Abstract: Systems and methods are provided for experimentally determining optimized placement and operating conditions, e.g., amplitude, phase, or frequency, of active flow control actuators by executing an optimization routine to sequentially activate varying subsets of active flow control actuators of a plurality of active flow control actuators spatially distributed within a flow field, calculating a cost function of each of the subsets of sequentially activated active flow control actuators based on respective measurements of one or more parameters, e.g., integral variables or proxies to the integral variables, within the flow field by one or more sensors, and determining an optimal subset of active flow control actuators based on the respective cost functions of each of the subsets of sequentially activated active flow control actuators.

Abstract: A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: A centrifugal compressor according to an exemplary aspect of the present disclosure includes, among other things, an impeller provided in a main flow path and configured to pressurize a main flow of fluid. The compressor also includes a secondary flow path configured to provide a secondary flow by recirculating a portion of the main flow. The amount of the main flow that becomes the secondary flow is less than or equal to 15%. A method is also disclosed.

Abstract: A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: A centrifugal compressor according to an exemplary aspect of the present disclosure includes, among other things, an impeller provided in a main flow path and configured to pressurize a main flow of fluid. The compressor also includes a secondary flow path configured to provide a secondary flow by recirculating a portion of the main flow. The amount of the main flow that becomes the secondary flow is less than or equal to 15%. A method is also disclosed.

Abstract: A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: The present invention includes a method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: The present invention includes a method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

Abstract: A system for controlling flow unsteadiness and noise reduction. One or more microjets are placed around the periphery of a jet nozzle in conjunction with a porous surface acting as the impingement surface. As an aircraft is taking off or landing, vertically, the microjets are activated to inject a stream of high-velocity fluid into the shear layer of the main jet at an angle from the main jet centerline. The microjets disrupt the feedback phenomenon, reducing the resonant-dominated aspect of the flow while the porous surface breaks up the coherence of the jet and reduces the broadband noise of the flow.

Abstract: A jet of gas injected from a lance is fluidically deviated with a gas flowing in either the same or opposite direction as the jet of gas. The gas used to fluidically deviate the jet is the same as or different from the gas in the jet.

Abstract: A jet of gas injected from a lance is fluidically deviated with a gas flowing in either the same or opposite direction as the jet of gas. The gas used to fluidically deviate the jet is the same as or different from the gas in the jet.

Abstract: A jet of gas injected from a lance is fluidically deviated with a gas flowing in either the same or opposite direction as the jet of gas. The gas used to fluidically deviate the jet is the same as or different from the gas in the jet.

Abstract: A jet of gas injected from a lance is fluidically deviated with a gas flowing in either the same or opposite direction as the jet of gas. The gas used to fluidically deviate the jet is the same as or different from the gas in the jet.

Abstract: A system for controlling unwanted flow separation. One or more microjets are placed to feed auxiliary fluid into a region of suspected flow separation. If the separation is intermittent, sensors can be employed to detect its onset. Once separation is developing, the microjets are activated to inject a stream of fluid into the separation region. This injected fluid affects the flow and serves to control the flow separation. A steady-state embodiment can be used to continuously fluid. On the other hand, sensors and a rapidly reactive control circuit can be used to inject fluid only when it is needed to inhibit flow separation. The sensors and control circuit can operate off of simple pressure gradient detection or predictive algorithms that anticipate when flow separation will occur.