Transient Performance Analysis of an Aero Gas Turbine Cooled Cooling Air Heat Exchanger

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Alberto Mucci ◽  
Foster Kwame Kholi ◽  
Man Yeong Ha ◽  
June Kee Min ◽  
Peeter Beecroft ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Numerical Models ◽  
Experimental Testing ◽  
Three Dimensional ◽  
Test Range ◽  
The Past ◽  
Secondary Air ◽  
Critical Components ◽  
Cooling Air ◽  
Facility System

Abstract Aviation faces several challenges to maintain growth while adapting to an environmentally viable footprint. Increasing efficiency, which in the past induced a steady rise in the turbine entry temperatures, requires successful cooling of critical components to relieve the combined effects of higher temperatures and pressures. Starting with a conceptual design that alters the flow path of the secondary air system to divert bled air into a heat exchanger, this research focuses on assessing the effects of actual flight conditions on a cooled cooling air (CCA) system. In particular, the study undertakes a transient analysis of the CCA heat exchanger under a stressful temperature increase. The performance of the unit from idle to max take off (MTO) conditions required a unique facility for experimental testing, also capable of reaching and sustaining the necessary specifications. The novelty of the concept compelled the development of numerical models to aid the design and evaluation of the experiment. These models use one- and three-dimensional techniques to perform preemptive analysis of the test range, to ensure safety during the actual test, and to provide valuable information about the facility system and the inner flow structure of the heat exchanger. The study completed successful experiments using numerically generated procedures. A back-to-back configuration, representative of multiple installations, offers evidence about the cross-influence of each heat exchanger. The research also examined the dynamic effects to provide the bases for further studies focusing on this topic.

8. Glaciers of the past

2018 ◽  
pp. 146-152
Author(s):  
David J. A. Evans
Keyword(s):  
Numerical Models ◽  
Ice Core ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Aerial Imagery ◽  
The Past ◽  
Glacial Landforms

To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.

Turbine Stator Well CFD Studies: Effects of Cavity Cooling Air Flow

2008 ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Stefano Zecchi
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Numerical Models ◽  
Engine Performance ◽  
Research Programme ◽  
Experimental Tests ◽  
Air Cooling ◽  
Manufacturing Companies ◽  
Secondary Air ◽  
Cooling Air

The improvement of the aerodynamic efficiency of gas turbine components is becoming more and more difficult to achieve. Nevertheless there are still some devices that could be improved to enhance engine performance. Further investigations on the internal air cooling systems, for instance, may lead to a reduction of cavities cooling air with a direct beneficial effect on engine performance. At the same time, further investigations on heat transfer mechanisms within turbine cavities may help to optimize cooling air flows saving engine life duration. This paper presents some CFD preliminary studies conducted on an two-stage axial turbine rig developed in a research programme on internal air systems funded by EU, named the Main Annulus Gas Path Interactions (MAGPI). Each turbine stage consists of 39 vanes and 78 rotating blades and the modelled domain includes both the main gas path of the two turbine stages and the second stator well. Pre experimental tests CFD computations were planned in order to point out the reliability of numerical models in the description of the flow patterns in the main annulus and in the cavities. Several computational meshes were considered with steady and unsteady approaches in order to assess the sensitivity to computational approach regarding the evaluation of the interactions between main annulus and disk cavities flows. Results were obtained for several cavities cooling air mass-flow rates and data were further analyzed to investigate the influence of the sealing flow inside the main annulus. MAGPI project is a 4 years Specific-Targeted-Research-Project (2007–2011) and its consortium includes six universities and nine gas turbines manufacturing companies. The project is focused on the analysis of interactions between primary and secondary air systems achieving a novel approach as these systems have, up to now, only been considered separately. In particular one of the tasks of the project will focus on heat transfer phenomena and delivering experimental data which will be used to validate the advanced design tools used by industries (CFD codes and correlative formulations).

Transient Regime Simulation From Idle to Maximum Take-Off Flight Conditions of Cooled Cooling Air Heat Exchanger for an Aero Gas Turbine Heat Management

2019 ◽  
Author(s):  
Alberto Mucci ◽  
Foster Kwame Kholi ◽  
Man Yeong Ha ◽  
June Kee Min ◽  
Peter A. Beecroft ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Gas Turbines ◽  
Experimental Testing ◽  
Dynamic Performance ◽  
Test Facility ◽  
Operating Pressure ◽  
Heat Management ◽  
Experimental Conditions ◽  
Cooling Air ◽  
Real Scale

Abstract The quest for improving the thermal efficiency of gas turbines has raised the turbine entry temperatures (TET) and hence the operating pressure ratios (OPR). However, the combination of high TET and high cooling flow temperature makes the cooling of the hot sections more challenging. A cooled cooling air heat exchanger (CCAHX) can be used to cool the high-temperature compressor offtake, showing improved steady aerothermal performance in terms of pressure and temperature. Presented here is the experimental testing of the CCAHX and the process used to generate a highly representative transient simulation of its dynamic performance between idle and Maximum Take-Off (MTO) flight conditions. Said simulation is primarily used to predict the performance during further experiments. Due to the harsh experimental conditions, the simulation guarantees safe operations of the test facility while advising on the right procedures to use during real scale tests. Due to the complex internal structure of the heat exchanger, a one-dimensional computational fluid dynamics (CFD) commercial software was employed to validate the models using results from steady-state data for a single CCAHX unit. Derived procedures from the 1D analysis are used to guide the transient testing at real scale flight conditions, where the core and fan flows are thermally-linked to two CCAHXs in a back-to-back configuration. Results show that the approach considered here can correctly predict the performance of a complex heat exchanger system in transient, fast-changing operations, as calculations in real flight conditions showed good agreement with experimental results of a real scale test.

The Flow Structure in Rotating Hollow Shafts With Radial Inflow and Axial Throughflow

2001 ◽  
Author(s):  
D. Brillert ◽  
A. W. Reichert ◽  
H. Simon
Keyword(s):  
Gas Turbines ◽  
Three Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Flow Losses ◽  
Secondary Air ◽  
Calculation System ◽  
Basic Equations ◽  
Cooling Air ◽  
Hollow Shafts

Modern heavy-duty gas turbines operate with high turbine inlet temperatures and thus require complex secondary air systems to ensure that blades and vanes are supplied with the necessary amount of cooling air. Low-emission gas turbines with a high thermal efficiency require minimum amounts of cooling and sealing air which means that secondary air systems must be designed with extreme accuracy. In previous papers, the secondary air system of Siemens Vx4.3A gas turbines and the calculation method used for their design were introduced. This paper deals with the calculation of the flow in cooling air passages in rotating hollow shafts with axial throughflow. The paper starts with a derivation of basic equations and a brief review of the work on this topic described in the literature. Then on the basis of these basic equations a simple one–dimensional model is described to predict the three–dimensional flow (losses, flow deflection) in the rotating hollow shafts for different massflow rates. The calculation system is completed by matching the correlations of the simple one–dimensional model to the results of the numerical simulations.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

scholarly journals Midface Reconstruction: Planning and Outcome

2020 ◽  
Vol 53 (03) ◽  
pp. 324-334
Author(s):  
Gautam Biswas
Keyword(s):  
Digital Imaging ◽  
3D Structure ◽  
Three Dimensional ◽  
The Past ◽  
Complex Anatomy ◽  
Osseointegrated Implants ◽  
Low Profile ◽  
3D Printed ◽  
Midface Reconstruction ◽  
Reconstruction Planning

Abstract Reconstruction of the complex anatomy and aesthetics of the midface is often a challenge. A careful understanding of this three-dimensional (3D) structure is necessary. Anticipating the extent of excision and its planning following oncological resections is critical.In the past over two decades, with the advances in microsurgical procedures, contributions toward the reconstruction of this area have generated interest. Planning using digital imaging, 3D printed models, osseointegrated implants, and low-profile plates, has favorably impacted the outcome. However, there are still controversies in the management: to use single composite tissues versus multiple tissues; implants versus autografts; vascularized versus nonvascularized bone; prosthesis versus reconstruction.This article explores the present available options in maxillary reconstruction and outlines the approach in the management garnered from past publications and experiences.

scholarly journals Effect of buried depth on thermal performance of a vertical U-tube underground heat exchanger

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 327-330
Author(s):  
Li Yang ◽  
Bo Zhang ◽  
Jiří Jaromír Klemeš ◽  
Jie Liu ◽  
Meiyu Song ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Simplified Model ◽  
Two Dimensional ◽  
Construction Sites ◽  
Full Size ◽  
Unit Depth ◽  
Research Show

Abstract Many researchers numerically investigated U-tube underground heat exchanger using a two-dimensional simplified pipe. However, a simplified model results in large errors compared to the data from construction sites. This research is carried out using a three-dimensional full-size model. A model validation is conducted by comparing with experimental data in summer. This article investigates the effects of fluid velocity and buried depth on the heat exchange rate in a vertical U-tube underground heat exchanger based on fluid–structure coupled simulations. Compared with the results at a flow rate of 0.4 m/s, the results of this research show that the heat transfer per buried depth at 1.0 m/s increases by 123.34%. With the increase of the buried depth from 80 to 140 m, the heat transfer per unit depth decreases by 9.72%.

scholarly journals Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

scholarly journals The Study of Three-Dimensional Fingerprint Recognition in Cultural Heritage

2021 ◽  
Vol 14 (4) ◽  
pp. 1-20
Author(s):  
Dzemila Sero ◽  
Isabelle Garachon ◽  
Erma Hermens ◽  
Robert Van Liere ◽  
Kees Joost Batenburg
Keyword(s):  
Image Processing ◽  
Cultural Heritage ◽  
Three Dimensional ◽  
Fingerprint Recognition ◽  
Person Identification ◽  
Imaging Technologies ◽  
The Past ◽  
Reconstruction Methods ◽  
Cultural Systems ◽  
Digital Fingerprint

Fingerprints play a central role in any field where person identification is required. In forensics and biometrics, three-dimensional fingerprint-based imaging technologies, and corresponding recognition methods, have been vastly investigated. In cultural heritage, preliminary studies provide evidence that the three-dimensional impressions left on objects from the past (ancient fingerprints) are of paramount relevance to understand the socio-cultural systems of former societies, to possibly identify a single producer of multiple potteries, and to authenticate the artist of a sculpture. These findings suggest that the study of ancient fingerprints can be further investigated and open new avenues of research. However, the potential for capturing and analyzing ancient fingerprints is still largely unexplored in the context of cultural heritage research. In fact, most of the existing studies have focused on plane fingerprint representations and commercial software for image processing. Our aim is to outline the opportunities and challenges of digital fingerprint recognition in answering a range of questions in cultural heritage research. Therefore, we summarize the fingerprint-based imaging technologies, reconstruction methods, and analyses used in biometrics that could be beneficial to the study of ancient fingerprints in cultural heritage. In addition, we analyze the works conducted on ancient fingerprints from potteries and ceramic/fired clay sculptures. We conclude with a discussion on the open challenges and future works that could initiate novel strategies for ancient fingerprint acquisition, digitization, and processing within the cultural heritage community.

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