Determination of air and hydrofoil pressure coefficient by laser doppler anemometry

Some results of experiments performed in water cavitation tunnel are presented. Pressure coefficient (Cp) was experimentally determined by Laser Doppler Anemometry (LDA) measurements. Two models were tested: model of airplane G4 (Super Galeb) and hydrofoil of high speed axial pump. These models are not prepared for conventional pressure measurements, so that LDA is applied for Cp determination. Numerical results were obtained using a code for average Navier-Stokes equations solutions. Comparisons between computational and experimental results prove the effectiveness of the LDA. The advantages and disadvantages of LDA application are discussed. Flow visualization was made by air bubbles

The analysis of damage threshold in ruby laser interaction with copper and aluminium

U radu su prikazani rezultati delovanja laserske svetlosti, talasne dužine λ = 694,3 nm (rubinski laser, Q-switch mod), na uzorke od bakra i aluminijuma. Cilj ispitivanja je bio da se odrede maksimalne gustine energije laserskog snopa koje mogu da se koriste u dijagnostičke svrhe (interferometrijska snimanja, lasersko skeniranje, itd), kao i u uklanjanju depozita, a da pri tome snop ne stupa u interakciju sa osnovnim materijalom. Odabrani uzorci od bakra i aluminijuma bili su dugi niz godina izloženi atmosferskim uticajima. Rezultati delovanja laserske svetlosti ispitivani su skenirajućim elektronskim mikroskopom. Istraživanja su pokazala da je bezbedna granica gustine energije rubinskog lasera za dijagnostičke metode za oba metalna uzorka do 20×103 J/m2.Nondestructive methods are dominant in diagnosing the status and protection of all kinds of contemporary industrial objects, as well as objects of industrial heritage. Laser methods open wide possibilities of research in the field of diagnosis and metal processing. This paper presents the results of laser radiation interaction (wavelength λ = 694.3 nm, Ruby laser, Q-switch mode) with metal samples covered with a deposit. The goal of the examination was to determine the maximum energy density of the ruby laser beam, that can be used in diagnostics purposes (interferometric methods; 3D scanning) and as a tool for safe removal of deposits, without interacting with the basic material. Microscopic examination performed with SEM coupled with EDX allowed the determination of the safe laser light energy density levels, which caused the removal of the deposite from the surface of the sample, without degradation of the surface. The energy density up to 20 kJ/m2 is the maximum allowed for diagnosis or deposit removal

Ruby laser beam interaction with ceramic and copper artifacts

Preventive care, research, and restoration of cultural heritage objects requires multidisciplinary research and the involvement of experts of different profiles, using high technology equipment. Nondestructive methods dominate in the diagnosis of the situation and protection of cultural heritage objects. The application of lasers has opened many possibilities for research in the field of protection, conservation, restoration, and/or assessment of artifacts. We present the results of the interaction of ruby-laser light with the surfaces of Neolithic ceramics (Obrenovac, Serbia) and samples of copper of unknown age. The investigation was conducted in order to determine the maximum energy density of the laser light that can be applied in nondestructive testing and encrustation cleaning of these ceramic and metal cultural heritage objects. We investigate the laser-light interactions using a scanning electron microscope (SEM) with energy-dispersal unit for the analysis of X-rays (EDX)

The analysis of damage threshold in the ruby laser interaction with copper and aluminium

Nondestructive methods are dominant in diagnosing the status and protection of all kinds of contemporary industrial object, as well as object of industrial heritage. Laser methods open wide possibilities of research in the field of diagnosis and metal processing. This paper presents the results of laser radiation interaction (wavelength λ = 694.3 nm, Ruby laser, Q-switch mode) with metal samples covered with a deposit. The goal of the examination was to determine the maximum energy density, that can be used in diagnostics purpouses (interferometric methods, 3D scanning, i.e.) and as a tool for safe removal of deposits, without interacting with the basic material. Microscopic examination performed with SEM coupled with EDX allowed the determination of the safe laser light energy density levels, which caused the removal of the deposite from the surface of the sample, without degradation of the surface. The energy density up to 20 103 J/m2 is maximum allowed for the diagnosis or deposit removal