After an aero-engine shuts down, the high temperature within the core flow path prevents conventional borescope probes from performing immediate internal inspections due to their limited thermal resistance, thereby constraining rapid turnaround capabilities for aircraft. To address this challenge, this study proposes an active cooling strategy using coolant flow to keep the probe within a safe temperature range. Three cooling structures incorporating pressure-drop modules—annular, annular-slit, and round-hole configurations—were designed and numerically investigated to assess the effects of geometric parameters and coolant properties (temperature, pressure, nitrogen mixing ratio) on cooling performance. The results demonstrate that the round-hole structure with a 1.0 mm diameter achieves optimal cooling, maintaining an average probe mirror temperature of 286.2 K under coolant conditions of 285 K and 0.5 MPa. Cooling efficiency exhibits a strong linear negative correlation with coolant temperature, while its relationship with pressure is highly structure-dependent. Nitrogen doping significantly improves the heat transfer capacity of the coolant. The implemented three-stage pressure-drop module performs consistently, with the pressure loss per stage determined solely by the inlet pressure. This study provides valuable insights and a theoretical foundation for the design of high-temperature-resistant borescope equipment capable of operating in the harsh environments of aero-engines.

Aircraft engine endoscope probes often face difficulties in effectively detecting internal structures in high-temperature environments. In order to improve the thermal protection characteristics of endoscope probes, this paper designs a probe-cooling structure with a circular ring pressure drop structure and calculates and analyzes the cooling effect of the probe under different gas cooling conditions. Study the influence of size parameters and cooling medium properties of the structure on the cooling characteristics of the probe, analyze the temperature distribution of the probe mirror, cooling efficiency distribution, and cold flow outlet flow distribution. The results show that the larger the outlet width of the annular cooling structure, the better the cooling effect, and the optimal cooling effect structure is 0.7 mm; the larger the opening angle, the lower and then the higher the temperature of the endoscope probe surface, and the best cooling effect occurs when the optimal angle is 40°; the larger the proportion of mixed liquid nitrogen, the lower the temperature of the probe mirror surface. A 5% proportion of mixed liquid nitrogen can reduce the temperature of the probe mirror surface by about 11 K.