bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary Design Tool for Centrifugal Compressors
Authors: Baye-Wallace Lily , Musgrove Grant O. 
Published: September 2021

Abstract
Commonly, compressor designs rely on previous machines that can be slightly modified to achieve new operating requirements. In some cases, however, a completely new design is needed because no previous designs are available for the specific operating range of interest. Without a previous design, it is difficult to make initial trade studies of an appropriate impeller diameter, speed, and number of compression stages. While new compressor designs are a common occurrence in applied research applications, conceptual design typically require a point-by-point process to balance the requirements with acceptable design parameters. This can be done manually or through automation to optimize for a specific operating parameter, such as efficiency. The authors are unaware of any tool available that bounds the range of design parameters for a centrifugal compressor stage without applying a point-by-point method. In this work, two common references for conceptual compressor design were cross-checked to develop an Excel-based tool to quickly determine the design space for a given set of compressor requirements.
The tool relies on design experience presented by Aungier and Baljé as well as other experience drawn from available literature [1],[2]. The sheet functions from a series of assumptions based within the design experience and requires inputs regarding the desired power, fluid flow rate, and total-to-total pressure ratio, as well as inlet conditions. While the tool currently assumes an ideal gas, future revisions can include calls to REFPROP for a real gas.
Numerical Simulation on the Vortex Shedding From Airfoils of a Swirl Distortion Generator
Authors: Hayden Andrew , Hefner Cole , Untaroiu Alexandrina , Gillespie John , Lowe K. Todd 
Published: September 2021

Abstract
The StreamVane™ swirl distortion generator, developed by Virginia Tech, can efficiently reproduce the boundary layer of an airframe or duct found in boundary layer ingesting (BLI) aircraft. Due to manufacturing limitations, the vanes within StreamVanes induce unsteady, vortical wakes, commonly known as a von Karman vortex street. This paper investigates the use of a commercial URANS code and SST turbulence model to predict the vortex shedding frequency from the vanes. The objective was accomplished in two main tasks. First, the CFD methodology was validated by modeling the fluid dynamics of a linear cascade experiment done by the von Karman Institute. Second, the same methodology was applied to airfoils used in StreamVane design to calculate the shedding frequency as a function of turning angle and TE thickness. It was predicted that an increase in turning angle exponentially increased the shedding frequency while an increase in TE thickness exponentially decreased the shedding frequency. The results provided a correlation between the shedding frequency and airfoil characteristics in StreamVanes as well as various turbomachinery components.
Extending a Van der Pol Based Reduced-Order Model for Fluid-Structure Interaction Applied to Non-Synchronous Vibrations in Turbomachinery
Authors: Hollenbach Richard , Kielb Robert , Hall Kenneth 
Published: September 2021

Abstract
This paper expands upon a multi-degree-of-freedom, Van der Pol oscillator used to model buffet and Nonsynchronous Vibrations (NSV) in turbines. Two degrees-of-freedom are used, a fluid tracking variable incorporating a Van der Pol oscillator and a classic spring, mass, damper mounted cylinder variable; thus, this model is one of fluid-structure interaction. This model has been previously shown to exhibit the two main aspects of NSV. The first is the lock-in or entrainment phenomenon of the fluid shedding frequency jumping onto the natural frequency of the oscillator, while the second is a stable limit cycle oscillation (LCO) once the transient solution disappears. Improvements are made to the previous model to better understand this aeroelastic phenomenon. First, an error minimizing technique through a system identification method is used to tune the coefficients in the Reduced Order Model (ROM) to improve the accuracy in comparison to experimental data. Secondly, a cubic stiffness term is added to the fluid equation; this term is often seen in the Duffing Oscillator equation, which allows this ROM to capture the experimental behavior more accurately, seen in previous literature. The finalized model captures the experimental cylinder data found in literature much better than the previous model. These improvements also open the door for future models, such as that of a pitching airfoil or a turbomachinery blade, to create a preliminary design tool for studying NSV in turbomachinery.
The STEP 10 MWe sCO2 Pilot Demonstration Status Update
Authors: Marion John , Lariviere Brian , McClung Aaron , Mortzheim Jason 
Published: September 2021

Abstract
The Gas Technology Institute (GTI®), Southwest Research Institute® (SwRI®) and General Electric Global Research (GEGR) are executing the “STEP” [Supercritical Transformational Electric Power] project, to design, construct, commission, and operate an integrated and reconfigurable 10 MWe sCO2 [supercritical CO2] pilot plant test facility. The $122* million project is funded $84 million by the US DOE’s National Energy Technology Laboratory (NETL Award Number DE-FE0028979) and $38* million (*including building investment) by the team members, component suppliers and others interested in sCO2 technology. This paper provides an update on the project’s progress. The pilot facility is currently under construction at SwRI’s San Antonio, Texas, USA campus. Now well into Phase 2, a ground-breaking was held in October of 2018, and civil work and the construction of a dedicated 22,000 ft2 building is complete. Most major equipment is in fabrication or delivered to site. Efforts have already provided valuable project learnings for technology commercialization. This project is a significant step toward sCO2 cycle based power generation commercialization and is informing the performance, operability, and scale-up to commercial plants.
High-Fidelity Simulations of a High-Pressure Turbine Stage: Effects of Reynolds Number and Inlet Turbulence
Authors: Zhao Yaomin , Sandberg Richard D. 
Published: September 2021

Abstract
We present the first wall-resolved high-fidelity simulations of high-pressure turbine (HPT) stages at engine-relevant conditions. A series of cases have been performed to investigate the effects of varying Reynolds numbers and inlet turbulence on the aerothermal behavior of the stage. While all of the cases have similar mean pressure distribution, the cases with higher Reynolds number show larger amplitude wall shear stress and enhanced heat fluxes around the vane and rotor blades. Moreover, higher-amplitude turbulence fluctuations at the inlet enhance heat transfer on the pressure-side and induce early transition on the suction-side of the vane, although the rotor blade boundary layers are not significantly affected. In addition to the time-averaged results, phase-lock averaged statistics are also collected to characterize the evolution of the stator wakes in the rotor passages. It is shown that the stretching and deformation of the stator wakes is dominated by the mean flow shear, and their interactions with the rotor blades can significantly intensify the heat transfer on the suction side. For the first time, the recently proposed entropy analysis has been applied to phase-lock averaged flow fields, which enables a quantitative characterization of the different mechanisms responsible for the unsteady losses of the stages. The results indicate that the losses related to the evolution of the stator wakes is mainly caused by the turbulence production, i.e. the direct interaction between the wake fluctuations and the mean flow shear through the rotor passages.
Turbine Inlet Temperature Measurements in a T 8200 kW Gas Turbine Using Water Vapor Emission
Authors: Tree Dale R. , Badger Dustin , Zeltner Darrel , Rezasoltani Mohsen 
Published: September 2021

Abstract
The measurement of turbine inlet temperature is challenging because of high temperatures and complicated physical access, but continuous measurement of the turbine inlet temperature is very important for maximizing turbine efficiency and increasing durability. This paper provides in-situ turbine rotor inlet temperature (TRIT) measurements in an 8200 kW operating gas turbine engine. The measurements were obtained using integrated spectral infrared (ISIR) emission from the water vapor of the combustion gases entering the turbine rotor. The method utilizes a sapphire optical fiber to convey the signal from the turbine wall to outside the turbine casing. All components are capable of long-term exposure to the turbine operating conditions. The temperature measurements were obtained at 6 operating conditions between 50% and full load. The TRIT temperature was also determined using more than 20 test cell inputs and Solar Turbine’s commercial test cell engine model. The two temperatures (measured and modeled) were within 11 K (less than 1%) across the load sweep. Uncertainty calculations suggest that the uncertainty of the measurement can be expected to be ±2.9% within a confidence interval of 95%. The method also yields the nozzle guide vane surface temperature which was found to increase monotonically with increasing load.
Optimization of Fuel Nozzle Diameter in a Novel Cross Flow Lean Direct Injection Burner
Authors: Chakraborty Kingshuk , Chakravarthy S. R. 
Published: September 2021

Abstract
Lean Direct Injection (LDI) concept proves to be an ultra-low NOx combustion scheme for future gas turbine combustors because of its ability to operate at very lean conditions. For LDI burners, the Fuel Nozzle Diameters (FND) play a vital role in deciding a balance between the various performance criteria demanded by the gas turbine industry like efficient usage of fuel, a wide range of flame stability, uniform exit temperature distribution and very low overall emissions. This paper attempts to find the optimum FND in terms of some key combustion parameters, for a novel multi-swirl LDI burner having a cross-flow mixing between fuel jets and swirling air. At first, lean blow out limits were detected from experiments with different FND using two different fuels, methane and liquefied petroleum gas, within a range of air flow rates. It was observed that with the decrease in FND the flame extinguished at a higher equivalence-ratio. Then their performances were compared through CFD simulations with two different combustion models, namely, Eddy Dissipation and PDF Flamelet. The combined results of cold and hot flow simulations showed that with the decrease in FND the fuel jet was able to penetrate deeper into the air swirl by overcoming the air momentum, which resulted in enhanced mixing leading to more efficient utilization of fuel and also uniform exit temperature distribution resulting in lower pattern factor. Thus the findings of this research work should be resourceful in the development of modern cross-flow LDI combustors.
Film Cooling Effectiveness Measurement of Fan-Shaped Holes Manufactured Using EDM Technique
Authors: Rouina S. , Abdeh H. , Barigozzi G. , Odemondo V. , Abba L. , Iannone M. 
Published: September 2021

Abstract
In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (α), and lateral expansion angle (β) on film cooling effectiveness of holes made using EDM is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant to mainstream blowing ratio (M). The considered flat plate model incorporates engine sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the Pressure Sensitive Paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on β is prescribed. An accurate qualification of hole morphology is also recommended.
Practical Method for Burner Staging Turbine Forced Response Evaluation
Authors: Kafedzhiyski Nikola , Mayorca Maria 
Published: September 2021

Abstract
Decarbonization and sustainability efforts challenge gas turbine engineers to come up with creative strategies for reduction of emissions and efficiency increase over the whole operating range. Burner staging at part loads presents a flexible solution to achieve these goals through selective burner deactivation. Shutting off burners could also be required for combustion of increased H2 content at some conditions. Burner staging will create circumferential unevenness with patterns of hot and cold streaks that could excite blade rows through the entire turbine. This paper presents a parametric method for annular combustor staging patterns profile generation intended for use for forced response predictions from a limited number of combustor CFD calculations while keeping the key phenomenological features. Two cases with burner staging turbine inlet temperature distributions are considered and compared to a base case with uniform temperature distribution. The unsteady aerodynamic forcing was obtained from full wheel time marching unsteady computational fluid dynamics calculations. The results show that the hot streaks generate important and noticeable excitation sources. Additionally, the results show that the pattern generator could be used extensively before and after the unsteady calculations phase to minimize the excitation levels and the computational load.
Flow Fields, Emission and Stabilization in Premixed Centrally-Staged Swirl Flames With Different Air Split Ratios
Authors: Su Tong , Lin Yuzhen , Zhang Chi , Han Xiao 
Published: September 2021

Abstract
The flow fields, emission levels, and static stability characteristics were investigated experimentally under various air split ratios (ASR, the ratio of the pilot stage air mass flow rate to the total air mass flow rate) at a fixed equivalence ratio of 0.8 of both main and pilot stages in a premixed centrally-staged swirl flame. The flame structures were captured by a CH* chemiluminescence high-speed camera and the corresponding results were processed by Abel deconvolution. Besides, the flow fields obtained by using planar Particle Image Velocimetry (PIV) technique were combined with flame structures to make a better study on the aerodynamic structures of the centrally-staged swirl flames. The emission levels of NOx and CO were measured by a gas analyzer. The stability boundaries and flame structures at different equivalence ratios under three ASRs were also studied.
It is found that the size of the reacting primary recirculation zone (PRZ) becomes larger as more air is distributed to the pilot stage. This can be explained by the fact that the majority of the pilot fluid participates in the formation of the PRZ and also as a result of a stronger penetrability of the pilot jet. Moreover, the NOx emission levels increase while CO levels decrease, which is because of the longer residence time of the radicals within a larger PRZ and less impingement of the main flame on the combustor liner. Finally, the stability boundary is extended, and the total blowout equivalence ratio was decreased as the air split ratio increases, which demonstrates the flame stabilization effect of the pilot flame. In brief, the above findings can be a help to choose the appropriate air split ratio in the early design stage of the centrally-staged aero-engine combustors.
Development of a Robust Scrubber Level Controller
Authors: Day Carolyn M. , Beck Griffin C. , Schubring Scott A. 
Published: September 2021

Abstract
Gas-liquid scrubbers rely on level control systems (generally consisting of a level indicator, a level controller, and a pneumatic control valve for liquid release) to maintain an appropriate liquid level within the vessel. Scrubbers are often upstream of turbomachinery and failures at the scrubber can cause liquid ingestion or downtime. In natural gas service, these control systems are subject to harsh environments due to the influx of liquid slugs, high-velocity gases, corrosive fluids, vibrations, and a chaotic gas-liquid interface. In these severe conditions, level control system failures are commonplace and lead to safety and environmental hazards, equipment damage, and lost production. A need exists to augment or replace the typical liquid level control system with an alternative solution that is cost-effective, robust, and can operate reliably in the harsh natural gas environment. A project investigated failures related to scrubber level control systems, identified improvements to these systems, developed a prototype level controller, and tested the prototype controller and a variety of commercially available controllers at various conditions that emulated certain field conditions. The results of these tests gave insight into what type of controller may be best suited to the tested conditions and what controller options should be pursued further.
Unsteady Pressure Measurements in a Heated Rotating Cavity
Authors: Jackson Richard W. , Tang Hui , Scobie James A. , Pountney Oliver J. , Sangan Carl M. , Owen J. Michael , Lock Gary D. 
Published: September 2021

Abstract
The flow in the heated rotating cavity of an aero-engine compressor is driven by buoyancy forces, which result in pairs of cyclonic and anticyclonic vortices. The resultant cavity flow field is three-dimensional, unsteady and unstable, which makes it challenging to model the flow and heat transfer. In this paper, properties of the vortex structures are determined from novel unsteady pressure measurements collected on the rotating disc surface over a range of engine-representative parameters. These measurements are the first of their kind with practical significance to the engine designer and for validation of computational fluid dynamics. One cyclonic/anticyclonic vortex pair was detected over the experimental range, despite the measurement of harmonic modes in the frequency spectra at low Rossby numbers. It is shown that these modes were caused by unequal size vortices, with the cyclonic vortex the larger of the pair. The structures slipped relative to the discs at a speed typically around 10% to 15% of that of the rotor, but the speed of precession was often unsteady. The coherency, strength and slip of the vortex pair increased with the buoyancy parameter, due to the stronger buoyancy forces, but they were largely independent of the rotational Reynolds number.
Improved Prediction of Losses With Large Eddy Simulation in a Low-Pressure Turbine
Authors: Miki Kenji , Ameri Ali 
Published: September 2021

Abstract
There is a need to improve predictions of losses resulting from large eddy simulations (LES) of low-pressure turbines (LPT) in gas turbines. This may be done by assessing the accuracy of predictions against validation data and understanding the source of any inaccuracies. LES is a promising approach for capturing the laminar/turbulent transition process in a LPT. In previous studies, the authors utilized LES to model the flow field over a Variable Speed Power Turbine (VSPT) blade and successfully captured characteristic features of separation/reattachment and transition on the suction side at both the cruise (positive incidence) and take-off conditions (negative incidence) and as well, simulated the effect of free-stream turbulence (FST) on those phenomena. The predicted pressure loading profiles agreed well with the experimental data for both a high and a low FST case at a Reynolds number of Reex = 220,000. In this paper, we present wake profiles resulting from computations for a range of FST values. Although the predicted wake profiles for the lowest FST case (Tu = 0.5%) matched the experimental data, at higher FST (Tu = 10–15%,) the wake was wider than the experimentally measured wake and for both cases were displaced laterally when compared to the experimental measurements. In our investigation of the causes of the said discrepancies we have identified important effects which could strongly influence the predicted wake profile. Predicted losses were improved by assuring the validity of the flow solution. This was done by utilizing spectral analysis to scrutinize the dynamic behavior of the wake and determine solution accuracy resulting from low mesh density and low accuracy of convective modeling.
Numerical Methods for Calculating Component Modes for Geometric Mistuning Reduced-Order Models
Authors: Beck Joseph A. , Brown Jeffrey M. , Kaszynski Alex A. , Gillaugh Daniel L. 
Published: September 2021

Abstract
Geometric mistuning models formulated from a component mode synthesis methods often require the calculation of component modes, particularly constraint and fixed interface normal modes, during substructuring. For Integrally Bladed Rotors, these calculations are required for each sector. This paper proposes methods that reuse information garnered from solving the constraint modes of a single sector on the remaining sectors to reduce memory requirements and solution times. A mesh metamorphosis tool is used to ensure finite element models match geometry obtained from a 3D optical scanner. This tool also produces a common mesh pattern from sector-to-sector. This is exploited to produce common permutation matrices and symbolic factorizations of sector stiffness matrices that are proposed for reuse in solving subsequent constraint modes. Furthermore, a drop tolerance is introduced to remove small values during constraint mode calculation to reduce memory requirements. It is proposed to reuse this dropping pattern produced from a single sector on the remaining sectors. Approaches are then extended to a parallel processing scheme to propose effective matrix partitioning methods. Finally, information gathered during the constraint mode calculations are reused during the solution of the fixed interface normal modes to improve solution time. Results show reusing permutation matrices and symbolic factorizations from sector-to-sector improves solution time and introduces no error. Using a drop tolerance is shown to reduce storage requirements of a constraint mode matrix. Additionally, it is shown that reusing the same dropping pattern introduces minimal error without degradation in solution times. Similarly, reusing the information from constraint modes for calculating fixed interface normal modes greatly improves the performance in a shift-and-invert technique for solving eigenvalue problems.