Adaptive closed-loop control is used to optimize the lift-to-drag ratio of post-stall separated flow over a NACA 0025 airfoil using multiple amplitudemodulated (AM) or burst-modulated (BM), zero-net-mass-flux (ZNMF) actuators that cover the central 33% span of the airfoil. A simplex optimization approach uses the lift and drag measured by a strain-gauge balance for feedback and searches for the...

Helium pulsed balloons are integral components of several cardiovascular devices, including intraaortic balloon pumps (IABP) and a novel intravenous respiratory support catheter. Effective use of these devices clinically requires full inflation and deflation of the balloon, and improper operating conditions that lead to balloon under-inflation can potentially reduce respiratory or cardiac suppo...

The wind-sensitive cercal system, well-known for mediating terrestrial escape responses, may also mediate insect aerial bat-avoidance responses triggered by wind generated by the approaching bat. One crucial question is whether enough time exists between detection and capture for the insect to perform a successful evasive maneuver. A previous study estimated this time to be 16 ms, based on cock...

Although newer techniques such as laser Doppler and hot-wire anemometry have emerged, aerodynamic probes remain the best tools for the analysis of flows in turbomachines. Based on the nature of how these probes accomplish this analysis, they must be calibrated in well known flows prior to use. This calibration takes place in wind tunnels with uniform, parallel flows at precise Mach numbers. The...

We show that a quantum wire device with spin splitting can work as an active spin polarizer. Hot electrons in one ‘spin’ subband (e.g. ‘spin-up’) may pass such a device with weak electron pair scattering, while electrons in the opposite subband (‘spindown’) may have high conversion probability into the ‘spin-up’ subband, resulting in spin polarization of a hot electron beam. Under different cir...

Absolute measurements of the thermal conductivity of a distilled and dried sample of toluene near saturation are reported. The transient hot-wire technique with an anodized tantalum hot wire was used. The thermal conductivities were measured at temperatures from 300 K to 550 K at different applied power levels to assess the uncertainty with which it is possible to measure liquid thermal conduct...

The ability of a thermal anemometry system to accurately measure unsteady fluid velocity depends on the electrical control system as well as the thermal properties of the sensor. The present work is a numerical study of the thermal transient response of a hot-wire. A conventional constant temperature anemometer with an ideal feedback amplifier as well as a pulse width modulated system were used...

A propulsion system based on acoustic streaming generated by Helmholtz resonators is presented. High frequency (>60 kHz) electrostatically driven micromachined Helmholtz resonators constitute the basic unit of the system. Microjets produced at the exit of these resonators can be combined to form a distributed propulsion system. A high yield (>85%) fabrication process is introduced for fabricati...

A new compact active turbulence generator is developed, tested, and characterized, which extends the capabilities of such generators used in turbulent premixed combustion research. The composed two blades that resemble shape bow-ties. Hot-wire anemometry high-speed imaging are performed to characterize non-reacting flow produced by dynamics, respectively. Two mean bulk velocities 5.0 7.0 m/s ex...

To investigate the feature of turbulence developing behind filter device in a current flow, flow fields at intermediate downstream distance an immersed grid open water channel are recorded using two-dimensional (2D) Particle Image Velocimetry (PIV) system. The measurements on series vertical and horizontal sections conducted to reveal stream-wise evolution depth diversity free surface flow. Unl...