bluuebunny/crossref_metadata_2025_split huggingface dataset:
Film-Cooled Turbine Endwall in a Transonic Flow Field: Part II — Heat Transfer and Film-Cooling Effectiveness
Authors: Nicklas Martin 
Published: July 2014

Thermodynamic and aerodynamic measurements were carried out in a linear turbine cascade with transonic flow field. Heat transfer and adiabatic film-cooling effectiveness resulting from the interaction of the flow field and the ejected coolant at the endwall were measured and will be discussed in two parts. The investigations were performed in the Windtunnel for Straight Cascades (EGG) at the DLR, Goettingen. The film-cooled NGV endwall was operated at representative dimensionless engine conditions of Mach and Reynolds number Ma2is=1.0 and Re2=850,000 respectively.
Part II of the paper discusses the thermodynamic measurements. Detailed temperature measurements were carried out on a turbine stator endwall. In order to determine the surface heat transfer and adiabatic film-cooling effectiveness, an infrared camera system in a rectilinear wind tunnel measured the endwall temperatures in the transonic flow field. The adiabatic film-cooling effectiveness was determined using the superposition method. Measurements were carried out to first, validate the assumptions of theory and second, analyse the error associated with the measurements. Effects of coolant ejection from a slot and three rows of holes were investigated and compared with each other. The influence of Mach number and blowing ratio on the heat transfer were further aspects of the investigation. Strong variations in heat transfer and film-cooling effectiveness due to the interaction of the coolant air and the secondary flow field were found. Based on the results of this investigation an improved cooling design will be investigated in a follow-up project.
Quasi Two-Dimensional Cyclone-Jet Cooling Configuration: Evaluation of Heat Transfer and Pressure Losses
Authors: Khalatov Artem A. , Syred Nick , Bowen Philip J. , Al-Ajmi Rashed 
Published: July 2014

Heat transfer and pressure losses have been studied in a cyclone-jet chamber to evaluate its the thermal efficiency and thermal-hydraulic performance. The cyclone chamber simulates the leading edge area, it is 4.2 mm in diameter and 35 mm long and has four injecting and five discharging round-shaped holes evenly spread and facing the chamber stagnation point. Such a configuration generates a quasi two-dimensional swirl flow pattern accompanied with flow separation effects. Three test sections with various inlet and outlet hole diameter have been studied to evaluate the effect of boundary conditions. The Heating in Melted Metal (HMM) experimental technique has been employed to measure heat transfer parameters.
The local spanwise heat flux distribution has a periodical characteristic with a maximum opposite the injecting holes and a minimum in between them. The non-uniformity of the heat flux depends on the diameter of inlet holes and the air mass flow rate. The angular distribution of an averaged spanwise heat transfer is asymmetrical with respect to the chamber stagnation point; it is either actually a ‘flat curve’ or has a maximum at the stagnation point. An average heat transfer in the cyclone chamber is 2.61 – 3.54 higher compared with its axial counterpart. The basic heat transfer correlations are presented in addition to the thermal efficiency and thermal-hydraulic performance evaluation made. The proposed cyclone-jet design is as good as a serpentine cyclone cooling and some advanced cooling techniques, but more simple production technology is an undoubted advantage of this configuration.
Measurements of the Effects of Pressure-Gradient History on Separation-Bubble Transition
Authors: Yaras M. I. 
Published: July 2014

In many boundary-layer situations, particularly in turbomachinery, separation-bubble transition occurs at a local pressure gradient that differs significantly from the values further upstream. Additionally, this upstream history changes substantially from case to case, with the transitioning separation bubble occurring at streamwise positions along the blade chord varying from close vicinity of the leading edge to mid-chord. In the case of low free-stream disturbances, development of instability waves prior to separation would clearly vary as a result of these differences in the history of the boundary layer prior to separation.
Measurements are presented to document the effects of pressure gradients that a laminar boundary layer experiences prior to separation on the transition process that follows in the separated region. The boundary layer development was measured on a smooth, flat plate upon which streamwise pressure gradients were imposed by a flexible, contoured wall opposite to the test plate. Only low freestream-turbulence levels were considered to isolate the effects of pressure-gradient history on the transition process. Two Reynolds numbers were considered for each pressure-gradient setting. Measured quantities consisted of velocity and turbulence intensity obtained with a single hot-wire, and of surface pressures. Observed variations in transition onset location with changes in pressure-gradient history provide the basis for further development of current transition prediction schemes.
Computational and Mathematical Modelling of Turbine Rim Seal Ingestion
Authors: Hills Nicholas J. , Chew John W. , Turner Alan B. 
Published: July 2014

Understanding and modelling of main annulus gas ingestion through turbine rim seals is considered and advanced in this paper. Unsteady 3-dimensional computational fluid dynamics (CFD) calculations and results from a more elementary model are presented and compared with experimental data previously published by Hills et al (1997). The most complete CFD model presented includes both stator and rotor in the main annulus and the inter-disc cavity. The k-ε model of turbulence with standard wall function approximations is assumed in the model which was constructed in a commercial CFD code employing a pressure correction solution algorithm. It is shown that considerable care is needed to ensure convergence of the CFD model to a periodic solution. Compared to previous models, results from the CFD model show encouraging agreement with pressure and gas concentration measurements. The annulus gas ingestion is shown to result from a combination of the stationary and rotating circumferential pressure asymmetries in the annulus. Inertial effects associated with the circumferential velocity component of the flow have an important effect on the degree of ingestion.
The elementary model used is an extension of earlier models based on orifice theory applied locally around the rim seal circumference. The new model includes a term accounting for inertial effects. Some good qualitative and fair quantitative agreement with data is shown.
Coupled Fluid/Solid Heat Transfer Computation for Turbine Discs
Authors: Verdicchio John A. , Chew John W. , Hills Nick J. 
Published: July 2014

This paper considers the coupling of a finite element thermal conduction solver with a steady, finite volume fluid flow solver. Two methods were considered for passing boundary conditions between the two codes — transfer of metal temperatures and either convective heat fluxes or heat transfer coefficients and air temperatures. These methods have been tested on two simple rotating cavity test cases and also on a more complex real engine example.
Convergence rates of the two coupling methods were compared. Passing heat transfer coefficients and air temperatures was found to give the quickest convergence. The coupled method gave agreement with the analytic solution and a conjugate solution of the simple free disc problem. The predicted heat transfer results for the real engine example showed some encouraging agreement, although some modelling issues are identified.
Thermo-Economic Optimization of a Cogeneration Plant With Below Ambient Pressure Discharge Gas Turbine
Authors: Bianchi M. , Negri di Montenegro G. , Peretto A. 
Published: July 2014

The gas turbine use in cogeneration plants for thermal and electric power production is constantly increasing especially for low power requirements.
In this paper, firstly a thermodynamic analysis of a Below Ambient pressure discharge Gas Turbine (BAGT) has been evaluated and the BAGT cogenerative performance compared with those of a Brayton Cycle (BC) cogenerative power plant.
Subsequently, an economic investigation of BAGT is carried out and the benefits, with respect to BC, evaluated.
It resulted that the BAGT presents a higher electric efficiency and its employment may strongly increase the budget at disposal for the cogenerative plant investment.
Management of High Speed Machinery Signatures to Meet Stealth Requirement in the Royal Swedish Navy Visby Class Corvette (YS 2000)
Authors: Liwång Hans , Pejlert Lars , Miller Steve , Gustavsson Jan-Erik 
Published: July 2014

Over the years, the word stealth has been used more and more when discussing design and operational characteristics in military applications. New and more challenging techniques are constantly being applied to minimize signatures and thus hinder or delay detection and identification.
The Visby Class Corvette is a multipurpose combat ship with 600 tons displacement. The hull is a sandwich construction of a PVC core with carbon fiber/vinyl laminate. The propulsion system consists of two identical CODOG machinery systems, each driving a KaMeWa 125 size Water Jet Unit.
The Ship has special requirements for all signatures, i.e. Radar-, Hydro acoustics-, IR- and Magnetic Signature. The High Speed Machinery is twin Honeywell TF50A Gas Turbines, cantilever mounted side by side on the Main Reduction Gearbox housing. The Main Reduction Gearbox is a dual input high performance marine Gearbox designated MA - 107 SBS, designed and manufactured by Cincinnati Gear Co. The Low Speed Machinery is a MTU 16 V 2000 TE90 Diesel Engine connected to the MRG by a power take in shaft.
Combustion Air for the Gas Turbines is ducted from the shipside Air Inlet Screen (radar screen) via 3-stage separating filters. The Exhausts from the twin Gas Turbines are combined into one Exhaust Pipe and ducted to the ship transom above the Water Jet stream.
Very little can be changed in the Gas Turbine, but high quality such as well balanced rotating part contributes to reduce the signatures. However, the main work has to be accomplished by the building shipyard in cooperation with the Gas Turbine manufacturer. The Main Reduction Gearbox is more available for changes to reduce signatures, but even for the Gearbox the building shipyard has to take design and installation measures.
The HSM installation consist mainly of the Gas Turbine Engine, the Main Reduction Gear, Water Jets Unit and surrounding equipment such as main shaft, bearings and so on. The emphasis in this paper is on the GT, MRG and their effect on some of the more well known signatures i.e. RCS, IR, Hydro acoustics and Magnetic. Also some design measures are discussed.
Turbocompressor Revamp: A Low Cost Modification to Considerable Efficiency Improvement
Authors: Skorping Roald , Underbakke Harald 
Published: July 2014

Depletion of oil and gas reservoirs will gradually reduce the wellhead pressure. Consequently, the process equipment for separation and transport of oil and gas will move into off-design operation with reduced efficiency. Turbocompressors are critical equipment used for re-compression, injection or transport of natural gas. Off-design operation may result in a major compressor efficiency drop.
Statoil operates several offshore North Sea process platforms where reduction in wellhead pressure is a challenge. This paper describes the experience with compressor revamp on one onshore and one offshore process plant covering scope of work / supply, installation, testing, operation and cost/benefit analyses.
The processing facility on Statoil’s Troll A platform in the North Sea interacts with the installations at the Kollsnes gas treatment plant near Bergen, where natural gas is transported to the European Continent by the world’s largest variable speed electrical drive pipeline compressors. Changes in gas inlet conditions required revamping in order to adapt the compressor performance to existing process conditions. In addition, a high performance 3 dimensional rotor design was installed in the old compressor casing.
Sleipner East and Sleipner West lie in the Norwegian North Sea. The first of these gas and condensate fields came on stream in October 1993. After gradually reduction of the wellhead pressure on the Sleipner A processing platform, it was decided to modify the processing facilities and revamping of two gas turbine driven re-compressors were required.
Gearbox Failure of a Turbogenerator Set
Authors: Rao J. S. , Peraiah K. Ch. 
Published: July 2014

A 6 MW Turbogenerator suffered a catastrophic failure on 26th December 1999 due to a ground fault in the line. The turbine along with the transmission unit and both the couplings failed in this accident.
The turbogenerator set is modeled for torsional vibration analysis as a multi degree of freedom system. The natural frequencies and mode shapes are obtained. The system is next modeled as an equivalent four rotor system and a short circuit analysis is made to determine the magnification factor in this period. A complete gear box analysis has been made for its fatigue life and it was shown that it is just not capable of withstanding even a single alternating stress arising from the short circuit. The pinion will fail under short circuit condition.
Dynamics of Labyrinth Gas Seals With Air Injection
Authors: Kwanka K. 
Published: July 2014

Exciting forces generated in gas seals and blading of turbo-machinery can lead to vibrations of the rotor with unacceptably high amplitudes (Thomas [1958], Alford [1965]). It is important to predict in an early design stage the stability limit of the rotor so as to avoid the occurrence of self-excited vibrations. In the field, there are only few possibilities to stabilize the rotor. One way minimizing the cross-forces is by injecting air into the seal and counteracting the exciting mechanisms.
The paper will present experimental dynamic coefficients of a gas seal of the teeth on stator type with eight cavities. The coefficients will be compared to the values obtained with a tangential injection of air into the first cavity in co-rotating and in counter-rotating direction. It seems that the impact of air injection is not as effective as swirl brakes or honeycomb stators.
Numerical Investigation of Blade Flutter at or Near Stall in Axial Flow Turbomachines
Authors: Höhn Wolfgang 
Published: July 2014

During the design of the compressor and turbine stages of today’s aeroengines, aerodynamically induced vibrations become increasingly important since higher blade load and better efficiency are desired. In this paper the development of a method based on the unsteady, compressible Navier-Stokes equations in two dimensions is described in order to study the physics of flutter for unsteady viscous flow around cascaded vibrating blades at stall.
The governing equations are solved by a finite difference technique in boundary fitted coordinates. The numerical scheme uses the Advection Upstream Splitting Method to discretize the convective terms and central differences discretizing the viscous terms of the fully non-linear Navier-Stokes equations on a moving H-type mesh. The unsteady governing equations are explicitly and implicitly marched in time in a time-accurate way using a four stage Runge-Kutta scheme on a parallel computer or an implicit scheme of the Beam-Warming type on a single processor. Turbulence is modelled using the Baldwin-Lomax turbulence model. The blade flutter phenomenon is simulated by imposing a harmonic motion on the blade, which consists of harmonic body translation in two directions and a rotation, allowing an interblade phase angle between neighboring blades. Non-reflecting boundary conditions are used for the unsteady analysis at inlet and outlet of the computational domain. The computations are performed on multiple blade passages in order to account for nonlinear effects. A subsonic massively stalled unsteady flow case in a compressor cascade is studied. The results, compared with experiments and the predictions of other researchers, show reasonable agreement for inviscid and viscous flow cases for the investigated flow situations with respect to the Steady and unsteady pressure distribution on the blade in separated flow areas as well as the aeroelastic damping.
The results show the applicability of the scheme for stalled flow around cascaded blades. As expected the viscous and inviscid computations show different results in regions where viscous effects are important, i.e. in separated flow areas. In particular, different predictions for inviscid and viscous flow for the aerodynamic damping for the investigated flow cases are found.
A Parametric Study of a Cottage-Roof Damper and Comparison With Experimental Results
Authors: Jareland Martin H. 
Published: July 2014

Platform dampers are commonly used in turbomachinery to reduce the vibration amplitudes of the turbine blades. A blade-to-blade platform damper is simply a piece of metal which is pressed against two adjacent blade platforms by centrifugal force. Relative motions of the platforms lead to slip in the contacts and friction damping is provided in the system. The studied platform damper is designed with inclined contact surfaces. This type of damper is often called a cottage-roof damper or wedge damper. The inclination of the contact surfaces leads to variation of the normal load, which complicates the analysis of such dampers.
In this paper, a simulation model is presented for a tuned bladed disk with cottage-roof dampers. This model includes normal load variation on the contact and a friction interface model valid for both macroslip and microslip. The elasticity of the damper body is often an important parameter for the performance of the damper and is included in the model.
A comparison between solving the equation of motion in the frequency domain and the time domain is performed. It is found that the frequency domain solution with the fundamental frequency alone gives a result close to the time domain solution. The simulation model is validated with experimental data and it is found that the reduction of the resonance amplitude agrees well for the tested dampers.
A parametric study is performed to find the optimal friction damper design. The studied parameters are the inclination of the contact surface, the coefficient of friction and the damper body stiffness. It is found that an increase in inclination of the contact surface and an increase in the coefficient of friction lead to a reduction of the optimal damper mass. An increase of the damper body stiffness results in a decrease of the resonance amplitude of the blade tip, particularly for high damper masses.
Design Improvements of the EJ 200 HP Compressor: From Design Verification Engine to a Future All Blisk Version
Authors: Kosing O. E. , Scharl R. , Schmuhl H. J. 
Published: July 2014

The EJ 200 engine powers the Eurofighter / Typhon combat aircraft and is being built by the four nations UK (RR), Germany (MTU), Italy (FIAT AVIO) and Spain (ITP). The engine is capable of 60 kN dry thrust and 90kN reheat thrust with a 15% built in growth potential. The specific thrust to weight ratio is ≈ 10 and the overall pressure ratio 26.
MTU’s 33% work - share package contains the development of the three stage LP Compressor, the five stage HP Compressor and the Digital Engine Control Unit.
This paper concentrates on the five stage axial HP Compressor. It describes the major design changes from the very first design verification engine (DVE) to a future all blisk version. It first provides a brief historical overview of the major design improvements which are then discussed in detail.
The rotor concept is discussed with respect to life, weight, material and repair.
The development of the casing to improve the tip clearance behaviour, the containment and the protection against titanium fire is outlined.
The stator concept is described in connection with an intense cost reduction program.
The HP Compressor has successfully completed testing and flight clearance has been approved for all standards. Thus far the HPC has accumulated more than 16500 hours total engine experience and over 1040 Eurofighter flights. The production engine manufacturing is in progress, with the first engine to be delivered in March 2001.
Clocking Effects in a 1.5 Stage Axial Turbine: Steady and Unsteady Experimental Investigations Supported by Numerical Simulations
Authors: Reinmöller U. , Stephan B. , Schmidt S. , Niehuis R. 
Published: July 2014

The interaction between rotor and stator airfoils in a multistage turbomachine causes an inherently unsteady flow field. In addition, different relative circumferential positions of several stator rows and rotor rows, respectively, have an influence on the flow behaviour in terms of loss generation, energy transport and secondary flow. The objective of the presented study is to investigate the effects of stator airfoil clocking on the performance of an 1-1/2 stage axial cold air turbine. The investigated axial turbine consists of two identical stators. The low aspect ratio of the blades and their prismatic design leads to a three-dimensional outlet flow with a high degree of secondary flow phenomena. Nevertheless, the small axial gaps between the blade rows are responsible for strong potential flow interaction with the radial wake regions in the measurement planes. Consequently, parts of the wakes of the first stator are clearly detected in the rotor outlet flow.
To give an overview of the time-averaged flow field, measurements with pneumatic probes are conducted behind each blade row at ten different clocking-positions of the second stator. Further, an optimised clocking position was found due to a minimum in pressure loss behind the 2nd stator. The unsteady measurements are carried out with hot-wire probes for three selected stator-stator positions. Animations of selected flow properties show the influence of different circumferential positions of the second stator on the unsteady flow behaviour and secondary flow field. In addition and compared with experimental results three-dimensional unsteady viscous flow computations are performed.