IN FLIGHT EXPERIMENTATION FOR THE IXV RE-ENTRY VEHICLE: OBJECTIVES, EXPERIMENT DESIGN AND IMPLEMENTATION

摘要

This paper describes the In-Flight Experiments system (IFE) foreseen for the (ⅩⅣ) Re-entry Vehicle.The (ⅩⅣ) re-entry vehicle is a 4.4 meter long slender body which is fully instrumented to capture details of itsperformance during the 30 minute hypersonic re-entry. Acquired data are recorded at a rate of 1-10 Hz until splashdownand transmitted to earth via telemetry. A transmission delay is implemented during the black-out phase. Themeasurements characterize the overall heating behaviour and performance of the thermal protection system (TPS) whilealso capturing aero-thermodynamic phenomena such as catalytic heating and shock-boundary layer interactions.The objective of the sensor definition and placement in the vehicle is to maximize the amount of data while minimizingthe number of sensors. A total of 20 thermocouples and 9 pressure sensors are used in the nose cap to capture angle ofattack, stagnation pressure and thermal gradients of the SepcarbInox? C-SiC composite. Displacement sensors and hightemperature strain gauges record mechanical loads and measure the differential expansion between the nose cap and thevehicle structure. A combination of sensors is also used in the windward TPS to measure gradients, pressures and steps.A coated patch is applied on one of the panels to quantify the catalytic level of the ceramic material during re-entryThe leeward, lateral and base of the (ⅩⅣ) vehicle are covered by ablative material. Its behaviour requires a dedicateddesign of the thermocouple measuring system. At the rear of the vehicle the flaps and hinge are instrumented usingthermocouples in a guiding system that allows unimpeded flap movement. An infrared camera with periscope opticsbased on a sapphire mirror generates thermal maps of the flaps. The derived thermal maps are then used to determine thewindward temperatures using inverse methods. The infrared optics integrates a rotating pass filter allowing independentmeasure of temperature and emissivity. Images are compressed for transmission and stored in the data handling unitwhich analyzes them and sets gain and exposure of the camera.The dimensioning driver in the design of the sensors is the high thermal flux sustained during the 30 minute re-entry.