In the present paper the characterization of the flow field generated by means of a submerged gaseous jet exited by means of a coaxial synthetic jet has been investigated. The purpose of this investigation is to infer the aerodynamic interaction of the two fluid structures that play an interesting role in several industrial applications like jet actuator, flame stability in the combustor for mi...

We report a laser diagnostic technique which relies on planar laser-induced fluorescence of vibrationally excited nitric oxide (NOv 1) molecules produced from the 355 nm photodissociation of seeded NO2 for molecular tagging velocimetry applications. The technique was applied toward an axisymmetric highly underexpanded jet flowfield to yield single-component (streamwise) velocity maps. Detection...

Selective Two-Photon Absorptive Resonance Femtosecond-Laser Electronic-Excitation Tagging (STARFLEET), a non-seeded ultrafast-laser-based velocimetry technique, is demonstrated in reactive and non-reactive flows. STARFLEET is pumped via a two-photon resonance in N2 using 202.25-nm 100-fs light. STARFLEET greatly reduces the per-pulse energy required (30 μJ/pulse) to generate the signature FLEET...

An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Dopp...

A new diagnostic has been developed that is capable of obtaining simultaneous two-phase velocity measurements in a gasoline direct-injection fuel spray. This technique utilizes a two-laser (double-pulse) twocamera (double-frame) setup to simultaneously image the injected fuel and entrained air to determine the 2D velocity vector fields of both phases using cross-correlation particle image veloc...

We present a new particle image correlation technique for resolving nanoparticle flow velocity using confocal laser scanning microscopy (CLSM). The two primary issues that complicate nanoparticle scanning laser image correlation (SLIC)–based velocimetry are (1) the use of diffusion-dominated nanoparticles as flow tracers, which introduce a random decorrelating error into the velocity estimate, ...

Non-destructive measurements by laser Doppler velocimetry is employed to study unsteady flow in a hollow drum filled with liquid. The drum is suddenly accelerated from rest or is suddenly decelerated from a steady rotation to rest. Pure water and glycerin-water mixtures are used as the test liquid in which polyethylenelatex particles are mixed as the light scattering tracer. The boundary layer ...

An experimental method for the determination of the flow-tracing fidelity of a scattering aerosol used in laser Doppler velocimeters was developed with particular reference to the subsonic turbulence measurements. The method employs the measurement of the dynamic response of a flow-seeding aerosol excited by acoustic waves. The amplitude and frequency of excitation were controlled in order to s...

Imaging Laser Doppler Velocimetry (ILDV) is a flow measurement technique which facilitates the measurement of one velocity component of a flow field in an imaging plane. It is an evolution of Heterodyne Doppler Global Velocimetry and may be regarded as the planar extension of the classical dual beam LDV by crossing two light sheets in the flow instead of focused laser beams. With different ligh...

Laser-induced thermal acoustics (LITA) was used with heterodyne detection to measure simultaneously and in a single laser pulse the sound speed and flow velocity of NO>(2) -seeded air in a low-speed wind tunnel up to Mach number M =0.1 . The uncertainties of the velocity and the sound speed measurements were ~0.2 m/s and 0.5%, respectively. Measurements were obtained through a nonlinear least-s...