bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis and Design of Centrifugal Blowers for the Pressure Ratio Range 1.2 - 1.8
Authors: Howard Jonathon , Engeda Abraham 
Published: September 2021

Abstract
Centrifugal/centrifugal compressor designs within pressure ratio range of 2.0–4.0 have well-established guidelines for most common gases, and it is possible to determine optimum compressor geometry for numerous applications as characterized by specific speed or flow coefficient. Specific speed can be correlated to various combinations of inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, blade exit back-sweep, and inlet-tip absolute tangential velocity for solid body pre-whirl. For centrifugal compressors in the pressure ratio range of 1.2–1.8, commonly known as blowers, there lacks organized and systematic optimum design procedures.
Blowers, among many others uses, are widely used in HVAC, and provide air for ventilation and industrial process requirements. Due to broad applications in industry, blowers comprise an important sub-group of turbomachinery. This paper provides analysis and design data for blowers in the pressure ratio range of 1.2–1.8. Specific speed is determined from the data provided, and accurate correlations to possible achievable maximum efficiencies are established within a good operational range. Furthermore, plots of impeller exit flow angle, inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, head coefficient, and blade exit back-sweep are provided over a range of specific speeds for various tip speeds to permit rapid selection of optimum blower size and shape for a variety of applications. The design procedure follows a method that enables efficient blade passage sizing. When the blower inlet and outlet velocities, diameters, blade widths, and blade angles are determined and fixed, the blade passage and profile will be sized by applying an energy, momentum, and continuity balance analysis. The application of these equations equates the proper pressure and velocity distribution throughout the blower impeller. Generally, the passage is designed to accommodate an optimum prescribed diffusion rate.
Coupling of Mainstream Velocity Fluctuations With Plenum Fed Film Cooling Jets
Authors: Sperling Spencer , Christensen Louis , Celestina Richard , Mathison Randall , Aksoy Hakan , Liu Jong , Nickol Jeremy 
Published: September 2021

Abstract
Modern gas turbine engines require film cooling to meet efficiency requirements. An integral part of the design process is the numerical simulation of the heat transfer to film cooled components and the resulting metal temperature. Industry design simulations are frequently performed using steady Reynolds averaged Navier-Stokes (RANS) simulations. However, much research has shown limitations in the use of steady RANS to predict film cooling performance. Prediction errors are typically attributed to poor modelling of turbulent mixing. Recent experiments measuring time-accurate film cooling jet behavior have indicated unsteady jet motions in sweeping and separation-reattachment modes contribute to the dispersion of the cooling jet along the cooled surface and the resulting time-averaged distribution. This study identifies the physical phenomena acting on film cooling jets issuing from fan-shaped film cooling holes, including acoustic resonance, which drive the unsteady behavior. Turbulent velocity fluctuations in the stream-wise direction cause corresponding fluctuations in the film cooling jet blowing ratio, which in turn reduces the time-averaged film cooling performance compared to the steady behavior that would be predicted with time-averaged blowing ratio.
The plenum film cooling supply geometry acts as a Helmholtz resonator. An unsteady RANS (URANS) simulation including unsteady forcing is compared to experimental data. Helmholtz frequency excitation causes film cooling jet motions that qualitatively match the experiment. Resonant behavior causes the periods of lower blowing ratio to contribute to coolant dissipation rather than increased surface coverage.
Results from URANS simulations demonstrate that replicating the unsteady jet motion is an important step in film cooling predictions. Starting with a steady baseline prediction, the URANS model used in this study is observed to reduce the overprediction of lateral average effectiveness by more than 50%, underlining the advantages of modeling the unsteady components of the Navier-Stokes equations.
Performance Modification of an Erosion-Damaged Large-Sized Centrifugal Fan
Authors: Aldi Nicola , Casari Nicola , Pinelli Michele , Suman Alessio , Vulpio Alessandro , Saccenti Paolo 
Published: September 2021

Abstract
Heavy-duty fans are frequently employed in industrial processes that involve the operation of contaminated gases. Particle-laden flows may cause erosion issues, generating several drawbacks such as unbalanced load, vibrations and structural damage responsible for performance degradation and early failure. In this paper, the erosion behavior of a large-sized centrifugal fan employed in clinker production is studied by numerical simulation. Based on preliminary numerical results for the undamaged fan configuration and on-field erosion detections, the geometry damage effects due to the erosion process are analyzed. The severe erosive conditions under which these machines operate determine a progressive reduction in wall thickness of specific fan zones, which may finally result in the formation of holes. This, in turn, makes the internal flow field changing, affecting contaminant trajectories and impact characteristics. CFD predictions show that erosion-induced damage on the fan inlet cone causes a distortion of the velocity profile immediately upstream of the impeller, which influences the impeller flow. Simultaneously, the erosion process changes, leading to a modification of particle impact areas, impact kinematic characteristics and erosion intensity. This investigation focuses on the importance of erosion predictions for maintenance planning and scheduling and demonstrates how localized damage could be responsible for larger damage, involving the structural integrity of the installation.
An Experimental Investigation Into the Impacts of Varying the Circumferential Extent of Tip-Low Total Pressure Distortion on Fan Stability
Authors: Allen Oliver , Castillo Pardo Alejandro , Hall Cesare A. 
Published: September 2021

Abstract
Future jet engines with shorter and thinner intakes present a greater risk of intake separation. This leads to a complex tip-low total pressure distortion pattern of varying circumferential extent. In this paper, an experimental study has been completed to determine the impact of such distortion patterns on the operating range and stalling behaviour of a low-speed fan rig. Unsteady casing static pressure measurements have been made during stall events in 11 circumferential extents of tip-low distortion. The performance has been measured and detailed area traverses have been performed at rotor inlet and outlet in 3 of these cases — clean, axisymmetric tip-low and half-annulus tip-low distortion. Axisymmetric tip-low distortion is found to reduce stall margin by 8%. It does not change the stalling mechanism compared to clean inflow. In both cases, high incidence at the tip combined with growth of the casing boundary layer drive instability. In contrast, half-annulus tip-low distortion is found to reduce stall margin by only 4% through a different mechanism. The distortion causes disturbances in the measured casing pressure signals to grow circumferentially in regions of high incidence. Stall occurs when these disturbances do not decay fully in the undistorted region. As the extent of the distorted sector is increased, the stability margin is found to reduce continuously. However, the maximum disturbance size before stall inception is found to occur at intermediate values of distorted sector extent. This corresponds to distortion patterns that provide sufficient circumferential length of undistorted region for disturbances to decay fully before they return to the distorted sector. It is found that as the extent of the tip-low distortion sector is increased, the circumferential size of the stall cell that develops is reduced. However, its speed is found to remain approximately constant at 50% of the rotor blade speed.
A Computational Fluid Dynamics (CFD) Guided Engineering Solution for Performance Improvement of a Multistage Pump
Authors: Javaherchi Teymour , Brahmeshwarkar Susheel , Faruq Raja , Deshpande Chinmay 
Published: September 2021

Abstract
This work will demonstrate how the Energy Recovery Inc. (ERI) engineering team improved the efficiency of a multistage pump by about 10% at the first stage, which translated into a 3% increase in the overall multistage pump efficiency; according to a set of engineering calculations and review of the archived in-house test data for the legacy multistage pumps, it was hypothesized that the performance pain-point of the pump was inefficient performance of the first stage, due to the formation of a strong pre-swirl right before its inlet. The validity of this hypothesis then was confirmed via RANS CFD simulations of the flow field inside the inlet suction housing and pump impeller. Same CFD methodology was used to evaluate multiple engineering solutions to reduce the strength of the inflow pre-swirl by modifying the inlet suction housing geometry. The obtained RANS CFD solutions guided the engineering team towards the most promising hardware modification proposal. The proposed geometrical modification of the inlet suction housing was implemented and tested on different multistage pumps. All of the test results validated the obtained RANS CFD numerical solution.
The state of the art in this successful performance improvement process was first the on-point hypothesis development based on fundamentals of engineering and archived test data. Second, the proper RANS CFD methodology development to model/confirm the initial hypothesis and vet all possible engineering solutions to maximize the multistage pump efficiently and accurately. This can be a great example for various relevant turbomachinery industrial applications.
Data-Driven Approach for Identifying Mistuning in As-Manufactured Blisks
Authors: Kelly Sean T. , Lupini Andrea , Epureanu Bogdan I. 
Published: September 2021

Abstract
Sector-to-sector geometry or material property variations in as-manufactured bladed disks, or blisks, can result in significantly greater vibration responses during operation compared to nominally cyclic symmetric designs. The dynamics of blisks are sensitive to these unavoidable deviations, known as mistuning, making the identification of mistuning in as-manufactured blisks necessary for accurately predicting their vibration. As in previous mistuning modeling and identification approaches, the mistuning of interest is small and is parameterized by using deviations in cantilever blade-alone frequencies. Such mistuning parameterization is popular because it can be applied through blade-to-blade stiffness deviations in computational reduced-order models used to predict blisk dynamics. Previous approaches to identify such mistuning parameters often require the identification of modal information or blade-isolation techniques such blade detuning using masses or adding damping pads. However, modal information can be difficult to obtain accurately even in optimal bench conditions. Additionally, in practice it can be difficult to isolate individual blades by restricting blade motion around the blisk or detuning individual blades through added masses due to geometric constraints. In this paper, we present a method for mistuning identification using a data-driven approach based on a neural network. The network is first trained using surrogate computational data. Thus, the data-driven portion of the approach is executed using surrogate computational methods. With the trained network, mistuning in all sectors of blisks with the same nominal geometry can be identified by using a small number of forced responses and the forcing phase information from traveling-wave excitation. In this approach, no system or sector-level modal response information, restrictive blade isolation, or mass detuning are required. We additionally present a method for forcing frequency selection and response conditioning to improve identification accuracy. Validation of this approach is presented using a finite element blisk model containing stiffness mistuning within the blades to create computationally generated surrogate data. It is shown that mistuning can be predicted accurately using forced responses containing a significant amount of absolute and relative measurement noise, mimicking responses collected from experimental measurements. In addition, it is shown that mistuning can be predicted independently and accurately using different engine orders of excitation in regions of high modal density.
Application of a Viscous Through-Flow Model to a Modern Axial Low-Pressure Compressor
Authors: Budo Arnaud , Terrapon Vincent E. , Arnst Maarten , Hillewaert Koen , Mouriaux Sophie , Rodriguez Benoit , Bartholet Jules 
Published: September 2021

Abstract
This paper describes the evaluation of a newly developed viscous time-marching through-flow solver to two test cases to assess the applicability of the method using correlations from the literature to modern blade designs. The test cases are the classic axial compressor stage CME2 and a modern highly loaded multi-stage axial low-pressure compressor developed by Safran Aero Boosters. The through-flow solver is based on the Navier-Stokes equations and uses a pseudo-time marching method. The closure models currently include terms of major importance: the blade forces and the Reynolds stress. The results are compared to higher-fidelity results including three-dimensional RANS simulations to assess their reliability for design and off-design conditions. The main originality of this work is the evaluation of the CFD-based method in the context of a compressor with highly three-dimensional blades, as such an analysis is not commonly found in the literature.
The solver gives realistic predictions of loss and deviation for the compressor stage CME2 at both design and off-design operating conditions. Regarding the second test case, the through-flow simulations based on theoretically non-adapted correlations for such a compressor are still in good agreement with RANS simulations, although the results for the 2nd test case are probably not as good as for the first. These results are a promising first step towards the use of this through-flow model for industrial design. Regarding the ongoing closure models development, suggestions to extend the loss models to a larger range of designs are discussed.
Searching for the Optimal Arrangement of Mistuned Blades Based on Solving the Traveling Salesman Problem for Simple Mass-Spring Linear System
Authors: Serebriakov Nikolay , Selivanov Alexander 
Published: September 2021

Abstract
The article presents an approach to finding the optimal arrangement of blades in a bladed disk based on solving the traveling salesman problem using the ant colony algorithm. The solution to the problem is presented for an equivalent model of the bladed disk. The mistuning parameters are assumed as known — for example, from the data of geometric measurements for each blade from the set used for assembling the bladed disk — considering the influence of the rotation on the investigated resonance mode.
Approaches have already been published for the construction of equivalent models and the use of combinatorial optimization methods, including solving the traveling salesman problem, to find the optimal arrangement of the blades. Therefore, this article focuses on demonstrating a simple program implementation of this method.
This approach allows a quick assessment of the effect of the blade assembly in the bladed disk on the amplitudes of alternating stresses. It even considers several restarts of the algorithm to determine other possible configurations of the system.
Modelling Conjugate Heat Transfer Within a Gas Turbine Secondary Air System Using 1D and 2-3D Solid Models in Thermo-Fluid System Simulation
Authors: Hunt David , Yuan Youming , Gardner Ian 
Published: September 2021

Abstract
This paper presents an implicit conjugate heat transfer (CHT) model designed for 1D systems of both solids and fluids. It demonstrates that this approach can be extended to include 2D and 3D elements being co-solved in a 2D or 3D thermal product. The approach is applied to a simple analytical problem and then to a Secondary Air Cavity within a Gas Turbine to illustrate the potential of this technique to be applied to more complex thermo-fluid simulations. Such simulations are important in trade off studies to balance minimizing engine bleed whilst ensuring sufficient cooling. The benefits of this CHT model are presented by comparison with the traditional approach of explicit co-simulation in which the temperature from the fluid domain is applied as a boundary condition to the thermal simulation and heat flux from the thermal simulation is applied as a boundary condition to the fluid domain (or vice versa). The ability to replace 1D elements with 2D or 3D elements allows model continuity from conceptual to detailed design and the reverse process potentially offers a route for model reduction later in lifecycle to support operation and maintenance through the use of an executable digital twin.
Approximation Method of the Gas Turbine Engine Compressor Characteristics
Authors: Avdeev Sergey , Tkachenko Andrey 
Published: September 2021

Abstract
A technique of representing and approximating of gas turbine engine (GTE) compressor maps is given. The aims of this study are to improve the efficiency of processing GTE test results and the reliability of GTE mathematical model.
The paper analyzes various approaches of approximating, presenting, and generalizing the characteristics of compressors. The advantages and limitations of the existing compressor maps approximation methods are summarized in the paper. A comparison of the obtained approximating method is carried out against previously developed methods.
Based on the performed analysis, a method is proposed for approximating of compressor maps, considering the requirements of identification of the GTE model. The resulting approximation method is based on the use of equations in a polar coordinate system. The study also analyzed the possibility of using the developed method in the system of thermodynamic calculations and analysis “ASTRA” (the program was developed at Samara University).
The developed approximation technique was tested on the experimental characteristics of the low- and high-pressure axial compressor. The estimation of the quality of the approximation was carried out using the standard deviation. It has been demonstrated that the obtained approximating functions describe the experimental data quite well. The obtained values of the standard deviation in the polar coordinate system were less than 10%.
Survey of Calculation Methods for Polytropic Efficiencies
Authors: Wettstein Hans E. 
Published: September 2021

Abstract
Calculating polytropic efficiencies is a basic task used for quantifying performance of power cycles involving compression and/or expansion. The incremental definition of a “polytropic curve” of gases by Gustav Zeuner in 1905 may be the oldest mention of the word “polytropic” in a thermodynamic context [1].
In Turbomachinery blading, the typical changes of state are nearly adiabatic and polytropic. L. S. Dzung was probably the first defining an incremental polytropic efficiency in 1944 [3]. Recursive integration of this has become the best thermodynamic quality measure of a blading.
Both Zeuner and Dzung started their consideration with an incremental definition. However, they integrated analytically assuming ideal gas data. This resulted in the well-known formula (1) p v n = constant Most thermodynamic textbooks declare this the definition of a polytropic change of state. However, the incremental definition survived too. Stodola [2], Dzung and later scientists established it as another definition of a polytropic change of state.
Thus, we face now two definitions of a polytropic change of state, which are theoretically identical for ideal gases but different for real gases and vapors. In educational context, this is disturbing and forcing to a logical detour. We trace the historic roots and show that the initial incremental definition is the physically healthier one. Recursive integration allows direct application to turbomachinery with any finite pressure ratio and to any real fluid.
Multi-Parameter Optimization to Improve the Erosion Resistance of Coating by FE Simulation
Authors: Li Fang , Wang Shunsen , Cai Liuxi , Feng Zhenping 
Published: September 2021

Abstract
Finite element method (FEM) was used to study the stress peak of stress S11 (Radial stress component in X-axis) on the steam turbine blade surface of four typical erosion-resistant coatings (Fe2B, CrN, Cr3C2-NiCr and Al2O3-13%TiO2). The effect of four parameters, such as impact velocity, coating thickness, Young’s modulus and Poisson’s ratio on the stress peak of stress S11 were analyzed. Results show that: the position of tensile stress peak and compressive stress peak of stress S11 are far away from the impact center point with the increase of impact velocity. When coating thickness is equal to or greater than 10μm, the magnitude of tensile stress peak of stress S11 on the four coating surfaces does not change with the coating thickness at different impact velocities. When coating thickness is equal to or greater than 2μm, the magnitude of tensile stress peak of stress S11 of four coatings show a trend of increasing first and then decreasing with the increase of Young’s modulus. Meanwhile, the larger the Poisson’s ratio, the smaller the tensile stress peak of stress S11. After optimization, When coating thickness is 2μm, Poisson’s ratio is 0.35 and Young’s modulus is 800 GPa, the Fe2B coating has the strongest erosion resistance under the same impact conditions, followed by Cr3C2-NiCr, CrN, and the Al2O3-13%TiO2 coating, Al2O3-13%TiO2 coating has the worst erosion resistance.
Centrifugal Compressor Stage Efficiency and Rotor Stiffness Augmentation via Artificial Neural Networks
Authors: Agnolucci Andrea , Marconcini Michele , Arnone Andrea , Toni Lorenzo , Grimaldi Angelo , Giachi Marco 
Published: September 2021

Abstract
Centrifugal compressor stages with high rotor stiffness (i.e. impeller hub-to-outer-diameter ratio) may represent a crucial element to cope with tight rotordynamic requirements and constraints that are needed for certain applications. On the other hand, high-stiffness has a detrimental effect on the aerodynamic performance. Thus, an accurate design and optimization are required to minimize the performance gap with respect to low-stiffness stages. This paper shows a redesign and optimization procedure of a centrifugal compressor stage aimed at increasing the impeller stiffness while keeping high aerodynamic performance. Two different optimization steps are employed to consider a wide design space while keeping the computational cost as low as possible. At first the attention is focused on the impeller only, then the diffuser and the return channel are taken into account. The multi-objective and multi-operating point optimization makes use of artificial neural networks (ANNs) as a surrogate model to obtain the response surfaces. RANS calculations are carried out using the TRAF code and are employed to create the training dataset. Once the ANN has been trained, an optimization strategy is used to find the constrained optimum geometries for the impeller and the static components. The optimized high-stiffness stage is finally compared to the low-stiffness one to assess its applicability.