bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Particles Deposition in Gas Turbine Blades in Presence of Film Cooling
Authors: Borello Domenico , D’Angeli Luca , Salvagni Alessandro , Venturini Paolo , Rispoli Franco 
Published: September 2014

Exhaust entering the gas turbine is usually fed with solid particles produced in the combustion of hydrocarbons (ashes, unburned char, etc.). Then, the interaction between the particles motion and the film cooling jets must be properly addressed.
Here an integrated approach based on an Eulerian-Lagrangian scheme for particle-laden flow was applied to a real turbomachinery case. The code was preliminary assessed by simulating two simplified test cases: a) 3-D cooling jet in a channel; b) 2-D turbine cascade with film cooling. These cases were selected to separately validate the main effects here considered: a) interaction of particles trajectories and 3D cooling jets; b) effect of the cooling jets on surface temperature and particles trajectory and possibly on particle deposition, in comparison with the non-cooled case.
Finally, 3D simulation of the particle-laden flow around a real E3 gas turbine vane with and without film cooling was performed. Flow features, particles trajectories and deposit on the blade are presented.
The compressible flow field was simulated using the OpenFOAM code obtaining credible predictions of the velocity and temperature field.
Then the P-Track code developed by the authors was applied for tracking the particles trajectories and determining the deposit on the solid surface. As the temperature are relatively high, the sticking probability method, that is strongly dependent on the temperature itself, was used here.
The results showed that the presence of the cooling jets affect deeply the deposit following two main causes: the influence of the jets in removing the fluid from the close-to-the-wall region and the reduction of temperature along the blade.
Numerical Analysis and Validation of the Rotor Blade Vibration Response Induced by High Pressure Compressor Deep Surge
Authors: Giersch Thomas , Figaschewsky Felix , Hönisch Peter , Kühhorn Arnold , Schrape Sven 
Published: September 2014

The following paper presents a numerical analysis of a deep surge cycle of a 4.5 stage research compressor. The resulting unsteady loads are used to determine the response of two particular rotor blade rows that are then compared to strain gauge data from measurements. Within a deep surge cycle the compressor experiences a rapid change of the flow field from forward to reversed flow. This rapid breakdown is linked to a new mean blade load. Hence, the rapid change in blade loads are able to excite fundamental blade modes similar to an impulse load. The resulting vibration magnitudes might reach critical levels. This paper demonstrates two different approaches to evaluate the unsteady flow during a surge cycle.
The first uses a three dimensional, time accurate finite volume solver for viscid compressible flows to calculate the transient surge cycle of the compressor. The compressor itself is represented by a multi-blade-row sector model. The second approach makes use of the same solver and compressor domain to determine steady state characteristics of the HPC in forward, stalled and reversed flow. Based on these characteristics an one dimensional finite volume solver for inviscid compressible flows was developed to determine the transient compressor behavior. The one dimensional solver represents the compressor by source terms that are linked to the previously determined steady state characteristics.
Exploitation of Acoustic Effects in Film Cooling
Authors: Collins Matthew , Povey Thomas 
Published: September 2014

There have been numerous studies of the behavior of shaped film cooling holes for turbine applications. It is known that the introduction of coolant is an unsteady process, and a handful of studies have described and characterized the unsteadiness. To the authors’ knowledge there are no studies in which unsteady acoustic effects have been actively exploited such that they have led to novel designs with improved cooling performance.
This paper discusses the fundamental mechanism of pressure wave propagation through cooling holes, and describes systems in which holes which have been acoustically shaped have led to a direct improvement in film cooling hole performance. The mechanism relies on sequential pressure wave reflection within an acoustically shaped hole, and is therefore applicable in regions where the external surface is subject to large pressure wave fluctuations at high frequency. The principle is developed analytically, and then demonstrated with a number of CFD simulations. We demonstrate that a desired temporal mass flow rate profile can be achieved by appropriate acoustic shaping of the cooling hole.
The purpose of this paper is to describe the fundamental design considerations relevant to acoustic shaping. The discussion is developed with reference to a film cooling system for the over-tip region of an un-shrouded rotor. The performance benefit of the system in terms of modulation of unsteady mass flux and ingestion characteristics is quantified. It is believe that this is the first time this significant effect has been exploited in film cooling design.
Experimental and Numerical Investigation of Temperature Fields in a Radial Turbine Wheel
Authors: Diefenthal Mathias , Tadesse Hailu , Rakut Christian , Wirsum Manfred , Heuer Tom 
Published: September 2014

Due to increasing demands on the efficiency of modern Otto and Diesel engines, turbochargers are subjected to higher temperatures. In consequence rotor speed and temperature gradients in transient operations are more severe and therefore thermal and centrifugal stresses increase.
To determine the life cycle of turbochargers more precisely, the exact knowledge of the transient temperature distribution in the turbine wheel is essential.
To assess these temperature distributions, experimental and numerical investigations on a turbocharger of a commercial vehicle were performed. For this purpose, four thermocouples were applied on the shaft and the turbine wheel. The measured temperatures are used to determine the boundary conditions for the numerical calculations and to validate the results.
In the numerical investigations three methods are used to determine and to analyse the transient solid body temperature distribution in respect of the fluid. The methods are compared and evaluated using the measured data. Based on the calculations the transient temperature field is discussed and conclusions concerning to the thermal stresses are drawn.
Blade Design Criteria to Compensate the Flow Curvature Effects in H-Darrieus Wind Turbines
Authors: Balduzzi Francesco , Bianchini Alessandro , Maleci Riccardo , Ferrara Giovanni , Ferrari Lorenzo 
Published: September 2014

Darrieus wind turbines are experiencing a renewed interest in the wind energy scenario, in particular whenever small and medium-size installations are considered. In these contexts, the average wind speeds are generally quite low due to scale effects and therefore the most exploited design choices for the turbines are the H-shape configuration, as the entire blade can take advantage of the maximum rotational radius, and high chord to radius ratios, in order to ensure suitable Reynolds numbers on the airfoils. By doing so, the aerodynamic effects induced by the motion of the airfoils in a curved flowpath become more evident and the airfoils themselves have to be designed to compensate these phenomena if conventional design tools based on the BEM theory are used.
In this study, fully unsteady 2D simulations were exploited to analyze a three-bladed H-Darrieus wind turbine in order to define the real flow structure and its effects on the turbine performance; in detail, the influence of both the virtual camber and the virtual incidence were investigated.
CFD results were supported by experimental data collected on full-scale models reproducing two different airfoil mountings. Finally, the proper design criteria to compensate these phenomena are proposed and their benefits on a conventional simulation with a BEM approach are discussed.
Progress in Smoothed Particle Hydrodynamics to Simulate Bearing Chambers
Authors: Kruisbrink A. Ch. H. , Morvan H. P. , Pearce F. R. 
Published: September 2014

In this paper some novel Smoothed Particle Hydrodynamics (SPH) concepts are presented towards a feasibility study into the use of SPH for some aero-engine applications, e.g. for internal oil or fuel applications.
A first challenge is to develop a capability to model complex wall geometries, associated with two-phase flows in gear boxes and bearing chambers for example. A demonstration is made of how such complex (for SPH) geometries can be built together with an outline of some of the wall boundary condition concepts used, including moving walls. This is an important feature for the application of SPH to engineering. Other boundary conditions are needed such as inlets, outlets and pressure boundaries, and a proper treatment of the free surface. These are outlined in the context of the proposed application.
From an SPH flow simulation viewpoint, one of the challenges is to reduce the non-physical density variations arising from boundary conditions (at wall, free surface and interface), which are responsible for non-physical pressure variations and particle dynamics.
The flow regimes found in the engineering systems outlined above involve droplets, filaments and films. It is therefore important to be able to handle the merging of fluids, as it is to model their interaction with another phase, which calls for appropriate multi-fluid and surface tension models.
This paper introduces SPH, outlines a number of concepts listed above and presents some preliminary results towards the modeling of the KIT bearing chamber, as described by Kurz et al. [1]. This work builds on a number of numerical modeling communications made by the Nottingham team to SPHERIC, the ERCOFTAC Special Interest Group (SIG) for SPH.
Probabilistic Optimization of Two-Phase Flow Using Bayesian Models
Authors: Miki Kenji , Subramaniyan Arun , Pai Madhusudan , Balasubramanyam Preetham 
Published: September 2014

Gas-liquid two-phase flows are encountered in a variety of applications such as turbo-machinery flows, gas-turbines, ram-jet and scram-jets, automotive engines and aircraft engines. Designing systems to control such flows is enormously challenging owing to the addition of new non-dimensional groups that characterize the two-phase flow system compared to a single-phase flow. Additionally, two-phase flows can exhibit non-linear hydrodynamic instabilities that determine the overall behavior of the system.
In this study, we choose a generic two-phase flow configuration that exhibits known complexities in realistic two-phase flow systems. The goal of the study is to optimize the geometry of the two-phase flow configuration with minimal computational cost. We propose a probabilistic approach to model the stochastic system and optimize the two-phase flow system under uncertain inputs. The potential benefits of the approach are highlighted along with future directions for using probabilistic design techniques to optimize two-phase flow systems.
Expander Models for a Generic 300 MW F Class Gas Turbine for IGCC
Authors: Cerri Giovanni , Chennaoui Leila , Giovannelli Ambra , Mazzoni Stefano 
Published: September 2014

Gas Turbines (GTs) for large IGCC plants need some modifications because, usually, they have been developed to be fed with Natural Gas (NG) while the Syngas from the IGCC has a lower Low Heating Value (LHV). As a consequence, the larger flow in the expander raises the compressor exit pressure, producing some instability risks.
One of the possible options consists in the modification of the Expander Flow Functions to accommodate the input pressure in a safe range. The above option modifies also the hot surface blade wall temperature with no changes in cooling flows.
In this paper flow path data, average blade temperatures, cooling flows and global performance for the Reference GT (RGT) fed with CH4 and for the modified GT fed with syngas (H2R-GT) are reported and compared.
The changes in the stagger angles to accommodate the Expander Flow functions for stable GT conditions are presented and results widely discussed.
Numerical Analysis of Gas Turbine Inlet Fogging Nozzle Manifold Pressure Drop
Authors: Zhang Hai , Zheng Qun , Chaker Mustapha , Meher-Homji Cyrus 
Published: September 2014

The air pressure drop over the nozzles manifolds of inlet fogging system and the flow resistance downstream of the nozzle array (manifold) have always been an area of concern and is the object of this paper. Fogging nozzles arrays (involving several hundred nozzles) are mounted on channels and beams, downstream of the inlet filters and affect the pressure drop. The water injection angle, nozzle injection velocities and the progressive evaporation of the water droplets evaporation all influence the inlet pressure seen at the gas turbine inlet. This paper focuses on a numerical simulation investigation of flow resistance (pressure drop) of inlet fogging systems.
In this research effort, the inlet duct is meshed in order to compute the pressure drop over the nozzles frames in fogging and non-fogging conditions. First, the resistance coefficients of an air intake filter are obtained by numerical and experimental methods, and then the coefficients are used for the simulation of the inlet duct by considering the filter as a porous media. Effects of nozzle spread pattern and water injection pattern are then modeled. The results indicate that injection velocity and arrangement of nozzles could have significant effects on the pressure drop and intake distortion, which will affect compressor performance. This paper provides a comprehensive analysis of the pressure drop and evaporation of inlet fogging and will be of value to gas turbine inlet fogging system designers and users.
Prediction of Heat Transfer With Cavity Flow Modeling for Engine Design
Authors: Sasaki Yukie , Hisaeda Koutarou , Matsuno Shinsuke , Nagao Takahisa , Kouwa Junya 
Published: September 2014

In this paper, in order to improve temperature prediction, 2D axisymmetric CFD analysis has been implemented to determine the cavity flow network in Finite Difference Method (FDM) thermal analysis model. With this work process, for example, the complex recirculation of cavity flow can be considered in FDM thermal analysis.
In the beginning, the rig test of simplified cavity with rotating disk and PIV measurement are carried out to investigate the flow structure in the cavity and to validate CFD analysis. CFD result has matched well with the measurement data of PIV, and it has been found that SST k-ω turbulent model provides the most reliable result by the sensitivity study. The study result also helps to choose the most suitable scheme of discretization and the method of pressure correction. Then, the modeling of the cavity flow network based on CFD analysis result has been applied to the thermal analysis for the aero-engine. Compared with the measured data, the result with this modeling shows that temperature prediction has been well improved.
Numerical and Experimental Investigation of Micro-Jet on the Suction Side of a Supersonic Turbine Cascade
Authors: Liu Jian , Qiao Wei-Yang , Huang Peng , Chen Wei-Jie 
Published: September 2014

This paper aims to numerically and experimentally analyze the effect of the micro-jet on the suction side (SS) of the transonic high-pressure turbine cascade, which could enable the possibility of the mass matching for turbine of the variable cycle engine (VCE) when it transforms working conditions according to flight demands. The experimental study had been conducted in a transonic and supersonic cascade wind tunnel to observe the influence of this kind of flow control technique on aerodynamic performance, operated at different exit Mach numbers. The nozzle guide vane with convergent-divergent passage was investigated in this paper. Two-dimensional steady simulations were performed to investigate the influence of the flow control method to exploit the potential of the application of this method in the design of high-pressure (HP) turbine for VCE.
Results of the numerical simulations and experiments indicated that micro-jet on the SS of the turbine blade would generate a separation zone near the jet slot, which would reduce the genuine throat area of the turbine passage and thus change the mass flow rate through the passage of the turbine cascade significantly. Also, velocity at the passage throat would be reduced due to the application of SS micro-jet, which would also contribute to the reduction of the mass flow rate through the turbine passage. However, extended total pressure loss was introduced with SS micro-jet.
A Thermodynamic Evaluation of GTCC/IGCC Based on a Quasi-One-Dimensional Turbine Cooling Model
Authors: Li Zhen , Zhao Lifeng , Wang Bo , Chi Jinling , Zhang Shijie , Xiao Yunhan 
Published: September 2014

Developing an advanced gas turbine (GT) can have a significant impact on the thermodynamic performance of the GT combined cycle (GTCC) and the integrated gasification combined cycle (IGCC). Owing to the importance of system evaluation, it is essential to find ways to accurately predict the performance of state-of-the-art GTs through an accurate and reliable turbine cooling model. Thus, a quasi-one-dimensional (quasi-1D) turbine cooling model, which considers the film cooling and thermal barrier coating (TBC), is established and verified in this work. The model parameters, ηc,∞, ηt,∞, Z, rfc, Bitbc and Tbmx, which represent compressor and turbine efficiencies, convective cooling technology level, film cooling coefficient, Biot number of TBC and allowed maximal temperature of turbine blade, respectively, are confirmed. Reference is made to current advanced GTs during the modeling process. More importantly, the impacts of combustor exit temperature (Tcot), pressure ratio (PR), and cooling approaches on the thermodynamic performance of GTCC are all evaluated based on the quasi-1D turbine cooling model. Results show that the GTCC net efficiency does not always increase along with the increase of Tcot, under the premise of maintaining the cooling technology. The optimal PR, when the GTCC efficiency peaks, exists at each Tcot. In addition, the net efficiency of GTCC, which adopts a closed-loop steam cooling, is improved by about 2 to 3 percentage points compared with that of the conventional open-loop air cooling approach.
Furthermore, the IGCC thermodynamic performance potential is greatly affected by GTCC. It is estimated that the net efficiency of IGCC integrated with 1700 °C-class GT has a total improvement of about 6 percentage points relative to that of IGCC integrated with a GE PG9351FA GT.
The Optimization of an Integrated Strut OGV Configuration
Authors: Xie Yadong , Yang Xiaohe , Ding Jianguo , Liu Xiaofeng , Feng Jinzhang 
Published: September 2014

In a core-mounted high-bypass ratio aero engine the bypass strut is designed to support the intermediate casing and to go the RDF (radial drive shaft) of a large diameter. Therefore the maximum thickness of the strut and maximum thickness distribution along the chord are restricted by the maximum diameter of the RDF.
In order to enhance the total pressure recovery coefficient as well as reducing the backpressure circumferential variation, in this paper we describe the optimization of a datum configuration of the circumferential integrated strut OGV (Outlet Guide Vane).
The datum configuration was designed based on an original configuration in which OGV and struts are separated axially. In the datum configuration, OGV is moved down-stream to be combined with the struts. The combined strut not only supports the casing as discussed above but also plays the role of turning the flow from the upstream fan to the axial direction. At the same time, the maximum thickness of the strut is about 8 times thicker than that of the OGV. The datum configuration will reduce noise because of larger axial distance between fan and OGVs as well as reducing weight because of fewer struts used in datum configuration.
A re-staggering of OGV with sweep and dihedral both at the tip and hub will be used to optimize this datum configuration. Both datum configuration and optimized configuration will be compared with respected to the pressure loss included in the OGV and struts and the backpressure circumferential distribution variation.
Robust Compressor Blades for Desensitizing Operational Tip Clearance Variations
Authors: Seshadri Pranay , Shahpar Shahrokh , Parks Geoffrey T. 
Published: September 2014

Robust design is a multi-objective optimization framework for obtaining designs that perform favorably under uncertainty. In this paper robust design is used to redesign a highly loaded, transonic rotor blade with a desensitized tip clearance. The tip gap is initially assumed to be uncertain from 0.5 to 0.85% span, and characterized by a beta distribution. This uncertainty is then fed to a multi-objective optimizer and iterated upon. For each iteration of the optimizer, 3D-RANS computations for two different tip gaps are carried out. Once the simulations are complete, stochastic collocation is used to generate mean and variance in efficiency values, which form the two optimization objectives.
Two such robust design studies are carried out: one using 3D blade engineering design parameters (axial sweep, tangential lean, re-cambering and skew) and the other utilizing suction and pressure side surface perturbations (with bumps). A design is selected from each Pareto front. These designs are robust: they exhibit a greater mean efficiency and lower variance in efficiency compared to the datum blade. Both robust designs were also observed to have significantly higher aft and reduced fore tip loading. This resulted in a weaker clearance vortex, wall jet and double leakage flow, all of which lead to reduced mixed-out losses. Interestingly, the robust designs did not show an increase in total pressure at the tip. It is believed that this is due to a trade-off between fore-loading the tip and obtaining a favorable total pressure rise and higher mixed-out losses, or aft-loading the tip, obtaining a lower pressure rise and lower mixed-out losses.
Numerical Studies on Application of Blended Blade and Endwall Technique on Transonic Centrifugal Compressor
Authors: Yi Weilin , Chen Zhi-min , Ji Lucheng 
Published: September 2014

With the continuous improvement of pressure ratio and efficiency in centrifugal compressors, the aerodynamic load is increased significantly. Some unnoticed tiny structures are found having notable influence on centrifugal compressor performance, for example, corners profile between the end walls and the blades. Aiming at this problem, the present paper mainly focuses on the applicability of Blended Blade and EndWall (BBEW) design on the transonic centrifugal compressor.
Firstly the Krain transonic impeller is chosen and the predicted flow field is compared with detailed measurement data using commercial CFD code Numeca. The results show that the overall performances are consistent and the details of flow fields are captured accurately. Then a series of uniform value fillets along streamwise are implemented to the hub of transonic centrifugal impeller. The numerical tests show that the aerodynamic performance is deteriorated with the augment of fillets radius, but it seems that adding fillet to the hub of splitter blade can brought positive and negative returns at the same time. Next, as a preliminary original work, a kind of simple Blended Blade and EndWall (BBEW) design which adapt variable radius distribution fillets along streamwise are implemented to the hub of the impeller. Through designing different configurations, the authors find that the performances of some impellers designed by BBEW can be not only higher than impellers with uniform value fillets, but higher than original impeller slightly. In addition, some results are presented on the comparison of flow field structures in different impellers.