bluuebunny/crossref_metadata_2025_split huggingface dataset:
3-D Numerical Simulation of the Flow Through a Turbine Blade Cascade With Cooling Injection at the Leading Edge
Authors: Bohn Dieter , Kusterer Karsten , Schönenborn Harald 
Published: February 2015

High process efficiencies and high power-weight ratios are two major requirements for the economic operation of present day gas turbines. This development leads to extremely high turbine inlet temperatures and adjusted pressure ratios. The permissible hot gas temperature is limited by the material temperature of the blade. Intensive cooling is required to guarantee an economically acceptable life of the components which are in contact with the hot gas. Although film-cooling has been successfully in use for a couple of years along the suction side and pressure side, problems occur in the vicinity of the stagnation point due to high stagnation pressures and opposed momentum fluxes. In this area basic investigations are necessary to achieve a reliable design of the cooled blade.
In the present calculations, a code for the coupled simulation of fluid flow and heat transfer in solid bodies is employed. The numerical scheme works on the basis of an implicit finite volume method combined with a multi-block technique. The full, compressible 3-D Navier-Stokes equations are solved within the fluid region and the Fourier equation for beat conduction is solved within the solid body region. An elliptic grid generator is used for the generation of the structured computational grid, which is a combination of various C-type and H-type grids.
Results of a 3-D numerical simulation of the flow through a turbine blade cascade with and without cooling ejection at the leading edge through two slots are presented. The results are compared with 2-D numerical simulations and experimental results. It is shown that the distribution of the coolant on the blade surface is influenced by secondary flow phenomena which can not be taken into account by the 2-D simulations. Further coupled simulations with non-adiabatic walls in the leading edge region are performed with realistic temperature ratios and compared to the same case with adiabatic walls. It is shown that in the case of non-adiabatic walls the temperature on the blade wall is significantly lower than in the case of adiabatic walls.
Experimental Investigation on Rotating Stall in a Centrifugal Blower With Two and Four Stages and Vaneless Diffusers
Authors: Arnulfi Gianmario L. , Micheli Diego , Pinamonti Piero 
Published: February 2015

The paper presents the results of an experimental investigation on a multistage centrifugal blower, during rotating stall. The test plant allows to change the turbomachine characteristics; in this research the blower has been tested in two different configurations: two-stage and four-stage, with vaneless diffusers.
The unsteady flow field inside the blower has been measured by means of hot-wire anemometers. Three single hot-wire probes have been utilised to measure the development of the rotating stall, while a crossed hot-wire probe has been utilised to obtain the instantaneous flow field behind the impellers.
The measurements have been done at different flow rate values, including stall inception.
Flowfield Measurements for Film-Cooling Holes With Expanded Exits
Authors: Thole K. , Gritsch M. , Schulz A. , Wittig S. 
Published: February 2015

One viable option to improve cooling methods used for gas turbine blades is to optimize the geometry of the film-cooling hole. To optimize that geometry, effects of the hole geometry on the complex jet-in-crossflow interaction need to be understood. This paper presents a comparison of detailed flowfield measurements for three different single, scaled-up, hole geometries all at a blowing ratio and density ratio of unity. The hole geometries include a round hole, a hole with a laterally expanded exit, and a hole with a forward-laterally expanded exit. In addition to the flowfield measurements for expanded cooling hole geometries being unique to the literature, the testing facility used for these measurements was also unique in that both the external mainstream Mach number (Ma∞ = 0.25) and internal coolant supply Mach number (Mac = 0.3) were nearly matched.
Results show that by expanding the exit of the cooling holes, the penetration of the cooling jet as well as the intense shear regions are significantly reduced relative to a round hole. Although the peak turbulence levels for all three hole geometries was nominally the same, the source of that turbulence was different. The peak turbulence level for both expanded holes was located at the exit of the cooling hole resulting from the expansion angle being too large. The peak turbulence level for the round hole was located downstream of the hole exit where the velocity gradients were very large.
Compressible, Turbulent, Viscous Flow Computations for Blade Aerodynamic and Heat Transfer
Authors: Boretti A. A. 
Published: February 2015

The paper presents a computer code for steady and unsteady, three-dimensional, compressible, turbulent, viscous flow simulations. The mathematical model is based on the Favre-averaged Navier-Stokes conservation equations, closed by a statistical model of turbulence. Turbulence effects are represented by using a low Reynolds number K-ω model. The numerical model makes use of a finite difference approximation in generalized coordinates for space discretization. The solution of time-dependent, three-dimensional, non-homogeneous, partial differential equations is obtained by solving, in a prescribed, symmetric pattern, three time-dependent, one-dimensional, homogeneous partial differential equations, representing convection and diffusion along each generalized coordinate direction, and one ordinary differential equation, representing generation and destruction. An explicit, multi-step, dissipative, Runge-Kutta scheme is finally adopted for time discretization.
The code is applied to simulate the flow through a linear cascade of turbine rotor blades, where detailed experimental data are available. Blade aerodynamic and heat transfer are computed, at variable Reynolds and Mach numbers and turbulence levels, and compared with experimental data. While the aerodynamic prediction is relatively unaffected by the properties of both mathematical and numerical models, the heat transfer prediction proves to be extremely sensitive to models details. Low Reynolds number K-ω turbulence models theoretically reproduce laminar, turbulent and transitional boundary layers. However, their practical use in a Navier-Stokes code does not allow to entirely capture the effects of turbulence intensity and Mach and Reynolds numbers on blade heat transfer.
The Path to Predicting Bypass Transition
Authors: Mayle R. E. , Schulz A. 
Published: February 2015

A theory is presented for calculating the fluctuations in a laminar boundary layer when the free stream is turbulent. The kinetic energy equation for these fluctuations is derived and a new mechanism is revealed for their production. A methodology is presented for solving the equation using standard boundary layer computer codes. Solutions of the equation show that the fluctuations grow at first almost linearly with distance and then more slowly as viscous dissipation becomes important. Comparisons of calculated growth rates and kinetic energy profiles with data show good agreement.
In addition, a hypothesis is advanced for the effective forcing frequency and free-stream turbulence level which produce these fluctuations. Finally, a method to calculate the onset of transition is examined and the results compared to data.
Measurements and Prediction of the Effects of Surface Roughness on Profile Losses and Deviation in a Turbine Cascade
Authors: Kind Richard J. , Serjak Peter J. , Abbott Michael W. P. 
Published: February 2015

Measurements of pressure distributions, profile losses and flow deviation were carried out on a planar turbine cascade in incompressible flow to assess the effects of partial roughness coverage of the blade surfaces. Spanwise oriented bands of roughness were placed at various locations on the suction and pressure surfaces of the blades. Roughness height, spacing between roughness elements, and band width were varied.
A computational method based on the inviscid/viscous interaction approach was also developed; its predictions were in good agreement with the experimental results. This indicates that good predictions can be expected for a variety of cascade and roughness configurations from any 2-dimensional analysis which couples an inviscid method with a suitable rough surface boundary-layer analysis. The work also suggests that incorporation of the rough wall skin-friction law into a 3-D Navier-Stokes code would enable good predictions of roughness effects in 3-dimensional situations.
Roughness was found to have little effect on static pressure distribution around the blades and on deviation angle, provided that it does not precipitate substantial flow separation. Roughness on the suction surface can cause large increases in profile losses; roughness height and location of the leading edge of the roughness band are particularly important. Loss increments due to pressure-surface roughness are much smaller than those due to similar roughness on the suction surface.
Comparison of Predicted and Experimental Nusselt Number for a Film-Cooled Rotating Blade
Authors: Garg Vijay K. , Abhari Reza S. 
Published: February 2015

The predictions from a three-dimensional Navier-Stokes code have been compared to the Nusselt number data obtained on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only film-cooled rotating blade over which experimental heat transfer data is available for the present comparison. Over 2.25 million grid points are used to compute the flow over the blade. Usually in a film cooling computation on a stationary blade, the computational domain is just one spanwise pitch of the film-cooling holes, with periodic boundary conditions in the span direction. However, for a rotating blade, the computational domain consists of the entire blade span from hub to tip, as well as the tip clearance region.
As far as the authors are aware of, the present work offers the first comparison of the prediction of surface heat transfer using a three dimensional CFD code with film injection and the measured heat flux on a fully film-cooled rotating transonic turbine blade. In a detailed comparison with the measured data on the suction surface, a reasonably good comparison is obtained, particularly near the hub section. On the pressure surface, however, the comparison between the data and the prediction is poor. A potential reason for the discrepancy on the pressure surface could be the presence of unsteady effects due to stator-rotor interaction in the experiments which are not modeled in the present numerical computations.
Applications of Advanced Liquid Crystal Video Thermography to Turbine Cooling Passage Heat Transfer Measurement
Authors: Campbell Robert P. , Molezzi Michael J. 
Published: February 2015

Over the past few years advances in thermochromic liquid crystal (TLC) thermography have improved its usefulness as a quantitative temperature measurement technique. Many of these improvements have been discussed in the literature but few have been directly applied to solving gas turbine heat transfer problems. The purpose of this work is to combine the best of these techniques into an advanced, easy to use, low cost system which can provide accurate, rapid and complete heat transfer data for advanced gas turbine development.
The older, more common technique of using narrow band liquid crystals to map isotherm distributions has been updated to use wide temperature range crystals with full hue-temperature calibrations over their entire response range with accuracy as good or better than thermocouples. The system consists of an RGB video camera, a hue, saturation and intensity (HS1) framegrabber, on-axis lighting and a linear thermal gradient TLC calibrator. Algorithms have been developed for automated data validation, spatial transformations of data taken on non-planar surfaces and superposition of multiple data sets to construct full field data over surfaces with wide ranges of heat transfer coefficients (h). Instead of yielding mean h, h at a few thermocouple locations or h at individual isotherms, this system provides continuous distributions of h.
These techniques have been used to map the heat transfer coefficient distributions in advanced power generation gas turbine internal cooling passages. These include serpentine passages with and without turbulators, leading edge passages and 180° rums. Results are presented in full field plots of heat transfer enhancement, Nu(x,y)/Nudb.
Effects of Steam Injection and Stochiometry on Cyclone Gasification of Wood Powder
Authors: Fredriksson Christian , Degerman Bengt , Kjellström Björn 
Published: February 2015

Atmospheric gasification of wood powder in a cyclone has been studied. A cyclone gasifier has been designed where the wood powder is injected into the cyclone with air or air/steam as transport media. The effects of stochiometry and steam injection on the gasification temperature and gas composition are investigated. The experimental results are compared with theoretical equilibrium calculations.
The fuel flow has been 26 kg/h corresponding to a thermal input of 140 kW. Equivalence ratio was varied between 0.15 and 0.4. Wood powder has been injected with steam mass flows of 50–80% of the fuel flow. The gas from the cyclone gasifier was analysed regarding CO, H2, CH4 and CO2. The lower heating value of the gas varies between 4 and 6 MJ/Nm3 with lower values for steam injected gasification. Compared to theoretical calculations the air/steam injected measurements showed better agreement with equilibrium predictions than only air injection.
A Unique Approach to HRSG Bypass Dampers
Authors: Ryan David T. , Veatch Judith A. , Pasha Akber 
Published: February 2015

‘Soft’ start flow distribution, control capability, sealing performance, and safety, were four reasons Oklahoma Municipal Power Authority (OMPA), in cooperation with Black & Veatch and Vogt, installed Dual BiPlane Heat Recovery Steam Generator (HRSG) Isolation and Bypass Dampers from Damper Design, Inc. on the gas turbine outlet at this facility.
The DDI BiPlane damper is truly a unique damper for this application. This design allowed OMPA to have the safety and isolation of a flap diverter white providing the even gas distribution and accurate flow control to the HRSG under startup conditions available from a louver style damper.
The arrangement consists of two DDI BiPlane dampers, one on the inlet to the HRSG and one isolating the stack. Since safety is highest priority, Damper Design utilized an independent lockout type linkage that allows control of the dampers while positively preventing the closure of both gas paths at the same time.
By installing the DDI BiPlane damper, OMPA has the ability to throttle the gas turbine exhaust flow independently to the HRSG and stack. This allows the gases to enter the HRSG with a much more evenly distributed flow pattern and at lower controlled flow rates than with competing designs.
This paper will address the benefits, design, and operating advantages of the use of the DDI BiPlane Damper specifically in HRSG isolation and bypass installations. It is also applicable to other systems where control and isolation with one damper is desirable.
Experimental Investigation of Turbulence Structures in the Boundary Layer of a Highly Loaded Turbine Cascade
Authors: Wunderwald Dirk , Fottner Leonhard 
Published: February 2015

An experimental study has been performed on a turbine cascade in order to obtain detailed information about the overall performance, the state of the boundary layer, and the topology of turbulent boundary layers. The analysis of profile pressure distributions and wake traverse measurements across the midspan section of the cascade blade provide information on the loss behaviour. Using surface-mounted hol-film gauges on the suction side of the measuring blade, transition modes have been investigated under the influence of various inlet flow conditions representative of engine operation.
Extensive measurements with 3D-hot-sensor anemometry have been evaluated to show essential features of the turbulent suction side boundary layer. The paper describes the dependence of turbulence characteristics, e.g. integral length scales and turbulent kinetic energy distribution, on the inlet flow conditions and the upstream boundary layer development. The influence of free-stream turbulence intensity and streamline curvature is discussed and the non-isotropy of the Reynolds normal stresses is presented. The evaluation of Reynolds stresses as well as triple order correlations should provide a further insight into the structure of turbulence and lead to a more realistic turbulence modelling.
Dutch Experience With Hot Windbox Repowering
Authors: Ploumen P. J. , Veenema J. J. 
Published: February 2015

The combination of a topping Brayton (gas turbine) cycle with an existing Rankine (boiler-steam turbine) cycle for improved overall cycle heat rate has been very successful in the Netherlands.
In the years 1985–1989 10 gas-fired power plants with a capacity of nearly 4000 MW were substantially modernized by adding a gas turbine topping cycle.
In all these cases the Hot Wind box repowering or Windbox repowering with a supplementary boiler option was chosen.
Besides the improvement of the heat rate it was remarkable that a NOx-emission reduction was achieved between 50 and 85%.
So far more than 500,000 hours experience with hot windbox is available.
If NOx-reduction becomes very important windbox repowering is the best option to modernize power plants.
Predicting Gas Turbine Reliability to Assess Risks for Purchased Power Agreements
Authors: Krockow Wolfram 
Published: February 2015

Availability and Reliability have become a major concern for operating companies; especially for those where unscheduled outages due to purchased power agreements may be highly penalized. On the other hand, high revenues by the sale of electricity can be achieved if the power generating set performs according to its demand.
Economic calculations demonstrate that the bottom line between profit and loss lies within the high 90th% of availability. This paper summarizes the results of an analysis based on the regulations in France with its so-called EJP days (Effacement Jour Pointe). Any loss of highly penalized EJP days is quantified based on known RAM (Reliability, Availability, Maintainability) values of the equipment, as these are the Mean Time Between Failures MTBF’s and the Mean Times To Repair MTTR’s of the overall equipment as well as its subassemblies. In formulating the demand, the past 12 years of assigned EJP days by the Electricité de France, EdF, was analyzed to derive probability ratings of seasonal distributions, weekly distributions and day block distributions.
The mathematics of this simulation model are based on well proven statistical procedures (i.e. the Monte Carlo Method). By performing parameter variations, the model can also quantitatively predict how much the Mean Time Between Failures of a heavy duty gas turbine must usually be better for this application when compared to an aeroderivative gas turbine. This is because it normally takes longer to repair or replace a heavy duty gas turbine versus an aeroderivative unit in case of a major unscheduled or forced outage.
SPE “Mashproekt” Gas Turbine Engines for Gas Pumping Sets
Authors: Romanov Victor I. , Lupandin Vladimir V. , Kovalenko Anatoliy V. , Shelestyuk Anatoliy I. 
Published: February 2015

The paper describes the experience gained in designing, developing and operation of gas turbine engines for gas pumping units on the marine gas turbine engine’s base.
More than 800 Mashproekt gas turbines of various power output have been in service in gas pumping application since 1980.
This paper shows the SPE Mashproekt designing and developing approach for gas turbines to be installed in gas pumping units along with their full-scale testing in the test bed of close gas loop type equipped with gas compressor and gas coolers to simulate operation of the gas pumping unit in the real gas pipeline conditions.
The gas turbines for gas pumping application on the 2.5 MW, 6 MW, 10 MW, 16 MW and 25 MW engines base were developed in the period of 1990–1995 for replacement of the existing old gas turbine line-up and installation in the new gas pumping units at the compressor stations in Russia and Ukraine. We are replacing engines with Mashproekt gas turbines at the following gas pumping units: Russian GTN-25, Ukrainian GPA-6.3, GPA-16 and “Coberra-182” (Great Britain) gas pumping units. The comparison of the technical characteristics of these replacements is given in the paper.
Technical data on 2.5–25 MW Mashproekt gas turbines for gas pumping units is also presented in this paper.
Application of Aeroengine Aerodynamic Design Codes to Industrial Gas Turbine Design
Authors: Little David A. , Cobley Keith 
Published: February 2015

In 1992, Westinghouse Electric Corporation and Rolls-Royce signed a technology transfer agreement. The initial application for this aeroengine technology was the design by Westinghouse of the turbine for the 1500°C turbine inlet temperature, 58% (net) combined cycle efficiency, 501G engine. A key ingredient of the large jump in combined cycle efficiency over that of its predecessor, the 501F, was the reduction in the surface area of the first 3 cooled turbine stages. This reduction was made possible by the application of aerodynamic design and analysis which allowed accurate prediction of suction surface boundary layer growth in a 3D viscous environment. Thus, the number of aerofoils or the aerofoil chords were reduced in each cooled row, until the suction surface boundary layers were predicted to be a specified margin from separation at the trailing edge.
Since the resulting aerofoil loading (back surface diffusion) was higher than previous Westinghouse experience, a 0.32 scale model of a first stage turbine was built and tested in a cold rig at the National Research Council of Canada (NRCC), to substantiate the design codes when applied to industrial turbines. The purpose of the test was threefold: (1) to verify that higher levels of back surface diffusion were possible without boundary layer separation, (2) to verify that aeroengine turbine empirical loss/efficiency prediction correlations were applicable to industrial turbines, and (3) to see how well the single row, 3D, steady, Navier Stokes analysis code used during design predicted actual swallowing capacity, and radial variations in turning and loss.
The paper will describe the aerodynamic design tools and their validation, the test facility, hardware, measurement techniques, test results, and comparisons of prediction vs measurement, thus confirming the applicability of aeroengine aerodynamic technology to the design of large industrial gas turbines.