Performance of a stationary vertical axis vane type rotor tested in a wind tunnel
This paper reports the performance of an equally spaced vertical axis vane type rotor tested in a wind tunnel. The aerodynamic characteristics i.e. torque coefficient, drag coefficient etc. of a stationary vane type rotor have been studied in this research work by measuring the pressure distribution on the blade surfaces at various rotor angles. The experimental investigation was performed on four bladed vertical axis vane type rotor in a uniform flow jet produced by an open circuit wind tunnel. It has been observed that the static torque varies at different rotor angles. Total static torque coefficient at different rotor angles curve repeats from 0° to 80°, 90° to 170°, 180° to 260° and 270° to 350° angle of rotation. A quasi-steady approach was applied for the prediction of dynamic performance of the rotor using the static drag and torque coefficients. This method results in a fair agreement with the measured power coefficient.
Drag and lift
This chapter briefly discusses the external flows. Flow around a body placed in a uniform flow develops a thin layer along the body surface with largely changing velocity, which is the boundary layer, due to the viscosity of the fluid. Furthermore, the flow separates behind the body, discharging a wave with eddies. Whenever a body is placed in a flow, the body is subject to a force from the surrounding fluid. When a flat plate is placed in the flow direction, it is only subject to a force in the downstream direction. Thereafter, a drag is produced because a streamline separates behind a body, develops vortices, and lowers its pressure. Therefore, in order to reduce the drag, it suffices to make the body into a shape from which the flow does not separate. This is called the streamline shape. Of the forces acting on a body placed in a flow, if the body is manufactured as to make the lift larger than the drag, it is called a wing, airfoil, or blade. The shape of a wing section is called an airfoil section.
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.