bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wireless Telemetric Data Acquisition and Real-Time Control for a High Measurement-Density Internal Heat Transfer Experiment
Authors: Habib Alexander J. , Barton Jeffery L. , Mathison Randall M. , Dunn Michael G. 
Published: September 2014

This paper describes a wireless data transmission system for a large-scale rotating experiment to investigate the heat transfer in a three-passage serpentine test section. Patterned after the NASA HOST program, the current experiment extends the data set to larger aspect ratios including 1:2, 1:4 and 1:6. As with HOST, heat transfer is measured using the heated conducting segments technique, and the serpentine test section spins at rotation numbers representative of engine conditions. Rotating experiments are essential for capturing the representative operating conditions and complicated flow physics that must be understood to advance internal cooling technology for these high aspect ratio configurations.
There are challenges associated with controlling the operating parameters and collecting accurate data for high measurement-density rotating experiments. This experiment requires that 140 copper panels be held at a constant temperature by independently controlling and recording the power supplied to a separate heater on each panel. This means there must be 140 temperature measurements, 140 pairs of heater power leads, enough power to drive all of these heaters, and data recording capacity left over to measure fluid temperatures and pressures. Traditional methods of transferring rotating signals to the stationary frame of reference (such as slip rings) are widely implemented but have practical limitations in the quantity of transferrable signals and the electrical current capacity of the individual channels. Alternatively, wireless transmission techniques were first developed decades ago, but their practical use has been limited by onboard power delivery requirements and cost.
This paper describes the development of a new data transmission and control system that takes advantage of improvements in low-cost off-the-shelf electronics to create a battery powered and microprocessor controlled system for acquisition, storage, control, and wireless communication. These components are assembled to form an integral part of the rotating mechanical hardware. By handling high-fidelity microcircuit signal conditioning, data acquisition, feedback control, and data storage in the rotating frame and transmitting the results with two-way wireless communication, this system provides high measurement density and active feedback control that would have been impractical with a conventional slip-ring approach.
The design and construction of the wireless control system for one full sidewall of the three-serpentine passage is described in detail. Its capability and functionality is demonstrated with operational data. It will be demonstrated that while all of the components in this system are readily available, the unique combination of this technology opens up a new world of measurement capabilities.
ASME PTC-10 Performance Testing of Centrifugal Compressors — The Real Gas Calculation Method
Authors: Taher Matt 
Published: September 2014

ASME PTC-10 (2009) provides a test procedure to determine the thermodynamic performance of centrifugal compressors for gases conforming to ideal gas laws and for real gases. It requires using real gas calculation methods where the compressibility values depart from the specified limits. ASME PTC-10 employs Schultz X and Y compressibility factors to calculate the polytropic exponent for real gas compression. Specific values of X and Y for the test gas at the test condition may be different from the values provided in ASME PTC-10 generalized charts. Therefore, special care should be taken to properly calculate X and Y factors for a test gas at specified conditions.
In this paper, Schultz compressibility factors X and Y are derived as functions of reduced properties. These functions can be used with any equation of state to precisely calculate X and Y values for any gas composition at the specified operating conditions. By using the proposed method, Schultz X and Y compressibility factors for propane are graphically represented covering a reduced pressure range of 0.1 to 3 and a reduced temperature range of 1.05 to 2. Also, the rate of change of polytropic exponents for propane over a wide range of pressures and temperatures is graphically demonstrated.
Integrated “CFD - Acoustic” Computational Approach to the Simulation of Aircraft Fan Noise
Authors: Ferrante Piergiorgio , di Francescantonio Paolo , Hoffer Pierre-Alain , Vilmin Stéphane , Hirsch Charles 
Published: September 2014

An innovative computational approach, integrating mesh generation, CFD simultaneous analysis of noise source and propagation, with acoustic radiation, is presented and applied to the simulation of the Advanced Noise Control Fan (ANCF) developed by NASA Glenn Research Center.
The tonal noise source and the sound propagation in the nacelle duct and in the nacelle near field are simultaneously predicted, starting from the engine geometry and parameters, with a single CFD analysis based on an efficient Nonlinear Harmonic (NLH) method. The sound radiation to the far field is computed with the Green’s function approach implemented in a BEM frequency domain solver of the convective Helmholtz equation.
The present method provides to a gain of close to two orders of magnitude compared to standard approaches, based on full unsteady flow simulations, followed by a near-field FEM based approach and a BEM method for the far-field noise propagation.
The final comparison between the numerical results and the measurements highlights the capability of the methodology to efficiently predict the unsteady flow field and the radiated sound field.
Prediction of 3D Unsteady Flow and Heat Transfer in Rotating Cavity by Discontinuous Galerkin Method and Transition Model
Authors: Tan Qinxue , Ren Jing , Jiang Hongde 
Published: September 2014

Rotating cavities with axial throughflow are found inside the compressor rotors of turbo-machines. The flow pattern and heat transfer in the cavities are known as sophisticated problems. Because of the numerical errors and model errors, as well as the stiffness introduced by low-Ma number, prediction of 3D unsteady flow and heat transfer in rotating cavity is still a challenge for modern CFD technology.
An in-house 3D unsteady CFD code was developed in this study. The discontinuous galerkin method, which can fulfill any high-order accuracy on the unstructured grid, was applied to reduce the discretization errors. The SST-γ-Reθ transition model proposed by Menter was applied to reduce the model errors. To overcome the stiffness and achieve good convergence characteristics and solution quality, the preconditioning matrix technique combined with DG method was introduced for low-Ma number viscous flow. First, natural convection of air in a square cavity was studied to test the code. The feasibility and credibility, of applying the DG method and the preconditioned matrix technique for buoyancy–induced Rayleigh-Bénard like flow, were further verified. Second, the 3D compressible flow field in a rotating cavity was investigated numerically using the FV method, DG method and laminar/SA/SST-transition turbulence model. It is demonstrated that the whole flow structure of all calculated cases was similar after comparing the calculated results with the available experimental data. But, the transition turbulence model fitted the experimental data better. On the other hand, the performance of high-order method was much better for both the rotating cavity flow and natural convection, in terms of heat transfer.
To better understand this phenomenon, an accuracy analysis of heat flux using DG method and FV method was performed. It showed the DG method could realize arbitrary precision of viscous stress and heat fluxes on irregular unstructured grids, while the FV method could only realize the first-order accuracy of the heat fluxes at the boundary faces and may exhibit erroneous behaviors. It also demonstrated that the high-order accuracy of gradients was needed to decrease errors of heat fluxes and viscous stresses, and that DG method was a promising method.
Sensitivity Analysis of Multiharmonic Self-Excited Limit-Cycle Vibrations in Gas-Turbine Engine Structures With Nonlinear Contact Interfaces
Authors: Petrov E. P. 
Published: September 2014

An efficient frequency-domain method is developed to calculate the sensitivity of multiharmonic amplitudes of the limit-cycle oscillations and their primary frequency to variation of the nonlinear contact interface parameters and aerodynamic characteristics. The method allows highly accurate and fast determination of the sensitivity coefficients together with the calculation of the limit-cycle amplitudes and frequencies using realistic large-scale finite element models of structures. The nonlinear contact interactions analysed include: friction contacts, unilateral interaction along normal direction at a contact interface, closing and opening clearances and interferences, cubic spring nonlinearity.
The capabilities of the method are demonstrated on a set of test cases.
Influence of Tip Shroud Cavity Detailing on Turbine Blade Forcing Calculations
Authors: Gezork Tobias , Mayorca María A. , Groth Pieter , Vogt Damian M. , Fransson Torsten 
Published: September 2014

Forced response in turbomachinery refers to the vibration of a component due to an excitation originating from another component. Obstacles, such as struts and blade rows in the upstream and downstream flow path of a turbomachine engine lead to engine order (EO) excitations. To be able to predict the severity of these excitations, both aerodynamic and structural calculations are performed. There is a risk of critical high cycle fatigue (HCF) failure when the force acts at a resonance frequency.
Customarily, forcing calculations exclude detailing features, such as leakage flows. The current investigation uses a two stage subsonic model steam turbine configuration with shrouded rotor blades to demonstrate the influence of neglecting flow through seal cavities for blade forcing predictions. Upstream and down-stream vanes are the excitation sources on the rotor blade. Calculation results are compared for a configuration including and excluding the tip shroud cavity. Computed data is compared to available pressure data from tests in the model turbine.
The investigation shows for the first blade passing excitation at design point that the axial and circumferential rotor forcing change by +22%, respectively +4% when including the tip shroud cavity for the investigated configuration. The change in forcing arises from the interaction of the leakage flow with the main stream flow. For highly loaded designs this can be of importance if there is a critical excitation.
Stability of a Cracked Rotor Subjected to Parametric Excitation
Authors: Sawicki Jerzy , Kulesza Zbigniew 
Published: September 2014

It is well known that parametric vibrations may appear during the rotation of a rotor with a cracked shaft. The vibrations occur due to periodic stiffness changes being the result of crack breathing. A parametrically excited system may exhibit parametric resonances and anti-resonances affecting the stability of the system. In most cases the destabilizing effect due to parametric resonances is studied. Anti-resonant cases seem to be uninteresting. However, the anti-resonances have an interesting property of introducing additional artificial damping to the system, thus improving its stability and reducing the vibration amplitude. Apart from different control applications, this stabilizing effect may be interesting for its probable ability to indicate the shaft crack. The possible application of the additional damping introduced by parametric excitation for the shaft crack detection is analyzed in the present paper.
The approach is demonstrated with a mathematical model of a rotor with a cracked shaft. The stability analysis of the rotor is performed analytically by employing the averaging method. Stability boundaries for different frequencies of the parametric excitation and for different crack depths are derived. The results of this analysis are checked numerically by means of the Floquet’s theory. Next, possible applications of the parametric excitation for the shaft crack detection are validated numerically. The results demonstrate the potential of the suggested approach, yet further analytical and experimental studies are required.
Experimental Analysis of Rotating Instability Using Hot Wire Triggered PIV and Wavelet Transform
Authors: Hermle Georg , Lawerenz Martin 
Published: September 2014

The authors present initial results of hot wire anemometry triggered PIV measurements of periodic effects in an annular compressor cascade. The investigations are focused on the unsteady effect of a rotating instability (RI) and are based on PIV measurements performed within the passage of a highly loaded annular compressor cascade. Simultaneously, hot wire measurements were conducted within the same passage. Post-processing the hot wire signal by means of the wavelet transform obtained the time resolved frequency spectrum as well as the time resolved phase angles. Such spectra allow filtering the PIV results to select only the results that feature the investigated effect of PI. The corresponding phase angles of the wavelet transform enable grouping the selected PIV results in phase classes. The average of each class gives the statistical mean flow field for the corresponding phase angle. Afterwards, the statistical mean period of the RI can be displayed by discrete ensemble averaged PIV results.
The presented method improves the possible temporal resolution of PIV systems beyond their technical sampling rate. In the case presented, the statistical method leads to a temporal resolution corresponding to a sampling rate of 1.5 kHz, whereas the effective sampling rate of the PIV system used is 4 Hz. The possible resolution in time is only limited by the number of phase classes and accordingly by the number of PIV measurements.
Dependence of External Heat Transfer Coefficient and Aerodynamics on Wall Temperature for 3-D Turbine Blade Passage
Authors: Maffulli R. , He L. 
Published: September 2014

The dependency of convective heat transfer coefficient (HTC) on wall temperature has been recognized in some previous works but existing corrections are confined to either empirically based correlations or based on a boundary layer approach. A recent study by the present authors on a 2D configuration highlights upstream flow history has a strong impact on HTC for a non-adiabatic blade surface, and such an effect cannot be adequately corrected by the use of existing empirical correlations. A boundary layer based approach may be used in a 2D case for the correction as attempted previously. However, it is strongly argued that a boundary layer based method would become very difficult, if not impossible, to apply for complex 3D flows as those in endwall and secondary flow regions of a turbine blade passage.
The present work is aimed to examine how the HTC and main 3D passage aerodynamic features of interest may be affected by the wall temperature condition. A systematic computational study has been firstly carried out for a 3D NGV passage. The impacts of wall temperature on the secondary flows, trailing edge shock waves and the passage flow capacity are discussed, underlining the connection and interactions between the wall temperature and the external aerodynamics of the 3D passage. The local errors in HTC in these 3D flow regions can be as high as 30–40% if the wall temperature dependence is not corrected.
The effort is then directed to a new 3-point non-linear correction method. The benefit of the 3-point method in reducing errors in HTC is clearly demonstrated. A further study illustrates that the new method also offers much enhanced robustness in the HTC procedure, particularly relevant when the wall thermal condition is shown to influence the laminar-turbulent transition as exhibited by two well-established transition models adopted in the present work.
Endwall Film Cooling Using the Staggered Combustor-Turbine Gap Leakage Flow
Authors: Zhang Yang , Yuan Xin 
Published: September 2014

A key technology of gas turbine performance improvement was the increase in the turbine inlet temperature, which brought high thermal loads to the Nozzle Guide Vane (NGV) components. Strong pressure gradients in the NGVs and the complex secondary flow field had made thermal protection more challenging. As for the endwall surface near the pressure side gill region, the relatively higher local pressure and cross flow apparently decreased the film-cooling effectiveness. The aim of this investigation was to evaluate a new design, improving the film-cooling performance in a cooling blind area with upstream staggered slot, simulating the combustor-turbine leakage gap flow. The test cascades model was manufactured according to the GE-E3 nozzle guide vane scaled model, with a scale ratio of 2.2. The experiment was performed under the inlet Mach number 0.1 and the Reynolds number 3.5×105 based on an axial chord length of 78 mm. The staggered slots were positioned upstream of the cascades to simulate the combustor-turbine gap leakage. The Pressure Sensitive Painting (PSP) technique was used to detect the film cooling effectiveness distribution on the endwall surface.
Through the investigation, the following results could be achieved: 1) the film-cooling effectiveness on the endwall surface downstream the slot and along the pitchwise direction increased, with the highest parameter at Z/Pitch = 0.6; 2) a larger cooled region developed towards the suction side as the blowing ratio increased; 3) the advantage of the staggered slot was apparent on the endwall surface near the inlet area, while the coolant film was obviously weakened along the axial chord at a low blowing ratio. The influence of the staggered slots could only be detected in the downstream area of the endwall surface at the higher blowing ratio.
Thermo-Economic Optimization of an Integrated Solar Combined Cycle
Authors: Fusaro Francesco , Conte Enrico , Baykal Sevket , Pattacini Marco 
Published: September 2014

If compared to a conventional combined cycle, the optimal design of an Integrated Solar Combined Cycle (ISCC) requires the consideration of additional design parameters, such as the optimal integration point of the solar steam import in the combined cycle, the solar steam generator rating or the size of the solar field. Moreover, to identify the optimal design over the entire operating profile, the trade-off between amount of solar steam generation capacity and the (over)sizing of key components like HRSG, steam turbine, and condenser needs to be considered.
Alstom is prepared to integrate its proprietary technologies in an ISCC. Taking on the above challenge while providing the best possible value to customers calls for advanced methodologies for the selection of the design parameters.
This paper presents a methodology for the initial design of an ISCC, which through determination of the plant thermo-economic performance for a given set of technical and economical boundary conditions, as well as under consideration of the plant’s operating profile, allows identifying the ISCC design with the highest return on investment.
The additional capabilities implemented in the latest development of Alstom’s in-house plant optimization toolbox show that choice of the operating regimes has a strong effect on customer investment strategy.
This confirms that availability of an optimization tool allowing a systematic identification of the right ISCC configuration for the given project specific constraints, is vital.
This tool development handles the critical design parameters with the required accuracy, thus enabling to match the ISCC design with the operational, economical, and physical boundaries of an ISCC project. Furthermore, the tool allows to carry out sensitivity studies and to prioritize development efforts.
Experimental and Numerical Investigations on Basic Characteristics of High-Performance Abradable-Aero Hybrid Seal
Authors: Kuwamura Yoshihiro , Matsumoto Kazuyuki , Uehara Hidekazu , Ooyama Hiroharu , Tanaka Yoshinori , Nishimoto Shin 
Published: September 2014

As key technologies to improve the performance of steam turbines, various types of high performance seal, such as active clearance control (ACC) seals and leaf seals [1], have been developed by Mitsubishi Heavy Industries, LTD (MHI). In recent years, a new seal concept using an aerodynamic approach called “aero seal” has also been developed, which remarkably reduces the leakage flow while maintaining fin clearances. Furthermore, more robust and higher performance sealing technology called “abradable-aero hybrid seal” which combines the aero seal concept with the abradable seal technology was proposed.
The main concept of the aero seal is to control and utilize the vortex structure in the cavities of the labyrinth seal. In the cavities of the aero seal, the locally-controlled flow on the upstream side of the fin tip causes a strong contraction of the leakage flow and reduces the discharge coefficient significantly. This concept allows for a remarkably reduced leakage flow while maintaining fin clearances. Moreover, in order to achieve more robust and higher performance by minimizing the fin clearances, the abradable seal technology was applied to the aero seal concept. However, when the abradable seal is applied, the grooves may be formed on the wall surface of the abradable material due to rubbing of the fin into the abradable material. This situation leads to concern that the groove breaks the effective vortex structure of aero seal and causes negative effects on the seal performance.
In this paper, the improved aero seal configuration consisting of slant fins was proposed and it was verified that the reduction in the discharge coefficient of improved aero seal is up to 40% compared to the conventional labyrinth seal. Furthermore, more robust and higher performance sealing technology called “abradable-aero hybrid seal” was proposed and basic characteristics such as the effects of the presence of grooves, the axial position of the fin and seal clearance on the leakage mass flow and the vortex structure were parametrically investigated both experimentally and numerically. In the experiments, not only leakage mass flow measurements but also PIV measurements were carried out in order to visualize the flow patterns in the cavity of the abradable-aero hybrid seal. From the results, it was confirmed that the effective vortex structures were formed even with grooves at various fin positions and the leakage flow can be stably reduced over 40% in a wide range of axial position and reduced by 50% at the optimum position.