High Reynolds number tests of a Douglas DLBA 032 airfoil in the Langley 0.3-meter transonic cryogenic tunnel

A wind-tunnel investigation of a Douglas advanced-technology airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (0.3-m TCT). The temperature was varied from 227 K (409 R) to 100 K (180 R) at pressures ranging from about 159 kPa (1.57 atm) to about 514 kPa (5.07 atm). Mach number was varied from 0.50 to 0.78. These variables provided a Reynolds number range (based on airfoil chord) from 6.0 to 30.0 x 10 to the 6th power. This investigation was specifically designed to: (1) test a Douglas airfoil from moderately low to flight-equivalent Reynolds numbers, and (2) evaluate sidewall-boundary-layer effects on transonic airfoil performance characteristics by a systematic variation of Mach number, Reynolds number, and sidewall-boundary-layer removal. Data are included which demonstrate the effects of fixing transition, Mach number, Reynolds number, and sidewall-boundary-layer removal on the aerodynamic characteristics of the airfoil. Also included are remarks on model design and model structural integrity

RF photonic instantaneous frequency measurement using DC photo-detection

A microwave photonic instantaneous frequency measurement (IFM) system based on a photonic transversal approach and DC-detection is proposed and practically demonstrated. This system is able to measure the RF frequency and power level independently

Reduced cost photonic instantaneous frequency measurement system

A wideband photonic instantaneous frequency measurement system is proposed and practically demonstrated. This system employs only a low-frequency inexpensive photodetector and thus the system cost is reduced

Quadrature hybrid coupler using photonic transversal approach

A novel technique to phase shift signal by 90° over a broad frequency range based on transversal signal processing is proposed and practically demonstrated. The proposed technique is suitable for non coherent optic implementation

Two output RF hybrid coupler using photonic transversal approach

A novel technique to implement a two output broad band RF hybrid coupler based on transversal signal processing is proposed and practically demonstrated. It features broadband frequency range, stable phase difference at outputs, 50 ohm input/output impedance, and low noise characteristics. This technique is suitable for non-coherent optic implementation

Amplitude independent RF instantaneous frequency measurement system using photonic Hilbert transform

A photonic instantaneous frequency measurement system capable of measuring both RF frequency and power simultaneously, is conceived and practically demonstrated. This system employs an RF photonic Hilbert transformer together with low-cost, low-frequency photo-detectors to obtain two orthogonal DC measurements. This system exhibits a frequency range of 1-10 GHz. Wider frequency range can be achieved through integration

Wideband RF photonic in-phase and quadrature-phase generation

A photonic implementation of a practical broadband RF Hilbert transformer is demonstrated by using a four-tap transversal system. An almost ideal 90° phase shift with less than 3 dB of amplitude ripple has been achieved from 2.4 to 17.6 GHz. An efficient method to realize both transformed (quadrature-phase) and reference (in-phase) signal has been achieved by using a coarse wavelength division multiplexing coupler. Extension of the transformer bandwidth and further improvements of its implementation are discussed

Photonic instantaneous frequency measurement using non-linear optical mixing

In this paper we propose and demonstrate a photonically implemented instantaneous frequency measurement system. This system uses two differentially delayed modulated optical carriers that are mixed using a semiconductor optical amplifier. The output of the system includes a DC component that varies as a function of frequency. This can be used for frequency measurement using a low-cost DC photo-detector. Operation is demonstrated from 2-20 GHz