sensor has advantages of good anti-interference, fast response speed, and high sensitivity, and it has obvious technical potential in aeroengine turbine tip clearance measurement. In this paper, a rotor dynamic tip clearance measurement experiment system was designed based on a high-resolution inductive measurement system. The high temperature calibration experiment, performance verification experiment, and dynamic clearance measurement experiment under varying operating conditions were used to verify the high-temperature dynamic measurement performance of the measurement system. The resolution was used as the evaluation parameter of measurement performance. The experimental result shows the system has good resolution and dynamic response at 1000 °C, and the dynamic resolution reaches 10 μm in the 3 mm measuring range. The varying condition experiment results show that the blade deformation caused by the speed change of 1000–3000 r/min and the temperature change of 600–1000 °C can be resolved, and the resolution reaches about 10 μm. The research results verify that the inductance clearance measurement system has the characteristics of high temperature resistance and high resolution, and the technical specifications of clearance detection meet the basic requirements of dynamic clearance measurement of turbine tips, which provides an effective detection method for aeroengine health monitoring.

Morphological characteristics of coarse aggregates, namely shape, angularity and surface texture, are closely related to rock mineral compositions and crushing mechanisms. Aggregates with different mineral compositions should be crushed using a suitable crusher. To explore the influence of mineral and crusher types on aggregate morphology, this study investigated the effect of the mineral compositions and crushing operations on the morphologies of coarse aggregates. Six types of major rock-forming minerals (i.e., quartz, amphibole, potassium feldspar, sodium feldspar, calcite and pyroxene) were selected and two typical crushers (i.e., jaw crusher and impact crusher) were used. The morphology parameters (i.e., angularity, texture, sphericity and F&E) of coarse aggregates were measured using the Aggregate Image Measurement SystemII (AIMSII). Further, the morphologies of different aggregates produced by two crushers were compared. The results showed that the angularity values of some aggregates crushed by a jaw crusher (average 3451) were bigger than those by an impact crusher (average 3067) and the angularity of the harder mineral was less affected by the crusher. For surface texture, there was no significant difference between these two crushers, with average texture index of 333.83 for the impact crusher and 332.67 for the jaw crusher, indicating that the surface texture of aggregates was mainly affected by their compositions and barely influenced by the crushing operations. The shape results indicated that the impact crusher produced more cubical aggregate particles compared to the jaw crusher, with average sphericity of 0.666 versus 0.607, whereas the jaw crusher produced aggregates with more elongated or flat particles, with an average F and E index of 3.331 versus 2.726. This study fills the research gap that few previous investigations focused on—the crushing morphology of single mineral aggregates—and the findings help us to understand the effect of the mineral compositions and crushing operations on the morphologies of coarse aggregates, which in turn guides the selection of suitable crushers for different minerals.