bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Partial Admission on the Downstream Stages of a Reaction Turbine: An Analytical Approach Verified by Measurements
Authors: Beer Wolfgang , Hirsch Peter 
Published: November 2013

Field measurements on an industrial steam turbine with a rated power output of 5.8 MW, consisting of an impulse type control wheel and a reaction part, showed a significant gap of efficiency from the design calulations. It was suspected, that this gap results from underestimation of the loss created by non-uniform inflow conditions to the reaction part due to partial admission. The experimental results and data of experiments done in the 1990s are therefore recalculated to find possible explanations. It turns out, that probably the data considered for verifcation is not complete. When taking the complete data into account, and using an averaging method, the verification calculations show, that the models used for design and recalculation of industrial steam turbines are accurate enough for industrial purposes, but a calculation model for efficiency loss due to partial admission has to be added. In this work non-uniformity between the flow passages was not observed for the test turbine. Non-uniformity of the flow in radial direction was observed for the test turbine, but was not taken into consideration here, as the whole rotor was treated integrally. Flow seperations as unsteady effects were not considered, as a steady-state investigation was conducted.
The calculation models are verified by comparison with field measurement data from industrial steam turbines, by comparison with the results of a 9 MW steam driven test turbine and by recalculated results from literature. Not all verification calculations are presented in detail here.
Study of Steady State and Transient Blade Row CFD Methods in a Moderately Loaded NASA Transonic High-Speed Axial Compressor Stage
Authors: Qizar Mohammed Abdullah , Mansour Mahmoud L. , Goswami Shraman 
Published: November 2013

The effect of blade row interaction and hub leakage flow on the performance of moderately loaded NASA transonic hybrid compressor stage (Rotor 35 / Stator 37) is investigated through three-dimensional steady state and time-accurate, Navier Stokes calculations of the stage using the ANSYS CFX code at peak efficiency and near stall operating conditions. Understanding unsteady flow phenomena in compressor stages requires the use of time-accurate CFD simulations. Due to the inherent differences in blade counts between adjacent blade rows, the flow conditions at any given instant in adjacent blade rows differ. Depending on the blade counts, it may be necessary to model the entire annulus of the stage; however, this requires considerable computational time and memory resources.
Several methods for modeling the transient flow in turbo machinery stages which require a minimal number of blade passages per row, and therefore reduced computational demands, have been presented in the literature. Recently, some of these methods have become available in commercial CFD solvers. The paper describes the steady and the unsteady CFD approaches used for investigating the ability to predict the measured performance of the NASA transonic axial stage design known as the hybrid stage, which consists of the axial Rotor35 and the axial stator 37. The steady approach employs the mixing-plane while the unsteady approaches are URANS with one based on full annulus simulation for the stage and the second enables simulations for the stage using reduced computational model, with a single passage from each blade row based on the time-tilting or the time-transformation technique.
The above methods are evaluated and compared in terms of computational efficiency and comparison is made to steady stage simulations. Comparisons to overall performance data and two-dimensional Laser Doppler Velocimeter measurements of the velocity field are used to assess the predictive capabilities of the methods. Computed flow features are examined, and compared with reported measurements. This paper presents validation and calibration of methods used for determining blade row interactions and the respective predictive capabilities against the full annulus and the experimental test data.
An Off-Design Performance Prediction Model for Low-Speed Double-Discharge Centrifugal Fans
Authors: Wolfe Tristan , Lee Yu-Tai , Slipper Michael E. 
Published: November 2013

A generalized model for mapping the trend of the performance characteristics of a double-discharge centrifugal fan is developed based on the work by Casey and Robinson (C&R) which formulated compressor performance maps for tip-speed Mach numbers ranging from 0.4 to 2 using test data obtained from turbochargers with vaneless diffusers. The current paper focuses on low-speed applications for Mach number below 0.4. The C&R model uses four non-dimensional parameters at the design condition including the flow coefficient, the work input coefficient, the tip-speed Mach number and the polytropic efficiency, in developing a prediction model that requires limited geometrical knowledge of the centrifugal turbomachine. For the low-speed fan case, the C&R formulas are further modified to apply a low-speed, incompressible analysis.
The effort described in this paper begins by comparing generalized results using efficiency data obtained from a series of fan measurements to that using the C&R model. For the efficiency map, the C&R model is found to heavily depend on the ratio of the flow coefficient at peak efficiency to that at the choke flow condition. Since choke flow is generally not applicable in the low-speed centrifugal fan operational environment, an alternate, but accurate estimation method based on fan free delivery derived from the fan test data is presented. Using this new estimation procedure, the modified C&R model predicts reasonably well using the double-discharge centrifugal fan data for high flow coefficients, but fails to correlate with the data for low flow coefficients. To address this undesirable characteristic, additional modifications to the C&R model are also presented for the fan application at low flow conditions.
A Reynolds number correction is implemented in the work input prediction of the C&R model to account for low-speed test conditions. The new model provides reasonable prediction with the current fan data in both work input and pressure rise coefficients. Along with the developments for the efficiency and work input coefficient maps, the use of fan shut-off and free delivery conditions are also discussed for low-speed applications.
Materials Considerations for Supercritical CO2 Turbine Cycles
Authors: Wright I. G. , Pint B. A. , Shingledecker J. P. , Thimsen D. 
Published: November 2013

Proposed open and closed Brayton-type cycle systems employing supercritical CO2 (sCO2) as the working fluid develop hot gas path environments that present challenging requirements of strength and environmental resistance for the materials of construction. The likely materials properties required by different cycle configurations are examined and compared with the capabilities of available materials. In some instances where peak operating conditions in the turbines in closed-cycle systems approach 500°–700°C at 200 bar, or 1150°C at 300 bar for open cycles, the range of available alloys with the requisite temperature-strength and capabilities is limited.
The cycles are highly recuperated: hot, lower-pressure turbine exhaust is used to pre-heat high-pressure CO2 entering the external heater or combustor just upstream of the turbine. Obviously, there is a need to match alloy capabilities with the performance requirements of individual components. Where alloys are employed under conditions beyond current experience, or in unusual configurations (the unique properties of sCO2 may impact the design of some components), practical acceptance will depend on successful qualification testing involving close collaboration among equipment manufacturers, materials suppliers, and materials research and development groups.
Examination of the range of scenarios published for sCO2 turbine systems suggests that approaches used in the U.S. Advanced, Ultra-Supercritical (A-USC) Steam Boiler program, and some of the data generated for fabrication, joining, mechanical properties, and performance in simulated service environments in that program, will be applicable to some of the components in these systems. An attempt to elaborate and prioritize the materials property and qualification activities required for the successful realization of these sCO2 cycles is presented as a guide to activities needed to facilitate materials selection.
Axial-Slot Casing Treatments Improve the Efficiency of Axial Flow Compressors: Aerodynamic Effects of a Rotor Redesign
Authors: Streit J. Anton , Heinichen Frank , Kau Hans-Peter 
Published: November 2013

A state-of-the-art transonic compressor rotor has a distinct potential for increased efficiency if modified for improved interaction with an axial-slot type casing treatment. Reducing the number of blades and thus the surface lowers friction losses but increases tip clearance effects and deteriorates the stall margin due to the higher aerodynamic blade loading. The latter two negative effects can be compensated for by the casing treatment, thus restoring the required stall margin and gaining an overall reduction of losses. For the specific compressor rotor under investigation, the potential in polytropic efficiency is as high as 0.7%.
The present study was performed using time-accurate CFD (URANS) simulations. Both the reference rotor as well as the modified design are analyzed regarding their interaction with the casing treatment. The traceability of the conclusions is assured by interpreting the detailed flow phenomena. The newly designed rotor is found to be favorably influenced by the casing treatment at design operating conditions whilst the reference only benefits at throttled operating points.
Casing treatments are commonly used to broaden the operating range of existing compressors without changing the design of the compressor rotor itself. This study aims to show the possible transformation of this potential in the stall margin into efficiency at design operating conditions by implementing an appropriate rotor design.
Modelling and Validation of the Nonlinear Dynamic Behaviour of Bolted Flange Joints
Authors: Schwingshackl C. W. , Di Maio D. , Green J. S. 
Published: November 2013

Linear dynamic finite element analysis can be considered very reliable today for the design of aircraft engine components. Unfortunately, when theses individual components are built into assemblies, the level of confidence in the results is reduced, since the joints in the real structure introduce nonlinearity that cannot be reproduced with a linear model. Certain types of nonlinear joints in an aircraft engine, such as underplatform dampers and blade roots, have been investigated in great detail in the past, and their design and impact on the dynamic response of the engine is now well understood. With this increased confidence in the nonlinear analysis, the focus of research now moves towards other joint types of the engine which must be included in an analysis to allow an accurate prediction of the engine behaviour.
One such joint is the bolted flange, which is present in many forms on an aircraft engine. Its main use is the connection of different casing components to provide the structural support and gas tightness to the engine. This flange type is known to have a strong influence on the dynamics of the engine carcase. A detailed understanding of the nonlinear mechanisms at the contact is required to generate reliable models and this has been achieved through a combination of an existing non-linear analysis capability and an experimental technique to accurately measure the nonlinear damping behaviour of the flange. Initial results showed that the model could reproduce the correct characteristics of flange behaviour, but the quantitative comparison was poor. From further experimental and analytical investigations it was identified that the quality of the flange model is critically dependent on two aspects: the steady stress/load distribution across the joint and the number and distribution of non-linear elements. An improved modelling approach was developed which led to a good correlation with the experimental results and a good understanding of the underlying nonlinear mechanisms at the flange interface.
Design and Commissioning of an Engine-Like Test Environment
Authors: Laing Malcolm , Pickering Todd , Kominsky Dan , O’Brien Walter , Poland Steve 
Published: November 2013

Test and evaluation are critical to any product development program. The validation of engine sensor products is particularly challenging since the test engine required for validation can range in value from thousands to millions of dollars, costing much more than the sensor product itself. As a result, significant sensor testing and validation is required by an engine owner prior to on-engine testing. To support our development activities and to facilitate test validation acceptance, we have created a test and evaluation platform for gas turbine sensors that will allow us to test developmental sensors in an engine-like environment without risking the possibility of engine damage. Driven by the core exhaust of a JT15-D engine, the Dynamic Rotor Research Rig (DR3) test and evaluation platform provides a test capability that is highly representative of the high temperatures, vibrations, gasses, fluids and overall gas turbine engine environment, while providing the means to easily add and replace sensors, add and test custom rotors, control temperature and rotor speeds, and to not risk engine health during test activities.
Here we will discuss our sensor testing goals and how they fed into the operational goals and design considerations for the DR3. Early design concepts and the ultimate approach we took with the DR3 design will be explored, along with the candidate test rig component and subassembly fabrication processes that we evaluated and ultimately selected for use. We will review the manufacturing issues that we encountered during the construction phase of the DR3 and overview the commissioning of the DR3, problems that we discovered during start up and how we solved them.
Included will be the results of initial turbine blade clearance and blade tip timing sensor testing performed on the DR3 and an evaluation of the DR3 performance, including temperature and speed control of the test rig and other characterization of the operating regime of the rig. Finally, we will present future plans to upgrade the DR3 rig to support future high temperature sensor and blade health monitoring development activities.
Turbomachinery for a Supercritical CO2 Electro-Thermal Energy Storage System
Authors: Fuller R. , Hemrle J. , Kaufmann L. 
Published: November 2013

This paper presents analysis of CO2 turbomachinery for the electro-thermal energy storage (ETES) concept for site-independent bulk (grid-scale) electric energy storage. In charging mode, ETES operates as a transcritical CO2 heat pump, consuming electric energy which is converted into thermal energy stored in the form of hot water and ice on the hot and cold side of the cycle, respectively. On demand, the CO2 cycle is reversed for discharging during which ETES operates as transcritical CO2 power generation plant, consuming the stored hot and cold sources. The target capacity of the ETES system is of the order of units of MW electric to ∼100 MW electric, with typical daily cycles and 4 to 8 hours of storage. The estimated electric-to-electric round trip efficiency of ETES is about 60%.
A companion paper [1] presents the control concept of the ETES plant and discusses several issues specific to the ETES plant design and operation. This paper analyzes these particular requirements from the perspective of the CO2 turbomachinery required for the storage plant, presenting the selection of the turbomachinery types and their shaft arrangement suitable for the ETES. The expected performance, main design features and challenges are discussed, together with questions related to the scalability of the turbomachines towards high power targets. Impacts of the turbomachinery designs on the ETES system performance, such as the sensitivity of the system electric-to-electric round trip efficiency on the turbomachinery efficiency are discussed.
Application of the Multi-Axial Creep Failure Method on Double Reheat Thermodynamic Cycle Turbine
Authors: Chen Gang , Jiang Puning , Wang Yuxiang , Hao Zhenzhen 
Published: November 2013

With the development of higher efficiency and lower consumption plants, higher steam parameters to 600/620/620°C and 33/10.6/3.5MPa and double reheat thermodynamic cycle system are adopted for the power plant. Thus, it is believed that the safety of high temperature components in the steam turbine system is a critical issue that could not be circumvented in the period of modern industrial development. To achieve a reliable design, manufacture and the desired long-term operation of the high temperature components in steam turbine, many fundamental research concerning design criteria and life prediction has been studied. However, for the steam turbine original equipment manufacturer (OEM) which design criteria and life prediction model are suitable for their product and how to accurately assess the components’ life under long-term operation is still a critical issue. For all confronted problems, the multi-axial creep failure is one of the major problems in the life prediction for high temperature components, and it is an important factor to be considered in the high temperature components design.
In this paper, the creep failure mechanisms of high temperature components in steam turbine which under multi-axial stress states are analyzed, and the design criteria for creep strain and stress are presented which are based on cavity growth theory. The application of the method and design criteria in a medium pressure turbine which is included in a double reheat thermodynamic cycle plant is presented.
Experience With Gas Path Analysis for On-Wing Turbofan Condition Monitoring
Authors: Verbist Michel L. , Visser Wilfried P. J. , van Buijtenen Jos P. 
Published: November 2013

Gas path analysis (GPA) is an effective method for determination of turbofan component condition from measured performance parameters. GPA is widely applied on engine test rig data to isolate components responsible for performance problems, thereby offering substantial cost saving potential. Additional benefits can be obtained from the application of GPA to on-wing engine data.
This paper describes the experience with model-based GPA on large volumes of on-wing measured performance data. Critical is the minimization of the GPA results uncertainty in order to maintain reliable diagnostics and condition monitoring information. This is especially challenging giving the variable in-flight operating conditions and limited on-wing sensor accuracy. The uncertainty effects can be mitigated by statistical analysis, and filtering and post-processing of the large datasets. By analyzing correlations between measured performance data trends and estimated component condition trends errors can be isolated from the GPA results. The various methods assessed are described and results are demonstrated in a number of case studies on a large turbofan engine fleet.
Experimental Analysis of Flow Unbalance in Two Parallel Counter-Flow Recuperators
Authors: Martini Alessio , Traverso Alberto , Tucker David , VanOsdol John 
Published: November 2013

The aim of this study was to provide a characterization of non-symmetrical operation in two counter-flow primary surface exhaust gas recuperators installed in parallel flow loops. The hybrid system emulator test rig and facility designed and operated by the Department of Energy, National Energy Technology Laboratory located at the West Virginia (USA) campus was used for the study. Various tests from the past years often resulted in non-symmetrical operation, indicated by significantly variant temperature measurements at the outlets of the recuperators.
Some specific tests have been carried out in order to identify the possible cause of this flow unbalance. The isolated effects of bleed air, cold air and hot air valve on the heat exchangers flow unbalance have been studied. Also, the impact of load bank changes on flow distribution has been considered in this study. Each test has been carried out in close loop fuel valve speed control. The influence of each independent variable in the study on parallel recuperator flow distribution has been quantitatively characterized using temperatures and a heat balance. Both the bleed and the cold air compressor bypass valves showed an appreciable impact on the heat exchangers flow unbalance, while hot air valve and load bank changes had minimal effect.
An Experimental and Theoretical Investigation of Wave Propagation in Teflon and Nylon Tubing With Methods to Prevent Aliasing in Pressure Scanners
Authors: Hurst Adam M. , VanDeWeert Joe 
Published: November 2013

Accurate static and dynamic pressure measurements provide the feedback needed to advance gas turbine efficiency and reliability as well as improve aircraft design and flight control. During turbine testing and aircraft flight testing, flush mounting pressure transducers at the desired pressure measurement location is not always feasible and recess mounting with connective tubing is often used as an alternative. Resonances in the connective tubing can result in aliasing within pressure scanners even within a narrow bandwidth and especially when higher frequency content DC to ∼125Hz is desired. We present experimental results that investigate tube resonances and attenuation in 1.35mm inner diameter (ID) (used on 0.063in tubulations) and 2.69mm ID (used on 0.125in tubulations) Teflon and Nylon tubing at various lengths. We utilize a novel dynamic pressure generator, capable of creating large changes in air pressure (<1psi to 10psi, <6.8kPa to 68.9kPa), to determine the frequency response of such tubing from ∼1Hz to 2,800Hz. We further compare these experimental results to established analytical models for propagation of pressure disturbances in narrow tubes. While significant theoretical and experimental work relating to the frequency response of connective tubing or transmission lines has been published, there is limited literature presenting experimental frequency response data with air as the media in elastic tubing. In addition, little progress has been made in addressing the issue of tubing-related aliasing within pressure scanners, as the low sampling rate in scanners often makes post-processing antialiasing filters ineffective.
The experimental results and analytical models presented herein can be used as a guideline to prevent aliasing and signal distortion by guiding the proper design of pressure transmission systems, resulting in accurate static and dynamic pressure measurements with pressure scanners. The data presented here should serve as a reference to instrumentation engineers so that they can make higher frequency measurements (up to ∼125Hz, currently) and are able to quantify the expected pressure transmission line (tube) attenuation and know if aliasing will be a concern. This information will give engineers greater measurement capability when using pressure scanners to make static and dynamic pressure measurements.