bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study on Overall Cooling Effectiveness of Swirl-Stabilized Model Combustor With Effusion Cooling
Authors: Ji Yongbin , Zhang Liang , Jin Ming , Ge Bing , Zang Shusheng , Xin Jianhua , Wu Weiliang , Li Mingjia , Xu Wenyan 
Published: November 2019

Abstract
Application of effusion cooling or effusion based compound cooling in the state of art gas turbine combustor is more and more common, especially in aero-engines. A linearly arranged planar optically accessible three-nozzle lab scale combustor equipped with perforated testing plate for cooling is designed. Overall cooling effectiveness is experimentally examined as the key indicator of cooling performance at non-reacting flow conditions. Main air is electrically heated to about 573K. Temperature of perforated liner is recorded by the short-wave infra camera with careful calibration. Effect of effusion hole inclination angle is investigated by comparing at forward (30°), normal (90°) and backward (150°) cases. Pressure drop across the nozzle is set to be 3%, 4% and 5% respectively and that is 0–2.5% for the effusion plate. The main purpose of this work is to characterize combustor liner effusion cooling capacity at conjugate heat trasnfer conditions, and backward cooling configuration is firstly investigated.
Results clearly show that effusion cooling behavior is strongly influenced by main swirling flow regime near the combustor liner wall. To be specific, three zones as Corner Recirculation Zone (CRZ), Impinging Zone (IZ) and Developing Zone (DZ) can be divided. IZ is the region which we should treat carefully for liner cooling design because it sustains the highest heat load. Generally, inclined holes perform better cooling characteristics than normal ones. The important observation is that backward injections reveal “anti-impinging” ability, which can enhance the cooling effectiveness in upstream CRZ and IZ greatly with high coolant consumption. The potential drawback is that reverse cooling jets may induce intense interactions with main flow. But it is still a good choice for optimizing combustor effusion cooling, especially in swirling impinging regions.
Improvement of Steam Turbine Blade Foil With Biomimetic Design and its Influence on Aerodynamic Performance
Authors: Wu Fan , Xie Danmei , Zhang Jing , Zhang Hengliang , Wang Chun 
Published: November 2019

Abstract
To improve the steam turbines’ efficiency, researchers have put their efforts on blade foil design. Aiming at improve the aerodynamic performance of steam turbine at low load, this paper will study the effect of blade foil with bionics design on steam turbine aerodynamic performance, based on humpback whale’s fin. This paper mainly discusses a bionic foil design used on steam turbine. There are three main control parameters for each tubercle structure — amplitude, wavelength, and thickness. Taking the axial torque as the decisive consideration data and combining the vorticity diagram to analyze the flow, and on this basis, the influence of the vortex pair on the flow of the turbine blade is studied. The greater the torque, the stronger the function, so the steam turbines’ efficiency is higher.
The flow condition of the optimized blade shape is improved compared to the original blade shape because it fits the blade more closely and the separated flow vortex is suppressed.
Design and Test of a Novel Highly-Loaded Compressor
Authors: Yang Chengwu , Han Ge , Zhao Shengfeng , Lu Xingen , Zhang Yanfeng , Li Ziliang 
Published: November 2019

Abstract
The blades of rear stages in small size core compressors are reduced to shorter than 20 mm or even less due to overall high pressure ratio. The growing of tip clearance-to-blade height ratio of the rear stages enhance the leakage flow and increase the possibility of a strong clearance sensitivity, thus limiting the compressor efficiency and stability. A new concept of compressor, namely diffuser passage compressor (DP), for small size core compressors was introduced. The design aims at making the compressors robust to tip clearance leakage flow by reducing pressure difference between pressure and suction surfaces. To validate the concept, the second stage of a two-stage highly loaded axial compressor was designed with DP rotor according to a diffuser map. The diffuser passage stage has the same inlet condition and loading as the conventional compressor (CNV) stage, of which the work coefficient is around 0.37. The predicted performance and flow field of the DP were compared with the conventional axial compressor in detail. The rig testing was supplemented with the numerical predictions. Results reveal that the throttle characteristic of DP indicates higher pressure rise and the loss reduction in tip clearance is mainly responsible for the performance improvement. For the compressor with DP, the pressure and flow angle are more uniform on exit plane. What’s more, the rotor with diffused passage reveals more robust than the conventional rotor at double clearance gap. Furthermore, the experimental data indicate that DP presents higher pressure rise at design and part speeds. At design speed, the stall margin was extended by 7.25%. Moreover, peak adiabatic efficiency of DP is also higher than that of CNV by about 0.7%.
Analysis of Solid Particle Ingestion and Dynamics in a Turbomachine Using Large-Eddy Simulation
Authors: Martin Benjamin , Thomas Martin , Dombard Jérôme , Duchaine Florent , Gicquel Laurent 
Published: November 2019

Abstract
Erosion of compressor and turbine blades operating in extreme environment fouled with sand particles, ash or soot is a serious problem for gas turbine manufacturers and users. Indeed, operation of a gas turbine engine in such hostile conditions leads to drastic degradation of the aerodynamic performance of the components, mostly through surface roughness modification, tip clearance height increase or blunting of blade leading edges. To evaluate associated risks, the computation of particle trajectories and impacts through multiple turbomachinery stages by Computational Fluid Dynamics (CFD) seems a decent path but remains a challenge. The numerical prediction of complex turbulent flows in compressors and turbines is however necessary in such a context and validations are still required. Recently, Large-Eddy Simulation (LES) has shown promising results for compressor and turbine configurations for a wide range of operating conditions at an acceptable cost. With this in mind, this article presents the assessment of a LES solver able to treat turbomachine configurations to predict solid particle motion. To do so, the governing equations of particle dynamics are introduced using the Lagrangian formalism and are solved to compute locations and conditions of impact, namely particle velocity, angle and radius. The fully unsteady and coupled strategy is applied to blade geometries for studying the main areas and conditions of impacts obtained with LES. For comparison, a one-way coupling computation based on a mean steady flow field where only the Lagrangian particles are advanced in time is performed to evaluate the gain and drawbacks of both methods.
Deficiencies in Turbulence Modelling for the Prediction of the Stability Boundary in Highly Loaded Compressors
Authors: Moreno Jose , Dodds John , Vahdati Mehdi , Stapelfeldt Sina 
Published: November 2019

Abstract
Reynolds-averaged Navier-Stokes (RANS) equations are employed for aerodynamic and aeroelastic modelling in axial compressors. Their solutions are highly dependent on the turbulence models for closure. The main objective of this work is to assess the widely used Spalart-Allmaras model’s suitability for compressor flows. For this purpose, an extensive investigation of the sources of uncertainties in a high-speed multi-stage compressor rig was carried out. The grid resolution near the casing end wall, which affects the tip leakage flow and casing boundary layer, was found to have a major effect on the stability limit prediction. Refinements in this region led to a stall margin loss prediction. It was found that this loss was exclusively due to the destruction term in the SA model.
Validation of Fracture Prediction Model to Design CMC Turbine Vane
Authors: Sato Hayao , Ueda Yusuke , Andoh Masaharu , Honda Tatsuhito 
Published: November 2019

Abstract
Ceramics matrix composites (CMCs) have higher heat resistance and specific strength than conventional metal. These effects can contribute to not only reducing cooling air and parts weight, but also increasing turbine inlet temperature (TIT). As a result, CMCs have potential to improve aero-engine performance and reducing emission. CMCs also have complicated material characteristics to apply aero engine turbine parts. Stress-strain curve shows not only non-liner behavior in higher stress level but also anisotropy. The behavior and fracture toughness show the anisotropy because of material internal structure. Material strengths indicate anisotropy as well. Low cycle fatigue (LCF) strength indicates dependency of stress gradient. Thus, conventional design methods using linear elastic analysis model and peak stress assessment are too conservative to design CMC parts. IHI is developing SiC-SiC 3D woven fabric which is used for aero engine turbine vane and also building up a fracture prediction model to design the CMC turbine vane. Fracture prediction model is composed of structural analysis model to estimate deformation and fracture evaluation model to predict strength. The material model is assumed as a homogeneous substance and this material model constitutive equation is constructed from the theory of continuum damage mechanics (TCDM). In fracture model, that strength parameter is calculated with averaging stress fields. Multi-axial stress fields are evaluated by engineering equations referred to Hashin’s criteria. To validate our fracture prediction model, specific structural feature test were conducted. Sub-component tests were based on the building block approach that was general to validate structural reliability of composite material parts. Static tests and low cycle and high cycle fatigue tests were carried out at room temperature and high temperature. The validation test results showed good agreement with prediction. Finally we have made sure the validation of this fracture prediction model.
Surrogate Estimations of Complete Flow Fields of Fan Stage Designs via Deep Neural Networks
Authors: Aulich Marcel , Küppers Fabian , Schmitz Andreas , Voß Christian 
Published: November 2019

Abstract
This paper presents a first step to adapt deep neural networks (DNN) to turbomachinery designs. It is demonstrated that DNNs can predict complete flow solutions, using xyzcoordinates of the CFD mesh, rotational speed and boundary conditions as input to predict the velocities, pressure and density in the flow field.
The presented DNN is trained by only twenty random 3D fan stage designs (training members). These designs were part of the initialization process of a previous optimization. The approximation quality of the DNN is validated on a random and a Pareto optimal design. The random design is a statistical outlier with low efficiency while the Pareto optimal design dominates the training members in terms of efficiency. So both test members require some extrapolation quality of the DNN. The DNN reproduces characteristics of the flow of both designs, showing its capability of generalization and potential for future applications.
The paper begins with an explanation of the DNN concept, which is based on convolutional layers. Based on the working principal of these layers a conversion of a CFD mesh to a suitable DNN input is derived. This conversion ensures that the DNNs can work in a similar way as in image recognition, where DNNs show superior results in comparison to other models.
Numerical Investigation of a Turbine Guide Vane Exposed to Rotating Detonation Exhaust Flow
Authors: Asli Majid , Cuciumita Cleopatra , Stathopoulos Panagiotis , Paschereit Christian Oliver 
Published: November 2019

Abstract
Detonative Pressure Gain Combustion has the potential to increase the propulsion efficiency of aero-engines and the thermal efficiency of stationary gas turbines. Important advances were made in this field, especially in the case of Rotating Detonation Combustion (RDC). Although experimental and numerical studies reported in the literature have significantly increased in number, the major open problem is a lack of efficient turbomachinery to transform the fluctuating potential energy from an RDC into power output. For this problem to be properly addressed, time resolved data at the outlet of an RDC needs to be collected. As a first step, numerical data can be used to generate a geometry for the turbine, which must be validated experimentally. To determine the performance of a turbine vane row, total pressure losses need to be measured. There are several challenges in measuring the total pressure between the outlet of an RDC and the inlet of a turbine vane row. The high temperature values, the distance of the pressure transducer from the outlet of the combustor lead to a lower time resolution of the pressure signal. The confined space is also an issue, allowing for very few options in measuring the total pressure. Another major problem is the shock wave that may form as a detached shock wave with respect to the body of the pressure probe at certain moments in the flow cycle, which leads to measuring a different value rather than the actual value of the flow field. To address these issues, the current study presents a numerical investigation of a guide vane row that was experimentally tested at the outlet of an RDC working on hydrogen and air under stoichiometric conditions. One of the vane rows was 3D printed with a geometry allowing the measurement of total pressure. Static pressure at the outlet of the RDC was also measured. It was observed that the measured pressures are average values in time. Based on these averages, the total inlet pressure and velocity variations in time were reconstructed in an exponential trend, according to the ones reported in the literature and the aforementioned experiments. These variations were set as inlet conditions for transient numerical simulations. Results show that the total pressure amplitude decreases significantly when the flow passes the annulus and the vanes as well. By looking in to the flow field detail, the presence of shock wave in front of the blade is investigated. Additionally, it is calculated that the average total pressure decreases 7.9% by the vane row.
High Speed Single Cavity Rig With Axial Throughflow of Cooling Air: Rig Structure and Periphery
Authors: Diemel Eric , Odenbach Stefan , Uffrecht Wieland , Villazon Jose Rey , Valencia Antonio Guijarro , Reinecke Mike 
Published: November 2019

Abstract
Appropriate understanding of heat transfer and temperature distribution of gas-turbine compressor disks is very important for mechanical rotor design. Accurate prediction of disk metal temperatures is key to ensure safe operation and furthermore rotor tip clearances has a significant influence on the compressor efficiency. Despite great improvements in the prediction of fluid motion and heat transfer in complex systems, the increasingly demanding requirement for more efficient compressors demands more accurate understanding of the flow around those disks. Therefore, a research rig has been designed and built which has thermal and aerodynamic analogy to high pressure compressor rotor cavities in gas-turbine engines aiming at gathering data at engine representative conditions. The rig consists of two disks, a cylindrical shroud and a stationary inner shaft. To simulate those conditions a heating and chilling module has been designed to enable the emulation of disk thermal gradients. For changing the operating point a flow delivery system with ten valves and two air heaters will be used. By measuring the radial pressure distribution inside the cavity it is possible to calculate the tangential velocity of the fluid core. In addition to that the disc and fluid temperature inside the cavity will be measured by a telemetry system, as well as the inlet and outlet condition of the fluid entering and leaving the cavity.
Towards Scale Resolving Computations of Condensing Wet Steam Flows
Authors: Post Pascal , Sembritzky Marwick , di Mare Francesca 
Published: November 2019

Abstract
In this paper we present a turbomachinery density-based CFD solver optimized for CPUs as well as GPUs, which accounts for complex thermodynamics including non-equilibrium condensation and two-phase flow, making extensive use of tabulation techniques. The two-phase flow is treated by means of the mono-dispersed Source-Term Euler-Euler model. The non-equilibrium wet-steam model is validated in classical nozzle test cases and its application in turbomachinery configuration is demonstrated in a well-documented steam turbine cascade in the context of classic RANS modeling. Finally, the LES-solver performance and scalability, together with its accuracy, are assessed and discussed on the basis of the well-known and theoretically relevant experiment by Comte-Bellot and Corrsin. For both, standard RANS computations, where an upwind schemes has been adopted, as well as for the LES computations, where a central scheme in skew-symmetric form has been employed, the solver shows remarkable computational speed and accuracy for non-ideal gas applications, rendering it suitable for more complex LES computations in steam turbine flows.
Structural Analysis of an Auxetic Casing Structure Incorporating Tip Blowing Casing Treatment Modification
Authors: Schmidt Tobias , Lorenz Jan , Gümmer Volker , Hupfer Andreas 
Published: November 2019

Abstract
In axial compressor design for aero engines high system efficiency and operational stability are two main objectives. Both depend on clearance-induced losses. Previous investigations at the Institute have resulted in a passive clearance controlled compressor design using additively manufactured auxetic casing structures. The extension to an active clearance controlled device to keep an approximately constant tip gap ratio during the entire flight mission is currently investigated. Constructive on these deliverables, the implementation of tip blowing casing treatment modification in a double-walled compressor casing including an auxetic inner structure is covered in this work and studied for maximum load conditions by means of Finite Element Analysis. The idea to supplement the current auxetic casing construction with casing treatment modification emerges from the aspiration to generate further stability improvements in the high-pressure domain and the exploitation of the design freedom provided by additive manufacturing. Key issues addressed in this work by conducting parameter studies are casing treatment positioning and corresponding structural correlations depending on circumferential quantity. The evaluation section concentrates mainly on the calculated stress level associated with tip blowing casing treatments because this value is crucial for prospective fatigue predictions. In order to compare the results, the auxetic casing structure without casing treatment modification serves as reference. Promising solutions for local stress reductions are also proposed and discussed.
From a structural mechanics perspective, the casing treatment modification generates very high and comparable notch stress levels at each position. Placing the casing treatments at the framework of the auxetic cells and splitting the inner casing ring results in tolerable stress levels.
Reducing Secondary Flow Losses in Low-Pressure Turbines With Blade Fences: Part II — Experimental Validation on Linear Cascades
Authors: Giovannini Matteo , Rubechini Filippo , Amato Giorgio , Arnone Andrea , Simoni Daniele , Yepmo Vianney , Satta Francesca , Bertini Francesco 
Published: November 2019

Abstract
This paper deals with the design of passive control devices for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. A novel kind of device is introduced which consists of shelf-like fences to be added to the blade surface. Such a device is intended to contrast the development of secondary flows, thus reducing losses and flow turning deviation with respect to the straight blade.
In this second part, an experimental campaign on a linear cascade is presented which is aimed at proving the beneficial impact of the blade fences. Experiments were carried out on a low-speed test-rig, equipped with a large scale blade representative of the stators of the engine-like environment considered in part I. Measurements are mainly focused on the stator losses and on the flow field at the stator exit. The performance of the blade fences was evaluated by comparing the straight cascade and the fenced ones. The measurements highlighted the impact of the blade fences on the development of the secondary flows, affecting both the stator losses and the non-uniformity of the flow field over the exit plane, which, in the actual stage environment, impacts the operation of the downstream blade row. Moreover, the comparison between CFD and experiments proved the accuracy of the CFD setup, thus suggesting its reliability in predicting the stage performance in the engine-like configuration.
Favre-Averaged Fourier-Based Methods for Gas Turbine Flows
Authors: Wang Feng , di Mare Luca , Adami Paolo 
Published: November 2019

Abstract
Steady Reynolds-Averaged Navier-Stokes (RANS) simulations are the workhorse of turbomachinery design. Recent trends in gas turbine design require full consideration of flow unsteadiness at the design stage to address issues of performance as well as integrity. Unsteady calculations using non-linear time marching methods are too computationally expensive to be used at the design stage. An alternative way is needed to reduce computational cost whilst retaining control on the accuracy of the simulations. To address this need, this paper presents a framework of Fourier-based methods for turbomachinery flows. The method is based on the non-linear harmonic (NLH) method. The method uses the favourable properties of Favre-averaging to obtain a simpler and more flexible formulation of the time-averaged system for NLH. This is ideal for implementing NLH in a CFD code where minimum modifications are desired. The approach allows the fidelity of the simulations to be tuned by switching on or off the coupling between the flow perturbations and the mean flow or the cross-coupling among the harmonics. This leads to a range of modelling fidelity for unsteady flows. For example, if the unsteady flow is linear, a linear harmonic method is sufficient for the design instead of using a harmonic balance simulation which has extra computational cost and slower convergence. The method has been tested on compressors and turbines which covers gas turbine flows in a range of flow regimes. Good agreement with data from non-linear time marching simulations are observed for all cases.