Variable Throat Nozzle Needle for Spacecraft Thruster Flow Control

The patent applies the dynamics principle by making the nozzle throat section variable through a movable needle that can shift between positions. The needle is actuated by pressure differential across it, automatically adjusting the throat area to match combustion chamber pressure conditions. This dynamic adjustment enables optimization of thrust coefficient for both high and low flow rate operations, transforming a static structure into an adaptive one.

The patent implements self-service by designing the needle actuation mechanism to be automatically controlled by the combustion chamber pressure itself. The pressure differential across the needle (higher pressure on one side, lower on the other) naturally drives the needle to the appropriate position without requiring external actuators, control systems, or power sources. The system uses its own operating parameter (pressure) to control its own adjustment, eliminating complex control mechanisms.

The patent applies parameter changes by utilizing the thermal and mechanical properties of the needle material under different operating conditions. When the needle is in axial abutment against the neck during low flow operation, the large contact surface area provides enhanced heat exchange, allowing the needle to dissipate heat more effectively and resist thermal degradation. The same geometric configuration also provides mechanical support that resists erosion from combustion gases. The system leverages changes in operational parameters (needle position) to access different physical property regimes.