Novel Design of Orifice Type Control Element for Mitigating Instabilities

An orifice element is commonly used in liquid rocket engine test facilities to provide a large reduction in pressure over a very small distance in the piping system. Orifice elements are used in propellant lines, feed systems, plume suppression systems and steam ejector trains. While the orifice as a device is largely effective in stepping down pressure, it is also susceptible to a wake-vortex type instability and cavitation instability that propagate downstream and interact with other elements of the test facility resulting in structural vibration. In this proposal a new proprietary instability mitigation device has been developed that steps down the pressure, straightens the flow and suppresses all instability modes. The device is scalable and can be used for different mass flow rates and varying levels of de-pressurization conditions. It is relatively inexpensive to manufacture, easy to fabricate and install, and can be tailored to meet the performance requirements of a given facility. In Phase I, the device has been successfully demonstrated in a sub-scale cryogenic test facility. In Phase II the performance of the device will be calibrated for full-scale operation in a cryogenic test facility and a water test facility.