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Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics
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Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J: Thermal Management".

Deadline for manuscript submissions: closed (20 December 2021) | Viewed by 34716

Special Issue Editors

Prof. Dr. Tong Seop Kim

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Inha University, Inha-ro 100, Michuhol-gu, Incheon 22212, Republic of Korea
Interests: gas turbine; steam turbine; performance analysis and diagnosis; advanced power and energy systems
Prof. Dr. Jae Su Kwak

E-Mail Website
Guest Editor
School of Aerospace and Mechanical Engineering, Korea Aerospace University, 76 Hanggongdaehang-ro, Deogyang-gu, Goyang 10540, Korea
Interests: gas turbine heat transfer and cooling; heat transfer in propulsion systems

Special Issue Information

Dear Colleagues,

The role of gas turbines in the power industry is becoming increasingly important. The inherent merits of gas turbines, such as their high power density, low emissions, and the highest possible power generation efficiency currently available through the gas turbine combined cycle, have been the major factors in increasing the momentum of their rapid penetration in the power market. In the changing environment of the power industry, where the rapid growth of renewable sources is expected, the demand for gas turbines will continue to be very high because of their advantages, such as rapid startup and shutdown, and excellent load following capability. The current position of gas turbines has been secured by rapid performance evolution during the past few decades, which was enabled by steady advances in performance optimization, heat transfer technologies, especially turbine cooling, and the aerodynamics of primary and secondary air flows. Owing to these aero-thermal technologies, the current state-of-the-art combined cycle has reached over 62% net power generation efficiency. Such technologies will surely be equally important to achieving the ultimate efficiency goal approaching 70%.

This Special Issue invites original research papers to address the latest advances in performance analysis and diagnosis, heat transfer and cooling technologies, and the aerodynamics of major components including the compressor, turbine, and combustor, and secondary air systems. Not only is research on power generation gas turbines encouraged, but that on aero-engines is also welcome.

Potential topics include, but are not limited to:

  • Steady state performance analysis of gas turbines
  • Transient analysis of gas turbines
  • Diagnosis and control of gas turbines
  • Cycle simulation
  • Cycle innovations
  • General heat transfer
  • Cooling of hot parts
  • Film cooling of turbine blades
  • Internal cooling of turbine blades
  • Aerodynamics of the compressor, combustor, and turbine
  • Secondary air systems
  • Sealing technologies
  • Leakage flows

Prof. Tong Seop Kim
Prof. Dr. Jae Su Kwak
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Gas turbine
  • Performance analysis
  • Heat transfer
  • Turbine cooling
  • Aerodynamics.

Published Papers (16 papers)

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Research

16 pages, 27815 KiB  
Article
Influence of a Central Jet on Isothermal and Reacting Swirling Flow in a Model Combustion Chamber
by Egor V. Palkin, Mikhail Yu. Hrebtov, Darya A. Slastnaya, Rustam I. Mullyadzhanov, Luc Vervisch, Dmitriy K. Sharaborin, Aleksei S. Lobasov and Vladimir M. Dulin
Energies 2022, 15(5), 1615; https://0-doi-org.brum.beds.ac.uk/10.3390/en15051615 - 22 Feb 2022
Cited by 7 | Viewed by 1755
Abstract
We studied flow dynamics in a model combustion chamber using Large-eddy simulations (LES) and Particle image velocimetry (PIV) at the Reynolds number Re of 15,000. The swirl is produced using a Turbomeca swirler and air flow, while combustion is supported by a [...] Read more.
We studied flow dynamics in a model combustion chamber using Large-eddy simulations (LES) and Particle image velocimetry (PIV) at the Reynolds number Re of 15,000. The swirl is produced using a Turbomeca swirler and air flow, while combustion is supported by a central methane/air jet. We compared four flow regimes, assessing the effect of the central jet for isothermal and lean reacting conditions. A detailed comparison for isothermal and reactive cases without the central jet is described, validating the LES results against PIV. We observe that unsteady dynamics are governed by global instability in the form of a well-known precessing vortex core (PVC). The central jet slightly changes the dynamics of PVC in the isothermal case where a strong recirculation zone is still formed. However, for the reacting case, the bubble is completely destroyed with no signs of strong vortical structures in the inner shear layer. These observations are confirmed using spectral analysis and proper orthogonal decomposition, describing the contribution of different flow modes in terms of azimuthal harmonics. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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21 pages, 2781 KiB  
Article
A Comparative Feasibility Study of the Use of Hydrogen Produced from Surplus Wind Power for a Gas Turbine Combined Cycle Power Plant
by Min-Jung Pyo, Seong-Won Moon and Tong-Seop Kim
Energies 2021, 14(24), 8342; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248342 - 10 Dec 2021
Cited by 9 | Viewed by 3089
Abstract
Because of the increasing challenges raised by climate change, power generation from renewable energy sources is steadily increasing to reduce greenhouse gas emissions, especially CO2. However, this has escalated concerns about the instability of the power grid and surplus power generated [...] Read more.
Because of the increasing challenges raised by climate change, power generation from renewable energy sources is steadily increasing to reduce greenhouse gas emissions, especially CO2. However, this has escalated concerns about the instability of the power grid and surplus power generated because of the intermittent power output of renewable energy. To resolve these issues, this study investigates two technical options that integrate a power-to-gas (PtG) process using surplus wind power and the gas turbine combined cycle (GTCC). In the first option, hydrogen produced using a power-to-hydrogen (PtH) process is directly used as fuel for the GTCC. In the second, hydrogen from the PtH process is converted into synthetic natural gas by capturing carbon dioxide from the GTCC exhaust, which is used as fuel for the GTCC. An annual operational analysis of a 420-MW-class GTCC was conducted, which shows that the CO2 emissions of the GTCC-PtH and GTCC-PtM plants could be reduced by 95.5% and 89.7%, respectively, in comparison to a conventional GTCC plant. An economic analysis was performed to evaluate the economic feasibility of the two plants using the projected cost data for the year 2030, which showed that the GTCC-PtH would be a more viable option. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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20 pages, 19511 KiB  
Article
On the Flow Structure and Dynamics of Methane and Syngas Lean Flames in a Model Gas-Turbine Combustor
by Vladimir Dulin, Leonid Chikishev, Dmitriy Sharaborin, Aleksei Lobasov, Roman Tolstoguzov, Zundi Liu, Xiaoxiang Shi, Yuyang Li and Dmitriy Markovich
Energies 2021, 14(24), 8267; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248267 - 08 Dec 2021
Cited by 6 | Viewed by 2535
Abstract
The present paper compares the flow structure and flame dynamics during combustion of methane and syngas in a model gas-turbine swirl burner. The burner is based on a design by Turbomeca. The fuel is supplied through injection holes between the swirler blades to [...] Read more.
The present paper compares the flow structure and flame dynamics during combustion of methane and syngas in a model gas-turbine swirl burner. The burner is based on a design by Turbomeca. The fuel is supplied through injection holes between the swirler blades to provide well-premixed combustion, or fed as a central jet from the swirler’s centerbody to increase flame stability via a pilot flame. The measurements of flow structure and flame front are performed by using the stereo particle image velocimetry and OH planar laser-induced fluorescence methods. The measurements are performed for the atmospheric pressure without preheating and for 2 atm with the air preheated up to 500 K. The flow Reynolds numbers for the non-reacting flows at these two conditions are 1.5 × 103 and 1.0 × 103, respectively. The flame dynamics are analyzed based on a high-speed OH* chemiluminescence imaging. It is found that the flame dynamics at elevated conditions are related with frequent events of flame lift-off and global extinction, followed by re-ignition. The analysis of flow structure via the proper orthogonal decomposition reveals the presence of two different types of coherent flow fluctuations, namely, longitudinal and transverse instability modes. The same procedure is applied to the chemiluminescence images for visualization of bulk movement of the flame front and similar spatial structures are observed. Thus, the longitudinal and transverse instability modes are found in all cases, but for the syngas at the elevated pressure and temperature the longitudinal mode is related to strong thermoacoustic fluctuations. Therefore, the present study demonstrates that a lean syngas flame can become unstable at elevated pressure and temperature conditions due to a greater flame propagation speed, which results in periodic events of flame flash-back, extinction and re-ignition. The reported data is also useful for the validation of numerical simulation codes for syngas flames. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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23 pages, 6917 KiB  
Article
Advanced Control to Improve the Ramp-Rate of a Gas Turbine: Optimization of Control Schedule
by Young-Kwang Park, Seong-Won Moon and Tong-Seop Kim
Energies 2021, 14(23), 8024; https://0-doi-org.brum.beds.ac.uk/10.3390/en14238024 - 01 Dec 2021
Cited by 5 | Viewed by 1839
Abstract
As the proportion of power generation using renewable energy increases, it is important to improve the operational flexibility of gas turbines (GTs) for the stability of power grids. Increasing the ramp-rate of GTs is a general solution. However, a higher ramp-rate increases the [...] Read more.
As the proportion of power generation using renewable energy increases, it is important to improve the operational flexibility of gas turbines (GTs) for the stability of power grids. Increasing the ramp-rate of GTs is a general solution. However, a higher ramp-rate increases the turbine inlet temperature (TIT), its rate of change, and the fluctuation of the frequency of produced electricity, which are negative side effects. This study proposes a method to optimize the set-point schedule for a PID controller to improve the ramp-rate while decreasing the negative impacts. The set-point schedule was optimized for a 170-MW class GT using a genetic algorithm to minimize the difference between the value of the process variable and the set-point value of the conventional control. The advanced control reduced the fluctuation of the rotation speed by 20% at the reference ramp-rates (12 MW/min and 15 MW/min). The maximum TIT decreased by 6.3 °C, and its maximum rate of change decreased from 0.7 °C/s to 0.4 °C/s. The advantage of the advanced control becomes more marked as the ramp-rate increases. Even at a much higher ramp-rate (50 MW/min), the advanced control decreased the rotation speed fluctuation by 40% in comparison to the conventional control at the reference ramp-rate. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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13 pages, 5476 KiB  
Article
Effect of Mainstream Velocity on the Heat Transfer Coefficient of Gas Turbine Blade Tips
by Jin Young Jeong, Woojun Kim, Jae Su Kwak, Byung Ju Lee and Jin Taek Chung
Energies 2021, 14(23), 7968; https://0-doi-org.brum.beds.ac.uk/10.3390/en14237968 - 29 Nov 2021
Viewed by 1450
Abstract
This study experimentally investigated the effects of cascade inlet velocity on the distribution and the level of the heat transfer coefficient on a gas turbine blade tip. The tests were conducted in a transient turbine test facility at Korea Aerospace University, and three [...] Read more.
This study experimentally investigated the effects of cascade inlet velocity on the distribution and the level of the heat transfer coefficient on a gas turbine blade tip. The tests were conducted in a transient turbine test facility at Korea Aerospace University, and three cascade inlet velocities—30, 60, and 90 m/s—were considered. The heat transfer coefficient was measured using the transient IR camera technique with a linear regression method, and both the squealer and plane tips were investigated. The results showed that the overall averaged heat transfer coefficient was generally proportional to the inlet velocity. As the inlet velocity is increased from 30 m/s to 60 m/s and 90 m/s, the heat transfer coefficient increased by 11.4% and 25.0% for plane tip, and 26.6% and 64.1% for squealer tip, respectively. However, the heat transfer coefficient near the leading edge of the squealer tip and the reattachment region of the plane tip was greatly affected by the cascade inlet velocity. Therefore, heat transfer experiments for a gas turbine blade tip should be performed under engine simulating conditions. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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18 pages, 11603 KiB  
Article
Large Eddy Simulation of Film Cooling Involving Compound Angle Hole with Bulk Flow Pulsation
by Seung-Il Baek and Joon Ahn
Energies 2021, 14(22), 7659; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227659 - 16 Nov 2021
Cited by 4 | Viewed by 1685
Abstract
The effects of pulsations in the main flow on film cooling from a cylindrical hole with a spanwise injection angle (orientation angle) are analyzed using numerical methods. The hole is located on a flat plate with a 35° inclined injection angle, and the [...] Read more.
The effects of pulsations in the main flow on film cooling from a cylindrical hole with a spanwise injection angle (orientation angle) are analyzed using numerical methods. The hole is located on a flat plate with a 35° inclined injection angle, and the compound angle denotes the orientation and inclination angles. The film cooling flow fields for the sinusoidal flow pulsation of 36 Hz from a cylindrical hole with 0° and 30° orientation angles at the time-averaged blowing ratio of M = 0.5 are simulated via large eddy simulation (LES). The CFD results are validated using the experimental data and compared to the Reynolds-averaged Navier–Stokes (RANS) and URANS results. The results reveal that if the pulsation frequency goes from 0 to 36 Hz, the adiabatic film cooling effectiveness decreases regardless of the compound angle; however, the film cooling for the 30° orientation angle exhibits better performance than that for a simple angle (0°). Moreover, if 36 Hz pulsation is applied, the film cooling effectiveness obtained by unsteady RANS exhibits a large deviation from the experimental data, unlike the LES results. The credibility of the LES results relative to the experimental data is demonstrated by comparing the time-averaged η and the phase-averaged temperature contours. The LES results demonstrate that LES can more accurately predict η than the experimental data; in contrast, URANS results are highly overpredicted around the centerline of the coolant spreading. Thus, LES results are more consistent with the experimental results for the time- and phase-averaged temperature contours than the URANS results. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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17 pages, 6852 KiB  
Article
Large Eddy Simulations on Film Cooling Flow Behaviors with Upstream Turbulent Boundary Layer Generated by Circular Cylinder
by Young Seok Kang, Dong-Ho Rhee, Yu Jin Song and Jae Su Kwak
Energies 2021, 14(21), 7227; https://0-doi-org.brum.beds.ac.uk/10.3390/en14217227 - 02 Nov 2021
Cited by 2 | Viewed by 1519
Abstract
Large eddy simulations on film cooling hole array on a flat plate was carried out to investigate upstream turbulence effect. Circular cylinders were configured to create a turbulent boundary layer and its diameter has been adjusted to generate 13% upstream turbulence intensity in [...] Read more.
Large eddy simulations on film cooling hole array on a flat plate was carried out to investigate upstream turbulence effect. Circular cylinders were configured to create a turbulent boundary layer and its diameter has been adjusted to generate 13% upstream turbulence intensity in the main flow. Due to the small pitch to diameter configuration of the cylinder, two-dimensional LES analysis was carried out in advance and the results showed that LES was an essential method to resolve flow field around and downstream circular cylinder, which was not available in RANS simulations. The three-dimensional LES results showed reasonable agreement in turbulence intensity and normalized velocity distributions along the vertical with measured data. According to the blowing ratio, the cooling flow coverage on the surface along the stream-wise direction was varied and well agreed with measured data. Additionally, upstream boundary flows were partially ingested inside the cooling hole and discharged again near along the centerline of the cooling hole. This accounted for film cooling effectiveness distribution inside the cooling hole surface and along the centerline. The current study revealed that the LES for predicting turbulent boundary layer behaviors due to upstream turbulence generation source was an effective and feasible method. Moreover, the LES effectively resolved flow fields such as film cooling flow behaviors and corresponding film cooling effectiveness distributions. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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18 pages, 9509 KiB  
Article
Numerical Investigation on a Axial Slot Casing Treatment of a Large Circumferential Interval and Small Opening Area
by Zepeng Liu, Guoping Huang and Omer Musa
Energies 2021, 14(19), 6181; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196181 - 28 Sep 2021
Cited by 2 | Viewed by 1373
Abstract
Axial slot casing treatment is a common method to extend the stall margin of a compressor. Based on the mechanism of unsteady flow control, this paper redesigns axial slots with large circumferential interval and small opening area. To test the effect of this [...] Read more.
Axial slot casing treatment is a common method to extend the stall margin of a compressor. Based on the mechanism of unsteady flow control, this paper redesigns axial slots with large circumferential interval and small opening area. To test the effect of this axial slot structure, unsteady numerical simulations were carried out with different slot areas and circumferential intervals. The results show that this novel axial slot casing treatment can significantly improve compressor stall margin. Meanwhile, compared with the traditional axial slot, the efficiency loss is greatly reduced. The flow field analysis shows that the new axial slot structure proposed in this paper can suppress the development of tip leakage vortex and unsteadiness in the tip region at the near stall condition through decreasing the tip loading periodically. Moreover, we find that the slot area is proportional to the improvement of stability margin. Under the same slot area, an excessive number of slots is not conducive to the improvement of the stability margin. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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26 pages, 13497 KiB  
Article
Numerical Investigation into the Effects of Design Parameters on the Flow Characteristics in a Turbine Exhaust Diffuser
by Byung Ju Lee and Jin Taek Chung
Energies 2021, 14(16), 5171; https://0-doi-org.brum.beds.ac.uk/10.3390/en14165171 - 21 Aug 2021
Viewed by 1987
Abstract
In this study, we numerically investigated the effects of design parameters, such as the strut geometry or diffusion angle, on the performance of an industrial turbine exhaust diffuser. Turbine exhaust diffusers are commonly used to change the kinetic energy of exhaust gases from [...] Read more.
In this study, we numerically investigated the effects of design parameters, such as the strut geometry or diffusion angle, on the performance of an industrial turbine exhaust diffuser. Turbine exhaust diffusers are commonly used to change the kinetic energy of exhaust gases from the outlet of turbine stages into the static pressure. The turbine exhaust diffuser investigated in this work consisted of an annular diffuser with five identical struts equally spaced around the front circumference and a conical diffuser with a hub extension at the rear. Four design parameters were considered and several values for each parameter were tested in this study. The aerodynamic performances of the studied diffusers were evaluated according to their pressure recovery coefficients and rates of total pressure loss. Contours for the velocity, pressure, and entropy increase were plotted and compared for the various diffuser shapes. The numerical results showed that the strut thickness and the axially swept angle of the strut significantly influence the aerodynamic performance of the turbine exhaust diffuser, whereas the strut lean angle and the diffuser hade angle are less important. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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15 pages, 7803 KiB  
Article
Thermal Performance of V-Shaped and X-Shaped Ribs in Trapezoidal Cooling Channels
by Wei-Jie Su and Yao-Hsien Liu
Energies 2021, 14(16), 4826; https://0-doi-org.brum.beds.ac.uk/10.3390/en14164826 - 07 Aug 2021
Cited by 1 | Viewed by 1844
Abstract
Convective heat transfer enhancement using rib turbulators is effective for turbine blade internal cooling. Detailed heat transfer measurement of X-shaped ribs in a trapezoidal cooling channel was experimentally conducted using infrared thermography. The novel X-shaped ribs were designed by combining two V-shaped ribs, [...] Read more.
Convective heat transfer enhancement using rib turbulators is effective for turbine blade internal cooling. Detailed heat transfer measurement of X-shaped ribs in a trapezoidal cooling channel was experimentally conducted using infrared thermography. The novel X-shaped ribs were designed by combining two V-shaped ribs, and more secondary flows generated by the X rib delivered higher heat transfer enhancement. The Reynolds numbers in this study were 10,000, 20,000, and 30,000. These ribs were installed on two opposite walls of a trapezoidal channel in a staggered arrangement. The rib pitch-to-height ratios were 10 and 20, and the rib height-to-hydraulic diameter ratio was 0.128. Results indicated that higher heat transfer distribution was observed in the vicinity of the shorter base in the trapezoidal channel. The full X-shaped ribs and the V-shaped ribs demonstrated the highest Nusselt number ratios among all the cases. Although full X-shaped ribs contributed to higher heat transfer improvement due to intensified secondary flows, they also caused significant pressure loss. Therefore, the cutback X-shaped ribs were proposed by removing a segment in the rib at either upstream or downstream region. Consequently, the upstream cutback X-shaped rib and the V-shaped rib produced the highest thermal performance in this trapezoidal channel. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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16 pages, 6710 KiB  
Article
Investigations of Flow and Heat Transfer Characteristics in a Channel Impingement Cooling Configuration with a Single Row of Water Jets
by Min-Seob Shin, Santhosh Senguttuvan and Sung-Min Kim
Energies 2021, 14(14), 4327; https://0-doi-org.brum.beds.ac.uk/10.3390/en14144327 - 18 Jul 2021
Cited by 5 | Viewed by 2845
Abstract
The present study experimentally and numerically investigates the effect of channel height on the flow and heat transfer characteristics of a channel impingement cooling configuration for various jet Reynolds numbers in the range of 2000–8600. A single array consisting of eleven jets with [...] Read more.
The present study experimentally and numerically investigates the effect of channel height on the flow and heat transfer characteristics of a channel impingement cooling configuration for various jet Reynolds numbers in the range of 2000–8600. A single array consisting of eleven jets with 0.8 mm diameter injects water into the channel with 2 mm width at four different channel heights (3, 4, 5, and 6 mm). The average heat transfer coefficients at the target surface are measured by maintaining a temperature difference between the jet exit and the target surface in the range of 15–17 °C for each channel height. The experimental results show the average heat transfer coefficient at the target surface increases with the jet Reynolds number and decreases with the channel height. An average Nusselt number correlation is developed based on 85 experimentally measured data points with a mean absolute error of less than 4.31%. The numerical simulation accurately predicts the overall heat transfer rate within 10% error. The numerical results are analyzed to investigate the flow structure and its effect on the local heat transfer characteristics. The present study advances the primary understanding of the flow and heat transfer characteristics of the channel impingement cooling configuration with liquid jets. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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21 pages, 12495 KiB  
Article
Thermal Analysis and Creep Lifetime Prediction Based on the Effectiveness of Thermal Barrier Coating on a Gas Turbine Combustor Liner Using Coupled CFD and FEM Simulation
by Kanmaniraja Radhakrishnan and Jun Su Park
Energies 2021, 14(13), 3817; https://0-doi-org.brum.beds.ac.uk/10.3390/en14133817 - 24 Jun 2021
Cited by 2 | Viewed by 2257
Abstract
Thermal barrier coating (TBC) plays a vital role in the gas turbine combustor liner (CL) to mitigate the internal heat transfer from combustion gas to the CL and enhance the parent material lifetime of the CL. This present study examined the thermal analysis [...] Read more.
Thermal barrier coating (TBC) plays a vital role in the gas turbine combustor liner (CL) to mitigate the internal heat transfer from combustion gas to the CL and enhance the parent material lifetime of the CL. This present study examined the thermal analysis and creep lifetime prediction based on three different TBC thicknesses, 400, 800, and 1200 μm, coated on the inner CL using the coupled computational fluid dynamics/finite element method. The simulation method was divided into three models to minimize the amount of computational work involved. The Eddy Dissipation Model was used in the first model to simulate premixed methane-air combustion, and the wall temperature of the inner CL was obtained. The conjugate heat transfer simulation on the external cooling flows from the rib turbulator, impingement jet, and cross flow, and the wall temperature of the outer CL was obtained in the second model. The thermal analysis was carried out in the third model using three different TBC thicknesses and incorporating the wall data from the first and second model. The effect of increasing TBC thickness shows that the TBC surface temperature was increased. Thereby, the inner CL metal temperature was decreased due to the TBC thickness as well as the material properties of Yttria Stabilized Zirconia, which has low thermal conductivity and a high thermal expansion coefficient. With the increase in TBC thickness, the average temperature difference between the TBC surface and the inner metal surface increased. In contrast, the average temperature difference between the inner and outer metal surfaces remained nearly constant. The von Mises equivalent stress, based on the material property and thermal expansion coefficient, was determined and used to find the creep lifetime of the CL using the Larson–Miller rupture curve for all TBC thickness cases in order to analyze the thermo-structure. Except in the C-channel, the increasing TBC thickness was found to effectively increase the CL lifespan. Furthermore, the case without TBC was compared with the damaged CL with cracks due to thermal stress, which was prevented by increasing TBC thickness shown in this present study. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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15 pages, 5764 KiB  
Article
A Study on the Leakage Characteristics of a Stepped Labyrinth Seal with a Ribbed Casing
by Min-Seok Hur, Seong-Won Moon and Tong-Seop Kim
Energies 2021, 14(13), 3719; https://0-doi-org.brum.beds.ac.uk/10.3390/en14133719 - 22 Jun 2021
Cited by 7 | Viewed by 2837
Abstract
A new type of stepped seal with a ribbed casing is proposed to efficiently reduce the leakage at the tips of turbine blades. The leakage characteristics of two different types of labyrinth seals (conventional seal vs. ribbed seal) were compared and analyzed through [...] Read more.
A new type of stepped seal with a ribbed casing is proposed to efficiently reduce the leakage at the tips of turbine blades. The leakage characteristics of two different types of labyrinth seals (conventional seal vs. ribbed seal) were compared and analyzed through computational fluid dynamics (CFD) in a wide operating range of pressure ratios and clearances. The analysis showed that the ribbed seal has superior leakage performance to the conventional seal at all clearance sizes. With the same clearance size (S/H = 1.0), the flow function of the ribbed seal was approximately 21.5–42.6% less than that of the conventional seal. Also, different trends of variation in the flow function according to the increase of the clearance were found between the conventional and ribbed seals. The leakage flow inside the labyrinth seal was analyzed to explain the cause of this difference in tendency, and it was confirmed that the added ribs cause collision between the leakage flow and the tooth wall, even with the increase of the clearance. Also, the ribbed seal enables operation at a larger clearance with the same leakage performance when comparing the absolute leakage flow rate of the two seals. In addition, a parametric study on the influence of the rib height and rib inclination angle revealed that the flow function generally decreases as both parameters increase. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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15 pages, 6088 KiB  
Article
Effect of Mainstream Velocity on the Optimization of a Fan-Shaped Film-Cooling Hole on a Flat Plate
by Soo In Lee, Jin Young Jung, Yu Jin Song and Jae Su Kwak
Energies 2021, 14(12), 3573; https://0-doi-org.brum.beds.ac.uk/10.3390/en14123573 - 16 Jun 2021
Cited by 6 | Viewed by 1646
Abstract
In this study, the effect of mainstream velocity on the optimization of a fan-shaped hole on a flat plate was experimentally investigated. The experiment was conducted by changing the forward expansion angle (βfwd), lateral expansion angle (βlat), [...] Read more.
In this study, the effect of mainstream velocity on the optimization of a fan-shaped hole on a flat plate was experimentally investigated. The experiment was conducted by changing the forward expansion angle (βfwd), lateral expansion angle (βlat), and metering length ratio (Lm/D) of the film-cooling hole. A total of 13 cases extracted using the Box–Behnken method were considered to examine the effect of the shape parameters of the film-cooling hole under a 90 m/s mainstream velocity condition, and the results were compared with the results derived under a mainstream velocity of 20 m/s. One density ratio (DR = 2.0) and a blowing ratio (M) ranging from 1.0 to 2.5 were considered, and the pressure-sensitive paint (PSP) technique was applied for the film-cooling effectiveness (FCE). As a result of the experiment, the optimized hole showed a 49.3% improvement in the overall averaged FCE compared to the reference hole with DR = 2.0 and M = 2.0. As the blowing ratio increased, the hole exit area tended to increase, and this tendency was the same as that in the 20 m/s mainstream condition. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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14 pages, 4508 KiB  
Article
Stability Enhancement of a Single-Stage Transonic Axial Compressor Using Inclined Oblique Slots
by Tien-Dung Vuong and Kwang-Yong Kim
Energies 2021, 14(9), 2346; https://0-doi-org.brum.beds.ac.uk/10.3390/en14092346 - 21 Apr 2021
Cited by 4 | Viewed by 1751
Abstract
A casing treatment using inclined oblique slots (INOS) is proposed to improve the stability of the single-stage transonic axial compressor, NASA Stage 37, during operation. The slots are installed on the casing of the rotor blades. The aerodynamic performance was estimated using three-dimensional [...] Read more.
A casing treatment using inclined oblique slots (INOS) is proposed to improve the stability of the single-stage transonic axial compressor, NASA Stage 37, during operation. The slots are installed on the casing of the rotor blades. The aerodynamic performance was estimated using three-dimensional steady Reynolds-Averaged Navier-Stokes analysis. The results showed that the slots effectively increased the stall margin of the compressor with slight reductions in the pressure ratio and adiabatic efficiency. Three geometric parameters were tested in a parametric study. A single-objective optimization to maximize the stall margin was carried out using a Genetic Algorithm coupled with a surrogate model created by a radial basis neural network. The optimized design increased the stall margin by 37.1% compared to that of the smooth casing with little impacts on the efficiency and pressure ratio. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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19 pages, 26129 KiB  
Article
Analysis of Multi-Stream Fuel Injector Flow Using Zonal Proper Orthogonal Decomposition
by Daniel Butcher and Adrian Spencer
Energies 2021, 14(6), 1789; https://0-doi-org.brum.beds.ac.uk/10.3390/en14061789 - 23 Mar 2021
Cited by 4 | Viewed by 1884
Abstract
The 3-component velocity distribution of two lean-burn gas turbine fuel injectors are measured at a planar location near and parallel to the injector outlet. The two injectors are nominally the same design, but one features blocked central passages to study the effects of [...] Read more.
The 3-component velocity distribution of two lean-burn gas turbine fuel injectors are measured at a planar location near and parallel to the injector outlet. The two injectors are nominally the same design, but one features blocked central passages to study the effects of the presence of multi-streams and reveal the single stream characteristics embedded within the multi-stream configuration. Stereoscopic particle image velocimetry is used in an isothermal, non-reacting water analogue flow facility at an engine relevant Reynolds number. The velocity data is analysed using proper orthogonal decomposition (POD) and the work introduces the concept of Zonal POD. This is the splitting of the velocity field into zones prior to the calculation of POD modes to better identify prominent structures and features associated with each zone. Because modes are sorted by the area averaged energy contribution, zoning of a velocity field of interest may change the individual modes and will almost certainly change their order for anything other than trivial flow fields. Analysis of ensemble average and velocity fluctuation profiles reveals a radial shift outboard of the mains flow with the presence of the pilot as well as a general increase in RMS across the intermediate region between the pilot and mains flows. Analysis of POD temporal coefficients in the frequency domain reveals a low-frequency peak is evident in the mains flow region, but which may be affected by the presence of pilot flow. Furthermore, application of the ZPOD technique results in a closer representation of the velocity data for a given number of modes. This shows the behaviour of the unsteady pilot flow and reveals that a significant proportion of the fluctuating energy, RMS, is caused by this characteristic. Full article
(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)
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