Yuanyuan Li

Bent heat pipes in spacecraft thermal-control systems are often exposed to spatially distributed heat loads, but the combined effects of bend geometry and heat-source arrangement remain poorly quantified for aluminum-ammonia axially grooved heat pipes. Here, horizontal experiments and a three-dimensional volume-of-fluid model were used to examine single bends of 45°, 90°, and 135°, multiple-bend configurations, and four heating arrangements ranging from continuous to discrete sources. Transient and steady wall temperatures, axial temperature uniformity, thermal resistance, equivalent thermal conductivity, and the heat-transfer limit were evaluated. The numerical results were used to interpret curvature-induced secondary flow, vapor-liquid distribution, and pressure loss. The 90° single-bend pipe had the lowest measured thermal resistance at intermediate heating powers, whereas larger bend angles and repeated bends lowered the limiting heat load. Distributing the heat input also improved performance: the four-segment configuration increased the measured heat-transfer limit by approximately 21% relative to continuous heating. The two-end configuration had the lowest thermal resistance over the tested range, although its limiting heat load could not be measured because of the heater capacity. These findings quantify the trade-off between routing geometry and heat-load distribution in grooved heat pipes for spacecraft thermal control.

This work aims to study the dynamic characteristics of an entire aero-engine casing by experiments using a new type of rotating exciter. New vibration sensor layout rules are proposed according to experimental results and vibration transmission characteristics. The vibration response of the aero-engine casing is carried out, and the vibration response of different casing measuring points is also studied. The finite element model of the engine casing’s structure is established to obtain the natural frequency of the whole aero-engine casing, which agrees well with the experimental measurement. We find that the vibration acceleration transmission value of the radial measuring point of bearing No. 1, but not the fan sensor, is more suitable for detecting the running state of the fan rotor. In addition, the sensor in the intermediate casing can detect the vibration of the high-pressure rotor. Bolt loosening of the flange has little effect on the vibration transmission characteristics of the casing. This work aims to provide experimental data of whole aero-engine vibration characteristics with a new rotating exciter for the vibration test, which can help optimize the location of the vibration transducer for the engine and the assembly technology design for the whole engine structure.