Volume 2E: Turbomachinery最新文献

{"title":"Effect of the Foam Metal Casing Treatment on a Low-Speed Axial Compressor","authors":"Jia Li, Dakun Sun, Reize Xu, Xu Dong, Xiaofeng Sun","doi":"10.1115/GT2020-15149","DOIUrl":"https://doi.org/10.1115/GT2020-15149","url":null,"abstract":"\u0000 Foam metal is a foam-like substance made out of metal and can be used in flow control, vibration damping and acoustic absorption mainly based on their special physical properties. A kind of foam metal casing treatment is proposed and tested in this study. The impact of the foam metal casing treatment on compressor stability and noise reduction are experimentally investigated. The foam metal selected in the experiments is constructed from ferronickel and its PPI (pores per inch) is 35. The foam metal casing treatment comprises annular support casing and foam metal ring. The effect of foam metal location on stability of the test compressor are investigated by placing shims in support casing. Both time-mean and high-response instrumentation are applied to capture the steady and unsteady compressor performances with the presence of the foam metal casing treatment. 20 microphones of G.R.A.S type are used to measure in-duct acoustic level of the compressor. It is found that the SMI (stall margin improvement) is 36.1% and the efficiency loss is 1.5% at location 7. When foam metal moves to rotor leading edge, the SMI as well as the efficiency loss are getting smaller. The optimal location in the experiments is location 4 where the SMI of compressor is 14.9% and the efficiency loss is 0.1%. The interaction of foam metal with flow in the blade tip region at these locations are investigated and presented in detail. The PSD (power spectrum density) analysis is carried out to show the unsteady signal development in stall inception. The noise attenuation varies in 0.18∼1.6 dB when foam metal is at different locations. Finally, the mechanism and application of the foam metal casing treatment are also discussed.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"523 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114820923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclostationary Approach for Instabilities Detection and Condition Monitoring of Centrifugal Compressor","authors":"M. Stajuda, D. Cava, G. Liśkiewicz","doi":"10.1115/GT2020-15699","DOIUrl":"https://doi.org/10.1115/GT2020-15699","url":null,"abstract":"\u0000 This study intends to explore the capabilities of the cyclostationary approach for instabilities detection and operating conditions monitoring of centrifugal compressors.\u0000 Cyclostationary approach offers powerful signal analysis methods, applicable to different processes. It was proven useful for analysis of vibration, acoustic and pressure data for systems exhibiting periodicity. Cyclostationarity has been used for extracting subtle changes between cycles of the periodic signal which could be used for condition monitoring. Recent research focuses on employing this method for fault indication. Cyclostationary approach has not been extensively used in the field of turbomachinery, except for a few cases when it was proven to give a better insight into flow structure than standard signal processing techniques and allow for the detection of instabilities in flow systems. Thus, the cyclostationary approach may be suitable for instabilities detection and condition monitoring in centrifugal compressors.\u0000 This paper exploits various techniques employing a cyclostationary framework for instabilities detection and operating conditions monitoring with the use of pressure signals from the low-speed centrifugal compressor. The most prospective cyclostationarity-based indicators are applied for the detection of instabilities. Due to a lack of second-order cyclostationarity, the study confines to the analysis of first-order cyclostationarity strongly exhibited in the compressor pressure signal. First-order cyclostationarity analysis provides an indication of instabilities and working conditions differentiation, but due to time-domain sampling, it is not fully robust and reliable. The highest potential is perceived in the cyclostationary approach use to extract changes between cycles. Different measures of change in variability could serve as a valuable indicator of instabilities.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114463083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Prediction of Rotating Stall in an Industrial Gas Turbine Compressor","authors":"S. Krishnababu","doi":"10.1115/GT2020-15330","DOIUrl":"https://doi.org/10.1115/GT2020-15330","url":null,"abstract":"\u0000 An investigation is presented into the computation of rotating stall in an industrial gas turbine compressor using a hybrid whole annulus and single passage computational domain. The objective of this investigation is to demonstrate the use of large-scale unsteady computations with quicker turn-around times in the design cycle to develop and evaluate several variable guide vane schedules and/or bleed settings. This means that subsequent engine test campaign could be carried out with significantly lower test matrix size in terms of the number of variable guide vane schedules and/or the handling bleed settings thus reducing the overall development time and cost. Rotating stall that was measured and characterised during a previous compressor rig test (Krishnababu, et al. [1]) were successfully predicted by large-scale unsteady computations using TurboStream. The predicted number of stall cells and their speed agreed closely with the test data. The methodology validated was applied to predict and mitigate the rotating stall in the development of a compressor for a new gas turbine engine. Using this approach, it was possible to define bleed control system that ensured stall free operation.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129326316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the Condition Number of the Inverse Fourier Transform Matrix on the Solution Behavior of the Time Spectral Equation System","authors":"Sen Zhang, Dingxi Wang, Yi Li, Hangkong Wu, Xiuquan Huang","doi":"10.1115/GT2020-14754","DOIUrl":"https://doi.org/10.1115/GT2020-14754","url":null,"abstract":"\u0000 The time spectral method is a very popular reduced order frequency method for analyzing unsteady flow due to its advantage of being easily extended from an existing steady flow solver. Condition number of the inverse Fourier transform matrix used in the method can affect the solution convergence and stability of the time spectral equation system. This paper aims at evaluating the effect of the condition number of the inverse Fourier transform matrix on the solution stability and convergence of the time spectral method from two aspects. The first aspect is to assess the impact of condition number using a matrix stability analysis based upon the time spectral form of the scalar advection equation. The relationship between the maximum allowable Courant number and the condition number will be derived. Different time instant groups which lead to the same condition number are also considered. Three numerical discretization schemes are provided for the stability analysis. The second aspect is to assess the impact of condition number for real life applications. Two case studies will be provided: one is a flutter case, NASA rotor 67, and the other is a blade row interaction case, NASA stage 35. A series of numerical analyses will be performed for each case using different time instant groups corresponding to different condition numbers. The conclusion drawn from the two real life case studies will corroborate the relationship derived from the matrix stability analysis.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121471268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic Mode Decomposition Analysis of Separated Boundary Layers Under Variable Reynolds Number and Free-Stream Turbulence","authors":"M. Dellacasagrande, J. Verdoya, D. Barsi, D. Lengani, D. Simoni","doi":"10.1115/GT2020-16322","DOIUrl":"https://doi.org/10.1115/GT2020-16322","url":null,"abstract":"\u0000 A flat plate boundary layer has been surveyed by means of time-resolved particle image velocimetry (PIV) under variable Reynolds number (70000 < Re < 150000) and turbulence intensity level (1.5% < Tu < 2.5%). The PIV visualizations were completed in two measuring planes, that are oriented both normal and parallel to the wall. For the wall-parallel configuration, the measuring plane is located inside the boundary layer. The PIV data were post-processed by applying Dynamic Mode Decomposition (DMD), which provides frequency based modes and their corresponding growth rate. The effects of Re and Tu variation on the amplification of the dominant wavelength within the separated shear layer, which is responsible for transition, is the main subject of the present work.\u0000 The DMD modes and related eigenvalues were computed with reference to the main streamwise coordinate. This allowed discussing the effects due to the main flow parameters on the amplification of the dominant streamwise wavelengths within the separated shear layer (Kelvin-Helmholtz modes). The growth of such streamwise modes ends with the formation of large scale vortices, whose breakup forces transition. In order to obtain the effective distribution of the maximum growth rate of fluctuations at different locations and times, the DMD domain was continuously extended in the streamwise direction, accounting for a specified number of periods characterizing the large scale K-H vortices.\u0000 In order to reduce the time-space dependent results obtained by the DMD procedure, a probability density function of the most unstable wavelength and the corresponding growth rate has been computed. For the present data set, the spatial growth rate of fluctuations is found to increase at the higher Reynolds number, while it slightly reduces with increasing the Tu level. The procedure and findings discussed in this work shall be suitable for designing active control systems, such as harmonic blowing for separation control.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130241887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unsteady Flow Simulation Through Stator-Rotor Blade Rows in Intermediate-Pressure Steam Turbines With Cutback Blades","authors":"Hironori Miyazawa, A. Uemura, Takashi Furusawa, S. Yamamoto, K. Yonezawa, S. Umezawa, Shuichi Ohmori, Takeshi Suzuki","doi":"10.1115/GT2020-14937","DOIUrl":"https://doi.org/10.1115/GT2020-14937","url":null,"abstract":"\u0000 Stator and rotor blades in intermediate-pressure steam turbines gradually deteriorate during operation because of solid particle erosion. In addition to that, turbine blades unexpectedly crack because of metal fatigue or thermal stress deformation. As eroded blades increase the aerodynamic losses and cracked blades may induce rupture of the blade, the periodic maintenance, repair, and overhaul of steam turbines is essential. Eroded or cracked blades should be replaced with new ones or repaired for further use. Cutback treatment is one of the repair methods wherein the deteriorated trailing edge on a turbine blade is removed to avoid further cracking and blade fracturing. The use of cutback blades can reduce the replacement cost; however, that may affect the steam flow and the turbine’s performance. In this study, we numerically investigated the effect of the blade deterioration on the performance of a three-stage intermediate-pressure steam turbine using a numerical method that was developed at Tohoku University. Further various cutback lengths were considered for the deteriorated first-stage stator-blade trailing edge. The obtained numerical results indicate that the cutback first-stage stator blades certainly affected the steam flow in the turbine, resulting in a negative influence on the torque obtained from the adjacent rotor blades, which depends on the cutback length. However, the torque decrement can be mitigated by arranging the cutback and non-cutback stator blades alternately in a row.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"29 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126612977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study on Internal Flow Field of a High-Speed Centrifugal Compressor at Different Altitudes","authors":"Xinghang Yu, Hongwei Ma, Lei Shi, Lianpeng Zhao","doi":"10.1115/GT2020-15118","DOIUrl":"https://doi.org/10.1115/GT2020-15118","url":null,"abstract":"\u0000 The alteration of altitude will affect the stability of centrifugal compressors. In this paper, the pressure field on the casing wall of a high-speed centrifugal compressor at two different altitudes (h = 0m and h = 4500m) was investigated by using 15 high-response pressure sensors. The operating condition of the centrifugal compressor ranged from choke condition to developed stall condition. The results show that the interaction of the shock wave and splitter-blade tip leakage flow occurs at 70% chord region near the choke condition, and the loss is more severe at the high altitudes. At the near-stall condition, the unstable disturbance at the low altitude is caused by the collapse of the horseshoe vortex, and the unstable disturbance at the high altitude is dominated by advanced breakdown of the main-blade tip leakage vortex. At the developed-stall condition, the stall mechanisms at the two altitudes are different, both of which are closely related to the main-blade tip leakage flow. With the decrease of flow rate, the unsteady disturbance caused by the volute tongue moves upstream from the diffuser to the impeller inlet. At the same time, the unsteady disturbance propagates along the opposite direction of the rotational direction in the partial impeller passage at the low altitude case. However, the circumferential propagation characteristics at the high altitudes case are not obvious.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131061639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of a Mixed-Flow Transonic Compressor for Active High-Lift System Using a 3D Inverse Design Methodology","authors":"Peng Wang, M. Vera-Morales, Patrick La, M. Zangeneh, N. Maroldt, Ole Willers, Felix Kauth, J. Seume","doi":"10.1115/GT2020-15645","DOIUrl":"https://doi.org/10.1115/GT2020-15645","url":null,"abstract":"\u0000 This paper presents the redesign of an electrically driven mixed flow transonic compressor by using a 3D inverse design methodology. The compressor will be used for an active high-lift system application that aims to delay the onset of stall and thus contributing to the reduction of both the aircraft noise footprint and the impact of aviation emission on local air quality.\u0000 As part of a collaborative work between the Institute of Turbomachinery and Fluid Dynamics of the Leibniz University Hannover and Advanced Design Technology Ltd., an existing optimized compressor stage for this application is redesigned using a 3D inverse method. The new compressor design presents an increase in pressure ratio and total-to-total isentropic efficiency of more than 5.5% and 1% respectively at design point. The higher PR at design point allows the compressor to be run at lower rotational speeds, which decreases the load on the electric motor and the power electronic systems, and hence contributing further to the overall weight reduction of the entire system.\u0000 The advantage of using an inverse design methodology is shown in this paper as a method that allows a very simple parameterization, reducing significantly the design time and hence allowing the exploration of wider design spaces, with the potential of reaching more innovative and efficient designs. The fast and reliable design and analysis of components represents an important advantage for the enhancement of aircraft electrification, where long design times are often a barrier for the exploration of system configurations.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128999101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Investigation Into the Effect of Clearance Aspect Ratio on the Performance of a Variable Geometry Vaned Diffuser for Automotive Turbocharger Application","authors":"L. Gibson, S. Spence, S. Kim, C. Stuart, Martin Schwitzke, A. Starke, D. Filsinger","doi":"10.1115/GT2020-14905","DOIUrl":"https://doi.org/10.1115/GT2020-14905","url":null,"abstract":"\u0000 The current state-of-the-art in radial compressor design for automotive turbocharger applications utilize impellers with a high trailing edge backsweep angle and a vaneless diffuser to provide a high boost pressure over a wide operating range. A unique feature of this type of design is that the peak efficiency island is typically located near the choke side of the compressor map. As such, the compressor efficiency is generally satisfactory when the engine is operating at high speed, such as the rated power condition. However, at low speeds the engine operating line is located close to the compressor surge line where the efficiency is generally modest. Thus, there is a need to improve the compressor efficiency at low engine speeds without compromising performance near the choke side of the map or the overall map width.\u0000 Variable geometry devices have shown good potential to improve the compressor performance without a compromise in map width. In general, variability is achieved by moving walls or rotating vanes to best suit the flow conditions for a given mass flow rate. In order for this to be practically realised, a clearance or gap is required between the stationary and moving parts. This ultimately gives rise to leakage flows within the compressor stage and generally results in a lower achievable efficiency relative to the fixed geometry configuration.\u0000 A study by the authors on an on/off type variable geometry vaned diffuser identified significant loss mechanisms due to the clearances required for the vanes to slide in to and out of the main flow path. Moreover, the endwall position of the clearance was found to have a marked impact on the compressor stability and peak efficiency. This paper assesses the effect of the clearance depth to width ratio (or aspect ratio) at different endwall positions with the aim of identifying an appropriate geometry and position to approach an optimised design.\u0000 Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations were performed using ANSYS CFX at three operating speeds to obtain a broad sense of the effect of the clearance aspect ratio on the compressor performance. It was found that a high value of aspect ratio enabled the formation of large vortical structures in the vaned diffuser. The mixing between the core flow and the vortical structures resulted in significant losses in the vaned diffuser and affected the compressor map width differently depending on the endwall position.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"199 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133883558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and Numerical Study of an Open Impeller Centrifugal Compressor Stage Utilising 3D Diffuser End Wall Contouring for Operating Range Extension","authors":"D. Hermann, M. Wirsum, D. Robinson, P. Jenny","doi":"10.1115/GT2020-14782","DOIUrl":"https://doi.org/10.1115/GT2020-14782","url":null,"abstract":"\u0000 Highly efficient and concurrent flexible operation are heavy demands on today’s centrifugal compressor units. Diffuser end wall contouring is a measure to delay the incipience of instability and therefore to extend the compressor’s operating range while maintaining efficient performance. In the presented paper, a hubside wall contouring, applied in the vaneless space upstream the diffuser’s leading edge and within the diffuser passage of a state-of-the-art centrifugal compressor with an open impeller is examined. CFD computations are performed for both a baseline diffuser design with parallel channel walls and the hub-side wall contoured diffuser design. Comparisons of characteristic and diffuser stability decisive flow variables are made in perpendicular sections along an extrapolated camber line of the diffuser vane for full span, near shroud and near hub wall. In operating points near the stability limit at two different stage Mach numbers, the stabilizing effect of the hub-side wall contouring on the diffuser flow is clearly shown. In a scale-model test rig, experimental data including pneumatic 5-hole probe data for a full diffuser blade-to-blade passage, static wall pressures at various planes as well as total temperature was measured. The experimental data is utilized for validation of the presented numerical calculations. The flow stabilizing effect of the hub-wall contouring is clearly visible in the measurements, which showed 8% range extension at highest stage Mach number Mu2 = 1.16 and a range extension of 2% at design stage Mach number Mu2 = 1.0.","PeriodicalId":194198,"journal":{"name":"Volume 2E: Turbomachinery","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127420751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}