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 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 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 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 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 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 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 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 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 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 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 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 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: An instrumentation system for measuring airspeed and angle-of-attack (AOA) is provided. The system includes a sensor assembly, a constant voltage anemometer, a microprocessor assembly with software, and an output device suitable for powering conventional cockpit display or for powering other speed AOA devices such as engine inlets and stability augmenters. The sensor assembly is a pair of orthogonal miniature cylinders with embedded micro-thin multielement hot film sensors. Operation of the sensor assembly by the constant voltage anemometer provides detection of cylinder leading edge flow stagnation point and oscillatory frequency. The stagnation point determination provides angle-of-attack data; the oscillatory flow frequency provides data to calculate cylinder shed-vortex frequency which is converted to airspeed data. The sensor assembly is solid-state, having no ports, diaphragms or moving parts and is heated in normal operation.

Abstract: A method and portable microcomputer-based system for determining flow field stagnation points are disclosed. The apparatus uses hot film sensors wrapped around the leading edge of an airfoil to measure boundary layer oscillations. A plurality of sensor signals are provided which may be selected in groups. Signals from sensors in any group are read simultaneously. The signals are then converted to digital form and displayed on the video display of a microcomputer. Points of airflow stagnation are characterized by a doubling in frequency or other discrete harmonics and by a reversing of the phase of oscillations. Those points are identified by displaying and comparing signals from different sensor locations on a video display.

Abstract: The invention is a method for measuring the wavelength of cross-flow vortices of air flow having streamlines of flow traveling across a swept airfoil. The method comprises providing a plurality of hot-film sensors. Each hot-film sensor provides a signal which can be processed, and each hot-film sensor is spaced in a straight-line array such that the distance between successive hot-film sensors is less than the wavelength of the cross-flow vortices being measured. The method further comprises determining the direction of travel of the streamlines across the airfoil and positioning the straight-line array of hot film sensors perpendicular to the direction of travel of the streamlines, such that each sensor has a spanwise location.