Abstract: A method is provided for determining flow conditions for a body immersed in a fluid. The method comprises obtaining flow sensor data downstream of the leading edge stagnation point (LESP) using one or more minimal calibration flow sensors. The method further comprises obtaining at least one normalizing flow parameter value and normalizing the flow sensor data using the at least one normalizing flow parameter value. The method also comprises determining an overall flow condition for the body using the normalized flow sensor data.

Abstract: A flow speed sensor arrangement is provided for measuring a flow speed of a fluid stream relative to an object. The arrangement comprises a first obstructive body having a first forward facing surface and two lateral edges and a second obstructive body having a second forward facing surface. The second obstructive body is positioned in tandem relative to the first obstructive body so that the first and second forward facing surfaces face the same direction and so that when the first forward facing surface is presented to an incoming fluid stream, the first obstructive body is between the incoming fluid flow and the second obstructive body. A sensor array is disposed on the second forward facing surface. The first and second obstructive bodies are attachable to the object so that the first forward face is presented to an incoming fluid stream when the object is immersed in the fluid stream.

Abstract: A flow speed sensor arrangement is provided for measuring a flow speed of a fluid stream relative to an object. The arrangement comprises a first obstructive body having a first forward facing surface and two lateral edges and a second obstructive body having a second forward facing surface. The second obstructive body is positioned in tandem relative to the first obstructive body so that the first and second forward facing surfaces face the same direction and so that when the first forward facing surface is presented to an incoming fluid stream, the first obstructive body is between the incoming fluid flow and the second obstructive body. A sensor array is disposed on the second forward facing surface. The first and second obstructive bodies are attachable to the object so that the first forward face is presented to an incoming fluid stream when the object is immersed in the fluid stream.

Abstract: A method is provided for calculating flow performance characteristics of a body immersed in a fluid under a set of fluid flow conditions. The method comprises providing a geometrical description of a surface of the body and determining the set of fluid flow conditions. The set of fluid flow conditions includes a combination selected from the combination set consisting of angle of attack and leading edge stagnation point location, angle of attack and flow separation point location, and leading edge stagnation point location and flow separation point location. The method further comprises calculating a velocity flow field for the body using a critical point potential flow methodology and calculating flow performance characteristics.

Abstract: A system is provided for control of a structure immersed in a fluid flow regime. The system comprises a plurality of flow sensors disposed on a surface of the structure, the flow sensors including at least one flow bifurcation point sensor. The system further comprises at least one structural sensor attached to the structure for measurement of a structural parameter. A data processor in communication with the flow sensors and the at least one structural sensor is configured for processing the data signals and for generating and transmitting one or more actuator command signals to effect a desired flow and structural state for the structure. The system also comprises at least one actuator in communication with the data processor.

Abstract: A temperature compensating fluid flow sensing system is provided that comprises a resistance-based sensor element that is included in a constant voltage anemometer circuit configured to establish and maintain a command voltage across the first sensor element and to provide a constant voltage anemometer (CVA) output voltage corresponding to the resistance change in the first sensor element due to heat transfer between the first sensor element and the fluid. A controller is configured to establish the command voltage based on a desired overheat across the sensor and an actual overheat across the first sensor element. A power dissipation (PDR) module is configured to determine at least one fluid flow parameter and an actual overheat value based at least in part on the CVA output voltage and to transmit to the controller the actual overheat for use by the controller in updating the command voltage.

Abstract: A system is provided for controlling boundary layer shear stress adjacent a surface over which a fluid stream has been established. The system comprises a boundary layer control device adapted for altering at least one flow characteristic within a boundary layer in a selected region of the surface. The system further comprises a shear stress measurement system comprising a hot film sensor arrangement having at least one hot film sensor element appliable to the surface in the selected region. The at least one hot film sensor element is connected to an anemometer circuit configured to provide a sensor signal corresponding to heat transfer from the associated hot film sensor to the fluid stream. The system also comprises a control module in communication with the anemometer arrangement and the boundary layer control device. The control module is adapted for receiving and processing sensor signals signal from the anemometer circuit and for providing input signals to the boundary layer control device.

Abstract: A sensor circuit is provided that includes at least one pair of interconnected T-networks. Each pair has a first T-network including a first impedance serially connected to second impedance at a first junction and a first variable resistance sensor element connected to the first junction. Each pair also has a second T-network including a third impedance serially connected to a fourth impedance at a second junction and a second variable resistance sensor element connected to the second junction. The sensor circuit further includes an operational amplifier connected to the first T-network of a selected one of the at least one pair of T-networks and a constant voltage source connected to the second T-network of the selected T-network pair.

Abstract: A sensor circuit is provided that comprises at least one pair of interconnected T-networks. Each pair comprises a first T-network including a first impedance serially connected to a second impedance at a first junction and a first variable resistance sensor element connected to the first junction. Each pair also comprises a second T-network including a third impedance serially connected to a fourth impedance at a second junction and a second variable resistance sensor element connected to the second junction. The sensor circuit further comprises an operational amplifier connected to the first T-network of a selected one of the at least one pair of T-networks and a constant voltage source connected to the second T-network of the selected T-network pair.

Abstract: A sensor circuit is provided that includes a first T-network including a first impedance serially connected to a second impedance at a first junction and a first variable resistance sensor element connected at a first end to the first junction and at a second end to ground. The sensor circuit also includes a second T-network including a third impedance serially connected to a fourth impedance at a third junction and a second variable resistance sensor element having first and second sensor element ends. The first sensor element end is connected to the third junction and the fourth impedance is connected to the second junction. The sensor circuit further includes a constant voltage source connected to the third impedance and to ground. The second end of the second variable resistance sensor element is connected to a fourth junction intermediate the constant voltage source and ground.

Abstract: A method for locating two dimensional critical flow features on a surface of a three dimensional body immersed in a fluid stream is presented. The method includes applying a hot film sensor array on the surface of the body. The hot film sensor array includes a plurality of hot film sensor elements disposable in a two dimensional array over at least a portion of the body surface. Each sensor element is connected to an associated anemometer circuit to provide an output voltage. The method further comprises obtaining output voltage data for each hot film sensor element with the body immersed in the fluid stream under a set of flow conditions and processing the hot film sensor element output voltage data to locate at least one two dimensional critical flow feature on the body surface.

Abstract: A method for locating two dimensional critical flow features on a surface of a three dimensional body immersed in a fluid stream is presented. The method comprises applying a hot film sensor array on the surface of the body. The hot film sensor array comprises a plurality of hot film sensor elements disposable in a two dimensional array over at least a portion of the body surface. Each sensor element is connected to an associated anemometer circuit to provide an output voltage. The method further comprises obtaining output voltage data for each hot film sensor element with the body immersed in the fluid stream under a set of flow conditions and processing the hot film sensor element output voltage data to locate at least one two dimensional critical flow feature on the body surface.

Abstract: A method is provided for determining a load on an object immersed in a fluid stream under a set of flow and attitude conditions associated with unsteady flow phenomena. The method comprises measuring surface heat transfer at a plurality of surface locations on the object under the flow and attitude conditions to provide a set of heat transfer data. The heat transfer data are used to determine an indicator surface location of at least one critical flow feature indicator. The method further comprises calculating a load coefficient using the indicator surface location of the at least one critical flow feature indicator and calculating the load from the load coefficient and the flow and attitude conditions.

Abstract: A method is provided for detecting flow bifurcation during sonic flow conditions to identify shock location. The method includes setting the initial test conditions, either by setting up an altitude and airspeed in a test aircraft or by setting up an initial flow condition in a wind tunnel. The method for detecting flow bifurcation during sonic flow conditions to identify shock location requires an array of hot films be attached to an aerodynamic surface where shock is expected to impinge. These hot-films are connected to a bank of Constant Voltage Anemometers (CVA), one CVA for each hot film. After reaching the altitude where the testing is to be done, (or attaining the reference condition in a wind tunnel), a pilot initiates an auto-initializing sequence before the onset of a shock, typically at a low speed condition. This sets the current in each sensor to identical values and sets the sensor temperature above ambient temperature of the reference conditions.

Abstract: Arrays of microslats operating within the boundary layer of an aircraft wing or other surfaces are provided. The arrays consist of rows of microslats, staggered between rows, and shaped so that the trailing edge of the microslat is normal or perpendicular to the direction of expected reverse flow on the surface. For flow regions having directionally stable flow, the microslats are rectangular. Where the direction of the expected reverse flow is variable, the trailing edge of the microslats is triangular, thereby accepting an angular range of reverse flow. Each microslat operates independently through a hinge on its leading edge and an individual spring which holds the microslat flush to the aerodynamic surface until actuated by reverse flow. Where the boundary layer is expected to thicken, i.e., downstream along a surface, the arrays are formed with two layers of microslats, smaller microslats in a top layer and larger in a bottom layer.

Abstract: A broad-range, multi-directional aircraft airspeed measuring system is provided. The airspeed measuring system has multiple vortex generating probes located within a venturi section. At least one rearward facing probe and one forward facing probe are included. Additional probes can be added to extend the high speed range of the airspeed indicator. A splitter plate or plates separate flow channels from each other to provide a separate flow channel for each vortex probe. Each vortex probe has a hot film sensor and anemometer.

Abstract: A method for compensating for the time constant (delay time) of hot-wire/hot-film in a constant voltage anemometer is provided. The method is a two-part series of steps, the first series for measuring the time constant in a particular wind tunnel setup and a second series for compensating for the measured time constant. The first series or measuring steps include setting up a hot-wire/hot film for a particular test at a specific operating point. A step increase in sensor current is applied and the resistance change of the sensor is measured. The time to reach 63% of the final resistance value is recorded. (The time constant is defined as the time to reach 63% of the resistance value). The measured time constant value is used to match the time constant in the CVA circuit.