bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Mixture Quality in Multi-Injector Burner Systems, Part I: Experimental Setup
Authors: Marquez Macias Fabian , Hirsch Christoph , Sattelmayer Thomas , Huth Michael , Meisl Jürgen 
Published: October 2022

Abstract
A new approach to calculate the mixture statistics in multi-injector burner systems from a single injector data base is presented in the paper. In such systems, the mixture quality is highly sensitive to the flow rate and the skewness of the inflow velocity profile. To determine the mixture fraction statistics from these two parameters for a particular injector in a multi-injector configuration, O-POD is suggested using results from RANS-CFD as the observable. The O-POD mixing database is determined experimentally from two setups: First the mixture quality in a single injector at ideal inflow conditions is studied. Then the same injector type is investigated in a generic multi-injector burner system (MIB). To characterise the mixture quality, the mixing probability mass function (PMF) at the injector exit is measured by means of LIF and high speed imaging. The data obtained for both the single injector under ideal inflow and the MIB are presented. These studies of the mixture behaviour reveal that an asymmetric inflow velocity profile leads to a significant increase of unmixedness, which is seen as a negative skewness of the mixing PMFs. This effect becomes stronger at higher momentum flux density ratios due to the higher penetration depth of the fuel jets. The application of the O-POD to the database shows that the PMF can be accurately modeled with only 3 modes.
An Euler-Based Throughflow Approach for Centrifugal Compressors – Part A: Extension and Modifications of Models
Authors: Jenzen Rebecca , Woiczinski Christian , Schuster Sebastian , Brillert Dieter 
Published: October 2022

Abstract
This paper presents the extension and validation of an Euler-based throughflow solver for the analysis of centrifugal compressors. The conservation equations are augmented with aerodynamic models suitable for describing a centrifugal compressor. The paper analyzes the impact of the varying meridional pitch angle on the blade force model and proposes two different approaches to consider this variation in the calculation. Further, the paper includes the development and implementation of additional loss models based on enthalpy loss coefficients, which take into account the different loss mechanisms in centrifugal compressors. In this contribution, the modifications are introduced and discussed. To validate the modifications, they are implemented in an existing Euler-based throughflow solver called tFlow. First, the extended solver is compared with the results of computational fluid dynamics (CFD) and calibrated with respect to the total efficiency at the design point. The resulting performance values predicted by the extended solver at off-design conditions are in good agreement with the CFD results. Subsequently, in Part B of the paper, experimental data is used to validate the predicted performance values of the extended solver. The experiments are carried out on a centrifugal compressor test rig described and explained in detail in Part B of this paper. The performance values predicted by the extended solver are in good agreement with the experimental data with respect to the pressure ratio.
Blisk With Small Geometry Mistuning and Blend Repair: As-Measured FE Model and Experimental Verification
Authors: Zhou Biao , Zhao Jingchao , Ye Nan , Berruti Teresa M. 
Published: October 2022

Abstract
This paper presents an ‘As-Measured Model’ of a blended blisk, built upon the measurement of the true geometry of the blisk by the 3D optical scanning technology. This high-fidelity model aims to account for the variances of blade frequencies and mode shapes within the real blisk in the presence of both the blend repair and inherent geometry mistuning due to manufacturing, etc. An improved mesh updating strategy is proposed to adapt a seed blisk finite element model to the measured geometry. The resultant ‘as-measured model’ is therefore able to accurately represent the measured blade-to-blade geometry variances. The classical blade detuning test in combination with a novel ‘correction’ procedure is employed to experimentally evaluate the ‘blade-alone’ frequency mistuning pattern in the real blisk. Experimental verification of the ‘as-measured model’ demonstrates that it is able to not only capture the ‘blade-alone’ frequency and mode shape variations due to both the blend and intrinsic blade geometry variances, but also to reproduce the global dynamics of the blended blisk with acceptable accuracy.
Effects of Sideslip Direction on a Rear Fuselage Boundary Layer Ingesting Fan
Authors: Castillo Pardo Alejandro , Hall Cesare A. 
Published: October 2022

Abstract
Boundary layer ingestion (BLI) offers potential reductions in fuel burn and emissions. The propulsive fuselage concept features an aft fan that ingests the 360° fuselage boundary layer. A critical condition for this configuration occurs when a sideslip angle arises between the aircraft longitudinal axis and the free-stream velocity. The sideslip flow in combination with the air-frame generates inlet distortion that depends on the sideslip direction. In particular, the sideslip increases flow into the windward side of the intake and reduces the flow on the opposite side, leading to either co-swirl or counter-swirl at the fan face.
This paper investigates the effect of sideslip direction on the aerodynamics of an aft BLI fan. Experimental measurements have been taken in a low-speed fan rig with representative total pressure and swirl distortion. These tests have been complemented by full-annulus URANS simulations to understand the impact of sideslip on the rotor and OGV flow fields.
The results show that positive sideslip (sideslip that produces counter-swirl) increases the fan work and incidence, but the additional losses are relatively small. However, negative sideslip results in lower loading, negative incidence and greater losses. The stage loading was 28% higher and the stage efficiency was 1.65% higher for positive versus negative sideslip. The positive sideslip case was also found to lose some operating range, equivalent to 2% of nozzle area. Overall, the fan design tolerates the sideslip distortion well and demonstrates the importance of the coupling of both swirl and total pressure distortion with the fan aerodynamics.
Experimental Investigation of Effusion Film Cooling on a Cylindrical Leading Edge Model
Authors: Huang I-Cheng , Lin Kuan-Hsueh , Huang Chih-Yung , Liu Yao-Hsien 
Published: October 2022

Abstract
Effusion film cooling is effective for cooling high temperature turbine blades because it requires less coolant and produces a more uniform temperature distribution than conventional film cooling. Effusion cooling for a cylindrical model representing the leading edge of a gas turbine blade was investigated. The experiment was performed in a low-speed wind tunnel at a Reynolds number of 100,000. Pressure sensitive paint was used to measure the adiabatic film cooling effectiveness. Additive manufacturing was used to fabricate a porous structure on the test cylinder for effusion cooling. Both simple and compound angles were used for cooling injection. The effects of streamwise and spanwise hole spacings, turbulence intensities (1%, 8.7%), and blowing ratios (0.075, 0.15, 0.3, and 0.6) were studied. The effusion hole diameter was 0.1 cm, and the spanwise hole pitch-to-diameter ratios were either 2 or 4. Compared with conventional film cooing, effusion cooling achieved higher cooling effectiveness and produced better coolant coverage. Increasing the streamwise spacing noticeably reduced the cooling effectiveness for the simple-angle design due to film liftoff; the compound-angle designs thus achieved higher effectiveness. The simple-angle holes were more sensitive to changes in the mainstream turbulence intensity; increases in the turbulence intensity promoted the mixing of the coolant with the mainstream. Moreover, effusion cooling was more resistant to coolant lift-off at high blowing ratios.
Experimental Investigation Into Oil Shedding From a Rotating Cup Geometry
Authors: Cageao Paloma Paleo , Johnson Kathy , Ambrose Stephen , Omar Rajab 
Published: October 2022

Abstract
Oil shedding from rotating components and static elements within rotating systems has a number of applications within the design and understanding of transmission systems as well as wider industrial applications. There is a reasonable body of prior research on liquid ejection from rotating cups and discs where the cup/disc element is on the end of the rotative. This study reports results from an experimental investigation where a cup element was mounted onto a relatively large diameter shaft with the shaft extending through the cup. The primary aim of the study was to investigate and characterise the shedding behaviour over a range of shaft speeds and oil supply rates.
High speed images were acquired of shedding from the cup at 90° and 270° from top dead centre (clockwise rotation). Three disintegration modes are observed: droplet, ligament and sheet with transition dependent on operating condition. Transition boundaries on non-dimensional regime maps are compared to published literature showing a good match to data for a spinning disc.
In some industrial configurations of interest oil sheds from a rotating component/element onto a static surface prior to subsequent ejection into a chamber or housing. In such cases the tangential component of velocity of the shedding oil is significantly reduced. This current work explores the effect on oil disintegration and shedding when a static element is introduced into the system. The flow behaviour of the air-oil interface at the edge of the static and on the front face of the static element was recorded as part of the investigation and showed a range of flow patterns including stratified smooth film, stratified wavy film with some droplet shedding and turbulent film with significant droplet shedding.
Application of Intentional Mistuning to Reduce the Vibration Susceptibility of a Steam Turbine Wheel
Authors: Beirow Bernd , Golze Mark , Popig Frederik 
Published: October 2022

Abstract
Intentional mistuning is employed for a last stage turbine wheel featuring 51 blades to alleviate both the flutter susceptibility and maximum forced response. Primarily, operations at nominal speed under part-load conditions may cause unfavorable flow conditions facilitating flow separation. As a consequence, the original design intention with identical blades features negative aerodynamic damping ratios with respect to the first bending mode family. In order to prevent any self-excited vibration phenomena, intentional alternate mistuning is utilized to increase the least aerodynamic damping ratio as far as it takes a positive value and hence, to contribute to a stabilization of the rotor. For the purpose of numerically analyzing the vibration behavior, reduced order models are built up, which are based on modal reduction techniques, namely the subset of nominal system modes and the fundamental mistuning model. These types of models conveniently allow for considering both different mistuning distributions in terms of probabilistic analyses and the aeroelastic interaction by means of prescribing aerodynamic damping ratios and aeroelastic natural frequencies of the tuned counterpart or aerodynamic influence coefficients, respectively. A detailed study is presented regarding the correction of frequency mistuning magnitudes in terms of considering the impact of centrifugal stiffening, which plays a significant role in case of long low pressure turbine blades featuring high aspect ratios.
Since alternate intentional mistuning cannot be implemented perfectly, every bladed wheel as manufactured will exhibit small but unavoidable structural deviations from the design intention, which are known as random mistuning. To ensure the robustness of the intentional mistuning solution in terms of positive aerodynamic damping ratios at any time, comprehensive probabilistic analyses are conducted with respect to superimposing random structural mistuning at first. Secondly, the impact of varying mistuning magnitude is analyzed. Thirdly, the robustness towards aerodynamic mistuning is investigated by means of small variations of aeroelastic influence coefficients and consequently, the inter blade phase angle dependent aerodynamic damping curves. Moreover, it becomes apparent that alternate intentional mistuning superimposed with both, random structural and aerodynamic mistuning also mitigates the maximum forced response at part-speed conditions.
CFD Flow Field Assessment and Performance Map Generation of A Turbocharger Radial Turbine Attempted to Be Matched With a Downsized Diesel Engine
Authors: El Hameur Mohamed Amine , Cerdoun Mahfoudh , Tarabet Lyes , Ferrara Giovanni 
Published: October 2022

Abstract
The present paper aims to propose an efficient methodology to match aerodynamically a 1.5 l, three cylinders downsized Diesel engine, with a selected turbocharger to boost its performance based on 1D codes and CFD simulation. In this aspect, a radial turbine’s stage was sized and designed applying 1D preliminary design in-house codes. Then, a CFD simulation was established to investigate the flow field through its components and to predict its performance. Based on the simulation data, a turbine’s map was generated via gas-dynamic simulation software. On the other hand, a turbocharger compressor was selected from a database. Therefore, the performance maps of the designed turbine and the selected compressor were matched with the engine simulation model. From the findings, the new turbocharged engine developed an operating area far from the compressor limits at the entire engine speed range, with a surge margin of 23.37% at the engine rated power. The engine thermal efficiency, brake specific fuel consumption, compressor and turbine isentropic efficiencies measured on the new turbocharged engine expressed an enhancement at the engine rated speed of about 6.79%, 6.36%, 19.91% and 3.86%, respectively, compared with the original engine. Furthermore, maximum deviations of 7.43% and 0.47% were measured between the new and the original turbocharged engines in terms of in-cylinder pressure and temperature, respectively, which guarantee the engine’s thermodynamic strength. Finally, the developed methodology reported satisfactory results in terms of the engine’s secure functioning and predicted performances, which can be considered as an important basis before initiating any detailed conception.
Comparing Gradient-Free and Gradient-Based Multi-Objective Optimization Methodologies on the VKI-LS89 Turbine Vane Test Case
Authors: Hottois Romain , Châtel Arnaud , Coussement Grégory , Verstraete Tom , De Bruyn Tom 
Published: October 2022

Abstract
The present paper addresses the multi-objective aerodynamic shape optimization of the two-dimensional LS-89 turbine cascade. The objective is to minimize the entropy generation at subsonic and transonic flow conditions while maintaining the same flow turning. Nineteen design variables are used to parametrize the geometry. The optimization problem is used to compare two major classes of optimization algorithms and at the same time deduce if this problem has multiple local solutions or one global optimum. A first optimization strategy uses a gradient-based Sequential Quadratic Programming algorithm. This SQP algorithm allows to directly handle the non-linear constraints during the optimization process. An adjoint solver is used for computing the sensitivities of the flow quantities with respect to the design variables, such that the additional gradient computational cost is nearly independent of the number of design variables. In addition, the same optimization problem is performed with a gradient-free - metamodel assisted - evolutionary algorithm. A comparison of the two Pareto-fronts obtained with both methods shows that the gradient-based approach allows to find the same optimum at a reduced computational cost. Moreover, the results suggest that the considered optimization problem is uni-modal. In other terms, it is characterized by a single optimal solution.
New Method for Cycle Performance Prediction Based on Detailed Compressor and Gas Turbine Flow Calculations
Authors: Petrovic Milan V. , Wiedermann Alexander , Banjac Milan B. , Milic Srdjan , Petkovic Djordje , Madzar Teodora 
Published: October 2022

Abstract
Gas turbines have made significant progress in recent years. The efficiencies of the compressor and turbine were improved based on achievements in aerodynamics, i.e., on the introduction of numerical flow simulation. The introduction of massive cooling and thermal barrier coating permitted a considerable increase in the turbine inlet temperature. These developments led to a significant increase in the thermal efficiency of gas turbines. However, most of the existing tools for predicting cycle performance are based on 0D compressor and turbine maps for the efficiency and pressure ratio as a function of the mass flow. Such tools cannot simulate all new trends in gas turbines in the most efficient way. The new method proposed here is a 2D method based on detailed flow calculations in the compressor and the gas turbine. Previously developed through-flow tools for compressor/turbine flow simulation and performance prediction were applied for this purpose. The processes in the compressor and the turbine are connected by calculation of the processes in the combustion chamber and the secondary and cooling air system. The turbine inlet temperature is determined by an iterative procedure. The method allows the accurate prediction of performance at every operating point. Air cooling bleeds in the compressor and its injections in the turbine blades can be simulated precisely. Also, adjustments of the inlet guide and stator vanes and their influence on compressor behavior can be accurately taken into account at every operating point. Finally, calculation of the combustion and the flow in the compressor and the turbine allows a simulation with correct gas composition and humidity of the air. The method is demonstrated on a case of an industrial gas turbine. The numerical results were compared with experimental data and showed very good agreement. The procedure is rapid and robust and permits optimization of the different solutions during the design phase.
Investigation of the Transient Closing Behavior of a Radially Adaptive Seal
Authors: Lofts James , Schwitzke Corina , Bauer Hans-Jörg , Peltier Vincent , Zhou Kunyuan 
Published: October 2022

Abstract
New radial adaptive sealing concepts in the secondary air system have the potential to increase the partial load efficiency of turbomachinery and accelerate load ramps. These seals are pressure activated, adjusting to engine conditions in order to maintain a minimum gap width during the entire load cycle, defined as the seal’s operating gap width. In this context a hydrostatic advanced low-leakage (HALO) seal was experimentally investigated in the adaptive seals test rig at the Institute for Thermal Turbomachinery (ITS), with a focus on the transient behavior of the seal closing to its’ operating gap width. For this measurement campaign, the pressure ratio, pressure difference, pressure ramp speed and swirl were varied over a series of closing-hold-opening pressure cycle test runs. All measurements were performed without rotation of the test rig rotor.
In this paper, the results of these experimental investigations are presented and analysed. From these results, the relative influence of the pressure difference and the pressure ratio across the seal on the transient seal behavior is compared. Of particular interest is the effect of changing the pressure ramp gradient on the operating gap width. Additionally, the results are compared against previous published HALO-seal investigations. The results presented in this study give detailed insight into the transient movement of a HALO seal under various engine-similar influencing parameters. This is crucial to understanding how the seal behavior and performance will be affected when operating under different conditions and in different applications.
A Predictive Method for Helicopters Engine Installation Losses Determination
Authors: Di-Marco Alexandre , Lecauchois Claire , Fayard Benoit , Sagaut Pierre 
Published: October 2022

Abstract
Helicopter performance is key element for the competitiveness of the aircraft and is usually define during flight test. Due to the increasingly complicated design of air intake, estimating the installation effect prior to flight test can be useful to minimize effort and cost. This paper proposed a methodology to predict helicopters engine installation effect that can be used prior to any flight test. For that purpose a two step methodology has been developed using first CFD simulation to determine the aerodynamic and aerothermal disturbances generated by the helicopter air intake and then a thermodynamic engine model to estimate the installation losses. These two steps were validated against in flight measurements and it has been shown that combining all individual effects in the model improve the quality of the installation losses prediction. The global accuracy in terms of installation losses absolute value and shape show that the proposed method provide sufficient accuracy in an industrial context.
Effect of Solidity and Aspect Ratio on the Aerodynamic Performance of Axial-Flow Fans With 0.2 Hub-to-Tip Ratio
Authors: Masi Massimo , Danieli Piero , Lazzaretto Andrea 
Published: October 2022

Abstract
Aspect ratio and solidity play complementary roles in the aerodynamic design of axial fan rotor blades. Few studies have experimented the effect of the aspect ratio of rotor blades on the performance of low-speed axial fans or on its interaction with blade solidity in terms of fan aerodynamic performance. This study examined the selection of the solidity and blade aspect ratio in the preliminary design of low-pressure industrial fans with minimized hub-to-tip ratios. The aim of this study was to make available to the fan community experimental data that allow determination of the optimal aspect ratio as a function of the blade solidity.
Various aspects of the performance of 16 prototypes of a 315-mm-diameter propeller fan were compared. The industrial fan prototypes all had a hub-to-tip ratio of 0.2 and were derived from four baseline designs conceived to ideally achieve the same best efficiency operation with different values of the aspect ratio. In addition, the prototypes’ assemblies were conceived to allow operation with different blade counts, i.e., with different rotor solidities at a fixed blade aspect ratio. The aerodynamic performance of the fans, measured in accordance with the ISO-5801 standard, was evaluated to assess the sensitivity and trends of the fan pressure and efficiency with respect to the blade aspect ratio and solidity. The measured effects of the aspect ratio and solidity are discussed on the basis of data available in the literature. The results of the experimental analysis were used to formulate general guidelines for the preliminary design of propeller fans with minimized hub-to-tip ratios.