Calculation of Compressible Subsonic Flow in Cascades With Varying Blade Height

1973 ◽  
Vol 95 (4) ◽  
pp. 345-351 ◽  
Author(s):  
R. A. Van den Braembussche
Keyword(s):  
Experimental Data ◽  
Subsonic Flow ◽  
Rotational Flow ◽  
Blade Surface ◽  
Mixed Flow ◽  
Exact Relation ◽  
Blade Height ◽  
Singularity Method ◽  
Turbine Cascades ◽  
Theoretical Results

This paper deals with a singularity method to calculate the subsonic compressible flow in compressor and turbine cascades, with constant or varying blade height. The method is an extension of an incompressible flow method by means of the Janzen-Rayleigh theorem, using an exact relation between pressure and density. Theoretical results are compared with experimental data. A further extension of this method to rotational flow in plane cascades obtained from the transformation of the blade to blade surface of a mixed flow machine is also discussed.

Numerical Investigation of the Effect of Ash Particle Deposition on the Flow Field Through Turbine Cascades

2002 ◽  
Author(s):  
Hesham El-Batsh ◽  
Hermann Haselbacher
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Pressure Coefficient ◽  
Field Measurements ◽  
Surface Velocity ◽  
Wall Region ◽  
Blade Surface ◽  
Turbine Cascades

Ash deposition on turbine blade surfaces is studied in this work using a particle deposition model. The model involves the three main processes: particle transport to the blade surface particle sticking at the surface and particle detachment from the surface. The model is used to investigate the effect of ash particle deposition on the flow field through turbine cascades. The surface velocity and the downstream total pressure coefficient are calculated for the clean and the fouled blade profiles and used in this investigation. The profile of the clean blade is chosen from the literature for which flow field measurements are available. The two dimensional compressible flow field is solved for the clean blade using the RNG k-ε turbulence model with the two layer zonal model for the near-wall region. The results are compared to the experimental data. The flow field is solved at the conditions expected in modern gas turbines. The deposition distribution on the blade surface is calculated during three periods of 12 operating hours each assuming inlet particle concentration as 100 ppmw. The fouled blade profile is predicted after each period. Then the flow field and deposition calculations are repeated to account for the time-dependent particle deposition. The flow field is calculated for the fouled blade after operating hours and investigated using the experimental data and the numerical calculations of the clean blade. The profile loss of the fouled blade is also predicted and compared to that of the clean blade.

A Study on the Flow Pattern Within the Centrifugal and Mixed-Flow Impellers

1971 ◽  
Author(s):  
Shinpei Mizuki ◽  
Toshimichi Sakai ◽  
Ichiro Watanabe
Keyword(s):  
Experimental Data ◽  
Flow Pattern ◽  
Surface Pressure ◽  
Flow Behavior ◽  
Inviscid Flow ◽  
Flow Patterns ◽  
Blade Surface ◽  
Mixed Flow ◽  
Analytical Results ◽  
Good Coincidence

An Investigation of the flow patterns within the centrifugal and mixed-flow impeller channel were performed. The velocity distributions within the impeller channel and blade surface pressure of the centrifugal and mixed-flow impellers were closely examined by experiment and the flow behavior within these impellers were clarified. The incompressible and inviscid flow within the impellers having straight radial blades were also derived analytically. The present authors assumed an outermost boundary of the relative eddy at the impeller exit periphery and corrected the analytical results. The corrected analytical results thus obtained showed good coincidence with the experimental data.

The Compliance of Solid, Wide-Faced Spur Gears

1990 ◽  
Vol 112 (4) ◽  
pp. 590-595 ◽  
Author(s):  
J. H. Steward
Keyword(s):  
Experimental Data ◽  
Contact Line ◽  
Load Distribution ◽  
3D Model ◽  
Spur Gear ◽  
Point Load ◽  
Spur Gears ◽  
Line Load ◽  
Gear Teeth ◽  
Theoretical Results

In this paper, the requirements for an accurate 3D model of the tooth contact-line load distribution in real spur gears are summarized. The theoretical results (obtained by F.E.M.) for the point load compliance of wide-faced spur gear teeth are set out. These values compare well with experimental data obtained from tests on a large spur gear (18 mm module, 18 teeth).

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

scholarly journals C-VCalculations in CdS/CdTe Thin Films Solar Cells with aCdSxTe1-xInterlayer

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
A. Gonzalez-Cisneros ◽  
F. L. Castillo-Alvarado ◽  
J. Ortiz-Lopez ◽  
G. Contreras-Puente
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Solar Cells ◽  
Photovoltaic Cells ◽  
Cdte Film ◽  
Vapor Transport ◽  
Cdte Solar Cells ◽  
Cdte Thin Films ◽  
Cds Film ◽  
Theoretical Results

In CdS/CdTe solar cells, chemical interdiffusion at the interface gives rise to the formation of an interlayer of the ternary compoundCdSxCdTe1-x. In this work, we evaluate the effects of this interlayer in CdS/CdTe photovoltaic cells in order to improve theoretical results describing experimentalC-V(capacitance versus voltage) characteristics. We extended our previous theoretical methodology developed on the basis of three cardinal equations (Castillo-Alvarado et al., 2010). The present results provide a better fit to experimental data obtained from CdS/CdTe solar cells grown in our laboratory by the chemical bath deposition (for CdS film) and the close-spaced vapor transport (for CdTe film) techniques.

scholarly journals Verification of Brittle Fracture Criteria for Bimaterial Structures

2014 ◽  
Vol 8 (1) ◽  
pp. 44-48
Author(s):  
Grzegorz Mieczkowski ◽  
Krzysztof Molski
Keyword(s):  
Experimental Data ◽  
Composite Materials ◽  
Cyclic Loading ◽  
Brittle Fracture ◽  
Axial Loading ◽  
Loading Conditions ◽  
Fracture Criteria ◽  
Interfacial Cracks ◽  
Theoretical Results ◽  
Brittle Fracture Criteria

Abstract The increasing application of composite materials in the construction of machines causes strong need for modelling and evaluating their strength. There are many well known hypotheses used for homogeneous materials subjected to monotone and cyclic loading conditions, which have been verified experimentally by various authors. These hypotheses should be verified also for composite materials. This paper provides experimental and theoretical results of such verifications for bimaterial structures with interfacial cracks. Three well known fracture hypotheses of: Griffith, McClintock and Novozhilov were chosen. The theoretical critical load values arising from each hypotheses were compared with the experimental data including uni and multi-axial loading conditions. All tests were carried out with using specially prepared specimens of steel and PMMA.

scholarly journals Global Stability and Hopf-bifurcation Analysis of Biological Systems using Delayed Extended Rosenzweig-MacArthur Model

2018 ◽  
Vol 12 (2) ◽  
pp. 171
Author(s):  
Enobong E. Joshua ◽  
Cec Ekemini T. Akpan
Keyword(s):  
Experimental Data ◽  
Population Dynamics ◽  
Hopf Bifurcation ◽  
Asymptotic Stability ◽  
Asymptotically Stable ◽  
Stability Switches ◽  
Large Delay ◽  
Local Hopf Bifurcation ◽  
Delay Margin ◽  
Theoretical Results

This paper investigates the global asymptotic stability of a Delayed Extended Rosenzweig-MacArthur Model via Lyapunov-Krasovskii functionals. Frequency sweeping technique ensures stability switches as the delay parameter increases and passes the critical bifurcating threshold.The model exhibits a local Hopf-bifurcation from asymptotically stable oscillatory behaviors to unstable strange chaotic behaviors dependent of the delay parameter values.Hyper-chaotic fluctuations were observed for large delay values far away from the critical delay margin. Numerical simulations of experimental data obtained via non-dimensionalization have shown the applications of theoretical results in ecological population dynamics.

Part II: Steady aerofoil-spoiler characteristics

1987 ◽  
Vol 91 (908) ◽  
pp. 359-366
Keyword(s):  
Separated Flow ◽  
Experimental Results ◽  
Surface Singularity ◽  
Separation Region ◽  
Two Dimensional ◽  
Trailing Edge ◽  
Singularity Method ◽  
Total Head ◽  
Low Speeds ◽  
Theoretical Results

Summary A surface singularity method has been formulated to predict two-dimensional spoiler characteristics at low speeds. Vorticity singularities are placed on the aerofoil surface, on the spoiler surface, on the upper separation streamline from the spoiler tip and on the lower separation streamline from the aerofoil trailing edge. The separation region is closed downstream by two discrete vortices. The flow inside the separation region is assumed to have uniform total head. The downstream extent of the separated wake is an empirical input. The flows both external and internal to the separated regions are solved. Theoretical results have been obtained for a range of spoiler-aerofoil configurations which compare reasonably with experimental results. The model is deficient in that it predicts a higher compression ahead of the spoiler than obtained in practice. Furthermore, there is a minimum spoiler angle below which a solution is not possible; it is thought that this feature is related to the physical observation that at small spoiler angles, the separated flow from the spoiler reattaches on the aerofoil upper surface ahead of the trailing edge.

scholarly journals LAGRANGIAN BREAKER CHARACTERISTICS FOR NONLINEAR WATER WAVES PROPAGATING ON SLOPING BOTTOMS

2011 ◽  
Vol 1 (32) ◽  
pp. 15
Author(s):  
Yang-Yih Chen ◽  
Meng-Syue Li ◽  
Hung-Chu Hsu ◽  
Ying-Pin Lin
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Empirical Formula ◽  
Wave Breaking ◽  
Present Theory ◽  
Empirical Formulas ◽  
Third Order ◽  
Wave Shoaling ◽  
Theoretical Results ◽  
Sloping Bottom

In this paper, a new third-order Lagrangian asymptotic solution describing nonlinear water wave propagation on the surface of a uniform sloping bottom is presented. The model is formulated in the Lagrangian variables and we use a two-parameter perturbation method to develop a new mathematical derivation. The particle trajectories, wave pressure and Lagrangian velocity potential are obtained as a function of the nonlinear wave steepness  and the bottom slope  perturbed to third order. The analytical solution in Lagrangian form satisfies state of the normal pressure at the free surface. The condition of the conservation of mass flux is examined in detail for the first time. The two important properties in Lagrangian coordinates, Lagrangian wave frequency and Lagrangian mean level, are included in the third-order solution. The solution can also be used to estimate the mean return current for waves progressing over the sloping bottom. The Lagrangian solution untangle the description of the features of wave shoaling in the direction of wave propagation from deep to shallow water, as well as the process of successive deformation of a wave profile and water particle trajectories leading to wave breaking. The proposed model has proved to be capable of a better description of non-linear wave effects than the corresponding approximation of the same order derived by using the Eulerian description. The proposed solution has also been used to determine the wave shoaling process, and the comparisons between the experimental and theoretical results are presented in Fig.1a~1b. In addition, the basic wave-breaking criterion, namely the kinematical Stokes stability condition, has been investigated. The comparisons between the present theory, empirical formula of Goda (2004) and the experiments made by Iwagali et al.(1974), Deo et al.(2003) and Tsai et al.(2005) for the breaking index(Hb/L0) versus the relative water depth(d0/L0) under two different bottom slopes are depicted in Figs 2a~2b. It is found that the theoretical breaking index is well agreement with the experimental results for three bottom slopes. However,for steep slope of 1/3 shown in Fig 2b, the result of Goda‘s empirical formula gives a larger value in comparison with the experimental data and the present theory. Some of empirical formulas presented the breaking wave height in terms of deepwater wave condition, such as in Sunamura (1983) and in Rattanapitikon and Shibayama(2000). Base on the results depicted in Fig. 3a~3b, it showed that the theoretical results are in good agreement with the experimental data (Iwagali et al. 1974, Deo et al.2003 and Tsai et al. 2005) than the empirical formulas. The empirical formula of Sunamura (1983) always predicts an overestimation value.

scholarly journals Effect of Solar Modulation on the Low Energy Sea Level Muon Spectrum Near the Geomagnetic Equator

1978 ◽  
Vol 31 (5) ◽  
pp. 451 ◽  
Author(s):  
DP Bhattacharyya
Keyword(s):  
Experimental Data ◽  
Sea Level ◽  
Low Energy ◽  
Solar Modulation ◽  
Recent Experimental Data ◽  
Geomagnetic Equator ◽  
Muon Spectrum ◽  
Muon Intensity ◽  
Theoretical Results

A study is made of the influence of long-term solar modulation on the low energy sea level muon spectrum near the geomagnetic equator. Recent experimental data are compared with theoretical results calculated from the phenomenological model of Allkofer and Dau. It is suggested that the observed enhancement in the muon intensity is mainly due to a shift in the solar potential.

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