Additive Manufacturing and Hot Fire Testing of Complex Injectors With Integrated Temperature Sensors

The article presents an exploration of design and prototyping of oxy-fuel injectors with integrated temperature sensing capabilities using powder bed fusion additive manufacturing (AM) technologies. A primary focus of this work was to develop powder removal techniques to completely remove sintered powders from internal cavities, which facilitated the implementation of complex injector geometries as well as sensor placements within the parts. It was found that submerging the part in liquid nitrogen, in combination with exposure to ultrasonic vibration, provided effective powder removal. Mechanical testing of fabricated components and test coupons showed no significant change in the mechanical strength of the part due to the addition of liquid nitrogen which creates a thermal shock. Metallography and powder characterization through the use of SEM and EDS showed no change in metallurgical properties of the parts due to the use of liquid nitrogen and ultrasonic energy. The injectors were then test fired in both atmospheric and high-pressure conditions at different firing inputs (55–275 kW).