bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Mistuning for Casted Turbine Wheels of Small Size
Authors: Hemberger David , Filsinger Dietmar , Bauer Hans-Jörg 
Published: September 2014

The production of bladed structures, e.g. turbine and compressor wheels, is a subject of statistical scatter. The blades are designed to be identical but differ due to small manufacturing tolerances. The manufacturing tolerances may lead to difference in shape, mass and stiffness distribution of the turbine blades. But it can also take effect on in-homogeneities in the material, which are caused by the casting process and can, for example, reflect in residual stresses and grain size differences. These properties can lead to so called mistuning that increases vibration amplitudes compared to the ideal tuned case, which can end in critical vibration conditions.
The object of this study is to determine the main source of mistuning for casted turbine wheels in automotive turbocharger applications. The authors have shown in context of a study on mistuning modeling for turbine wheels in automotive turbochargers, that the mistuning due to the geometrical deviation of the shape is not necessarily solely the main mistuning source.
To examine this, various numerical models were evaluated, but also measurements during operation and standstill condition were carried out. Casted turbine wheels with different grain structures and also milled turbine wheels from forged round blanks were analyzed. Besides these, FE-models from casting simulations were used to analyze residual stress and material property effects on mistuning.
For the milled turbine wheels the source of the mistuning could be assigned to the deviation of the blade shape. The source of mistuning for the casted turbine wheels, however, could be attributed to the material in-homogeneity.
Efficient Rotating Frame Simulation in Turbomachinery
Authors: Remaki L. , Ramezani A. , Blanco J. M. , Antolin J. I. 
Published: September 2014

This paper deals with the simulation of steady flows in turbomachinery. Two approaches are proposed, the first one is the classical multiple-rotating frame method (MRF) by multi-zone approach where the different zones are separated by non-overlapping interfaces and solved independently. Since each zone is loaded separately, a transferring system should be properly implemented at the interface boundaries. Two techniques are considered, in the first one the conservative variables are interpolated between zones while in the second one the fluxes are transferred through the interfaces.
The other proposed approach is a new version of the MRF using a virtual interface (VMRF). This is a simplified of the previous one where the interfaces are created virtually at the solver level, rendering the method easy to implement especially for edge-based numerical schemes, and avoiding any re-meshing in case one needs to change interface position, shape or simply remove or add new one. Finally, numerical tests are performed to demonstrate the efficiency of the proposed methods by comparison with commercial codes (ANSYS FLUENT).
Application of an Analytical Method to Locate a Mixing Plane in a Supersonic Compressor
Authors: Benichou E. , Trébinjac I. 
Published: September 2014

In order to achieve greater pressure ratios, compressor designers have the opportunity to use transonic configurations. In the supersonic part of the incoming flow, shock waves appear in the front part of the blades and propagate in the upstream direction.
In case of multiple blade rows, steady simulations have to impose an azimutal averaging (mixing plane) which prevents these shock waves to extend upstream. In the present paper, several mixing plane locations are numerically tested and compared in a supersonic configuration.
An analytical method is used to describe the shock pattern. It enables to take a critical look at the CFD steady results. Based on this method, the shock losses are also evaluated. The good agreement between analytical and numerical values shows that this method can be useful to wisely forecast the mixing plane location and to evaluate the shift in performances due to the presence of the mixing plane.
Fuel Influence on Targeted Gas Turbine Combustion Properties: Part II — Detailed Results
Authors: Burger Victor , Yates Andy , Mosbach Thomas , Gunasekaran Barani 
Published: September 2014

The paper presents the results from a study that formed part of a bilateral project between DLR-VT and Sasol Technology Fuels Research aimed at investigating the potential influence of physical and chemical fuel properties on ignition and extinction limits within heterogeneous gas turbine combustion. The threshold of flame extinction and re-ignition behaviour of a range of alternative fuels was investigated in a representative aero-combustor sector to determine the relative influence of physical properties and chemical reaction timescales.
A matrix of eight test fuels was selected for use during the study and included conventional crude-derived Jet A-1, synthetic paraffinic kerosene, linear paraffinic solvents, aromatic solvents and pure compounds. All test fuels were characterised through full specification analyses, distillation profiles and two-dimensional gas chromatography.
The ignition and extinction behaviour of the test fuel matrix was evaluated under simulated altitude conditions at the Rolls-Royce Strategic Research Centre’s sub-atmospheric altitude ignition facility in Derby, UK. A twin sector segment of a Rich Quench Lean (RQL) combustor was employed with fuel supplied to a single burner. Combustor air inlet conditions were controlled to 41.4 kPa and 265 K. Fuel temperature was controlled to 288 K.
In addition to the standard extinction and ignition detection systems, optical diagnostics were applied during the test programme. Simultaneous high-speed imaging of the OH* chemiluminescence, and broadband flame luminosity was employed to capture the main reaction zones, the global heat release and distribution of radiative soot particles respectively.
Lean extinction points were determined using both a photodiode as well as from the OH* chemiluminescence data. The position of extinction and overall combustor ignition and extinction timescales were determined. The diagnostic methodology that was used to obtain the results reported in this paper is discussed in greater detail in a separate complementary paper.
All eight fuels, including the fully synthetic Jet A-1 fuels that formed part of the test matrix, yielded performance that was comparable to that obtained with conventional crude-derived Jet A-1.
Modernization of the Equipment of a Head Compressor Station
Authors: Janßen Stefan , Pätzold Peter , Emde Axel , Kurz Rainer 
Published: September 2014

The Waidhaus compressor station in Germany is a key compressor station for the supply of Natural Gas from Russia into the German and the European market. The required flexibility, together with the goal of a small environmental footprint, has led to some unique, but widely applicable solutions. Since this head compressor station of the MEGAL pipeline system is of highest importance for the European gas supply, requirements for high availability and reliability of the equipment are significant. The paper consists of two parts: In the first part it describes the challenges of installing new equipment in an existing compressor station, details the characteristics of the installed equipment, and, in particular, discusses the steps that have been taken to assure the required high availability, high reliability, and high flexibility. In the second part, the acceptance test is described, taking into account site specific limitations, and how a highly accurate site test can be executed. The tested unit was accepted based on the acceptance test described. The methodology is useful for the conduct and execution of site performance tests.
The paper thus provides insight into the decision making, installation, and acceptance process for the specific situation of a strategically important brownfield compressor station.
New Single Crystal Superalloys, CMSX®-8 and CMSX®-7
Authors: Wahl Jacqueline B. , Harris Ken 
Published: September 2014

Single crystal (SX) superalloys have wide application in the high pressure turbine section of aero and industrial gas turbine engines due to the unique combination of properties and performance. Since introduction of single crystal casting technology, SX alloy development has focused on increased temperature capability, and major improvements in alloy performance have been associated with the introduction of new alloying elements, including rhenium (Re) and ruthenium (Ru). 3% Re-containing second generation alloys, such as CMSX-4®, PWA 1484 and Rene’ N5 have seen the greatest market utilization and have become the benchmark alloys for comparing new alloy developments. However, Re and Ru are rare elements with limited production/availability and corresponding high costs. This has resulted in significant escalation of SX alloy costs, and consequently, there has been much interest in the development of improved SX superalloys with lower Re or no Re content compared to second generation alloys.
Cannon-Muskegon® has developed two new SX superalloys: 1.5% Re CMSX®−8 alloy and CMSX®−7 alloy, which contains no Re, as alternatives to first and second generation alloys for applications which require slightly less ultra high temperature capability compared to CMSX-4 alloy or the improved CMSX-4(SLS) alloy. This paper provides an overview of development and characterization of these SX alloys and alloy modifications, CMSX-8 (SLS) and CMSX-8[B/C](SLS).
Effect of Channel Orientation on Heat Transfer in Rotating Smooth Square U-Duct at High Rotation Number
Authors: Li Yang , Deng Hongwu , Xu Guoqiang , Qiu Lu , Tian Shuqing 
Published: September 2014

The effect of channel orientation on heat transfer in a rotating, two-pass, square channel is experimentally investigated in current work. The classical copper plate technique is employed to measure the regional averaged heat transfer coefficients. The inlet Reynolds number and Rotation number range from 25000 to 35000 and 0 to 0.82, respectively. Five different channel angles (−45°, −22.5°, 0°, 22.5°, 45°) are selected to study the effect of channel orientation on heat transfer.
In the radially outward flow channel, the surface average heat transfer in β = 0° channel are higher than those in angled-channel (±22.5°, ±45°) on the trailing surface at all Rotation number ranges (0–0.82). While on the leading surface, surface average heat transfer are lower before a critical Rotation number, and turn higher after the critical point. Channel orientations show less influence on heat transfer in the radially inward flow channel.
Compared with their corresponding perpendicular channel orientation values (β = 0° channel), heat transfer in angled-channels decrease on the pressure side and increase on the suction side at a relatively lower Rotation number (Ro<0.4) for both inward and outward channels. While at higher Rotation number (Ro>0.4), heat transfer in angled-channel decrease on both the leading and trailing walls in the first pass, and increase on both the leading and trailing walls in the second pass. By considering the effect of channel orientations, the relation between critical Rotation number on the leading surface in the first pass and dimensionless location (X/D) obeys a simple rule: (Roc·X/D)·cosβ = 1.31. The trailing-to-leading heat transfer differences induced by rotation increase with the increasing of Rotation number in angled-channel, and they are larger than β = 0° channel after the critical Rotation number in both passages.
Film Cooling Modeling of Turbine Blades Using Algebraic Anisotropic Turbulence Models
Authors: Li Xueying , Ren Jing , Jiang Hongde 
Published: September 2014

The complex structures in the flow field of gas turbine film cooling increase the anisotropy of turbulence making it difficult to accurately compute turbulent eddy viscosity and scalar diffusivity.
An algebraic anisotropic turbulence model is developed while aiming at a more accurate modeling of the Reynolds stress and turbulent scalar flux. In this study the algebraic anisotropic model is validated by two in-house experiments. One is a leading edge with showerhead film cooling and the other is a vane with full coverage film cooling. Adiabatic film cooling effectiveness under different blowing ratios, density ratios and film cooling arrangements were measured using PSP technique. Four different turbulence models are tested and detailed analyses of computational simulations are performed.
Among all the turbulence models investigated, the algebraic anisotropic model shows better agreement with the experimental data qualitatively and quantitatively. The algebraic anisotropic model gives a good prediction of the vortex strength and turbulence mixing of the jet, therefore improves the prediction of the scalar field.
Gas Turbine Plant With Overexpansion Turbine and Heat Regeneration in the Ship Propulsion Complex
Authors: Matviienko V. , Andriets O. , Ocheretianyi V. 
Published: September 2014

Gas turbine engines (GTE) are widely applied in the ship propulsion complexes. Although GTE have many technical advantages, but for the wider application in shipbuilding it is necessary to carry out one of the most important requirements that nowadays is actual for all power-engineering objects — to increase efficiency of their operating.
This problem is solved by GTE Complex Cycle together with the utilization of the exhaust gases heat. At present a non-traditional method of GTE cycle complication is an application of overexpansion turbine, which with the exhaust compressor and gas cooler between them forms turbo-compressor utilizer (TCU). In the overexpansion turbine is used internal energy of the exhaust gases, that allows to get (after deduction of energy expenditure for pressing out of gas) an additional useful work that increases engine efficiency. The tests results on experimental co-generative gas turbine plant with TCU confirmed the trustworthiness of theoretical elaboration of the operating GTE with the overexpansion turbine.
When gas is being cooled after the overexpansion turbine the portion of taken heat can be used to heat air pressed in the GTE compressor in recuperator before the combustion chamber. Hereby the heat utilization of exhaust gases inside GTE cycle is carried out, that ensures additional increasing of the engine efficiency.
Gas cooler in TCU is used as an utility boiler for the supply of heating power to ship’s consumers and other technological consumers. In that way GTE with TCU including recuperator is the co-generative plant. The applying of GTE with TCU including recuperator on the oil-tankers provides ship’s propulsion as well as the heating of oil transported in tanks, that allows GTE to reach high energy efficiency on the whole ship power plant.
Geometrical Optimization and Experimental Validation of a Tripod Film Cooling Hole With Asymmetric Side Holes
Authors: Chi Zhongran , Han Chang , Li Xueying , Ren Jing , Jiang Hongde 
Published: September 2014

A tripod cylindrical film hole with asymmetric side holes is studied numerically and experimentally on a flat plate for higher film cooling effectiveness. Firstly, the influences of geometrical parameters are studied and the optimum configurations of the asymmetric tripod hole are found in a DoE optimization study based on an improved numerical model for film cooling prediction, in which more than one hundred 3D CFD simulations are carried out. Then one optimum configuration of the asymmetric tripod hole is examined experimentally using pressure-sensitive paint (PSP) measurements, and compared against the experimental results of the simple cylindrical film hole and a well-designed shaped film hole.
The flow and heat transfer characteristics of the asymmetric tripod holes were explored from the DoE results. The side holes can form a shear vortex system or an anti-kidney vortex system when proper spanwise distances of them are adopted, which laterally transports the coolant and form a favorable coolant coverage. According to the experimental results, the cooling performance of the optimized asymmetric tripod hole is significantly better than that of the simple cylindrical hole, especially at high blowing ratios. And the optimized asymmetric tripod hole can provide almost the same or even higher film cooling effectiveness on the flat plate compared with the shaped hole in the same flow conditions.
Experimental Analysis of Dynamic Interaction Between a Centrifugal Compressor and its Casing
Authors: Almeida P. , Gibert C. , Thouverez F. , Leblanc X. , Ousty J.-P. 
Published: September 2014

In turbomachinery, one way to improve aerodynamic performance and reduce fuel consumption consists of minimizing the clearance between rotor and casing. Yet the probability of contact is increased and this may lead in some specific conditions to a large and even unstable excitation on the impeller and stator. To achieve better understanding of the dynamic behavior occurring during the blade-to-casing contact, many numerical studies have been conducted but only a few experiments have been reported in the literature thus far.
The interaction experiment reported in this paper involves a low-pressure, rotating centrifugal compressor and its casing tested in a vacuum chamber. Contact is initiated by introducing a gap near zero, and certain events with significant dynamic levels are observed during the run-up. Measurements are performed using strain gauges on both the rotating and stationary parts and a Scanning Laser Doppler Vibrometer on the stator. This research focuses on an analysis of the recorded data. Time series data are also analyzed by means of standard signal processing and a full spectrum analysis in order to identify the direction of traveling wave propagation on the two structures as well as nodal diameters and frequencies.
The dynamic response of structures is accompanied by variations in other physical parameters such as temperature, static deformed shapes, speed and torque. A wearing pattern is evaluated following the contact experiments. The spectral content of response is dominated by frequency modes excited by engine orders as well as by sidebands due to inherent system non-linearity.
Stress–Strain State Prediction of High-Temperature Turbine Single Crystal Blades Using Developed Plasticity and Creep Models
Authors: Vasilyev Boris 
Published: September 2014

This paper discusses a novel approach to calculating inelastic strain that incorporates elastic anisotropy in combination with ANSYS finite element analysis (FEA) software to predict the stress–strain state kinetics of a single crystal (SX) nickel-based turbine blade. The approach is based on using “equivalent direction” and allows us to correctly define the critical load value and plastic strain field in SX details for different load types. The suggested approach is simple and generic and requires only a few standard experimental material properties. This should allow for an easy transition to actual blade design application.
Predictions of plastic field distribution obtained using the suggested approach with anisotropic specimens are compared with experimental data as well as with the results obtained using a crystallographic approach. Good correlation was achieved.
The second goal of this study is to develop a physically based, readily implementable creep model SX superalloy that accurately represents the creep phenomena of these materials under complex, thermomechanical loading conditions.
Accurate Radial Vaneless Diffuser 1D Model
Authors: De Bellis Fabio , Grimaldi Angelo , Rubino Dante Tommaso , Amirante Riccardo , Distaso Elia 
Published: September 2014

A simplified one dimensional model for the performance estimation of vaneless radial diffusers is presented. The starting point of such a model is that angular momentum losses occurring in vaneless diffusers are usually neglected in the most common turbomachinery textbooks: it is assumed that the angular momentum is conserved inside a vaneless diffuser, although a non-isentropic pressure transformation is considered at the same time. This means that fluid-dynamic losses are taken into account only for what concerns pressure recovery, whereas the evaluation of the outlet tangential velocity incoherently follows an ideal behavior.
Several attempts were presented in the past in order to consider the loss of angular momentum, mainly solving a full set of differential equations based on the various developments of the initial work by Stanitz. However, such formulations are significantly more complex and are based on two empirical or calibration coefficients (skin friction coefficient and dissipation or turbulent mixing loss coefficient) which need to be properly assessed.
In the present paper, a 1D model for diffuser losses computation is derived considering a single loss coefficient and without the need of solving a set of differential equations. The model has been validated against massive industrial experimental campaigns, in which several diffuser geometries and operating conditions have been considered. The obtained results confirm the reliability of the proposed approach, able to predict the diffuser performance with negligible drop of accuracy in comparison with more sophisticated techniques. Both preliminary industrial designs and experimental evaluations of the diffusers may benefit from the proposed model.
Pressurized SOFC Hybrid Systems: Control System Study and Experimental Verification
Authors: Larosa Luca , Traverso Alberto , Ferrari Mario L. , Zaccaria Valentina 
Published: September 2014

In this paper two different advanced control approaches for a pressurized SOFC hybrid system are investigated and compared against traditional proportional–integral–derivative (PID). Both advanced control methods use model predictive control (MPC): in the first case, the MPC has direct access to the plant manipulated variables, in the second case the MPC operates on the setpoints of PIDs which control the plant. In the second approach the idea is to use MPC at the highest level of the plant control system to optimize the performance of bottoming PIDs, retaining system stability and operator confidence. Two MIMO (multi-input multi-output) controllers were obtained: fuel cell power and cathode inlet temperature are the controlled variables; fuel cell by-pass flow, current and fuel mass flow rate (the utilization factor kept constant) are the manipulated variables.
The two advanced control methods were tested and compared against the conventional PID approach using a SOFC hybrid system model. Then, the MPC controller was implemented in the hybrid system emulator test rig developed by the Thermochemical Power Group (TPG) at the University of Genoa.
Experimental tests were carried out to compare MPC against classic PID method: load following tests were carried out. Ramping the fuel cell load from 100% to 80% and back, keeping constant the target of the cathode inlet temperature, the MPC controller was able to reduce the mismatch between the actual and the target values of the cathode inlet temperature from 7 K maximum of the PID controller to 3 K maximum, showing more stable behavior in general.