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New Insights of Gas Turbine Cooling Systems

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

Deadline for manuscript submissions: closed (20 April 2023) | Viewed by 19495

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Special Issue Editors

Dr. Xueying Li

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Guest Editor

Institute of Gas Turbine, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
Interests: aero-thermal dynamics in gas turbines; gas turbine heat transfer and cooling technology; film cooling; CFD

Prof. Dr. Jing Ren

E-Mail Website
Guest Editor

Department of Energy and Power Engineering, Tsinghua University, Beijing 10084, China
Interests: aero-thermal dynamics in gas turbines; vane/blade cooling; conjugate heat transfer

Special Issue Information

Dear Colleagues,

Gas turbines (GTs) are a proven technology for well-established power density, reliability, and safety. As a result of the increasing demand for the reduction in CO2 emissions and fuel usage, it remains of high interest to increase the efficiency of gas turbines. The thermal efficiency of gas turbines is directly related to the turbine inlet temperature. The challenge proposed by the issue of the temperature of component metals drastically exceeding their permissible limits, which significantly reduces the component’s lifespan, is being addressed by an acknowledgment of the required use of cooling technologies in gas turbine hot components.

The cooling system has been extensively developed over the years, transitioning from a single internal cooling system with smooth passages to a very complex combined cooling system with film cooling properties, impingement cooling, and heat transfer augmentation with ribs and pin-fins. The latest technology aims to obtain the highest overall cooling effect with the least consequences on the performance of the thermodynamic cycle.

Advanced cooling strategies to further improve the effectiveness of cooling include the optimization of existing methods and the transition to new methodologies. The optimization of existing methods can be implemented from a system perspective, i.e., the thermal management as well as performance improvement of a single method. With the development of materials and manufacturing methods, such as the ceramic matrix composite (CMC) and additive manufacturing (AM), the previous limitations of cooling strategies by material and manufacturing constraints are diminished. These developments provide the possibility for innovative cooling methodologies to be incorporated into gas turbines.

Novel insights into the GT cooling system can accelerate the ongoing fundamental physical research on advanced cooling strategies and promote the relevant innovative cooling technologies to a higher technology readiness level. Research in this area plays a remarkable and vital role in enabling higher turbine inlet temperatures, lowering the consumption of cooling flows, and thereby yielding increased thermodynamic cycle efficiency, while meeting gas turbine life requirements.

The current Special Issue aims to unite innovative developments and collaborations in relation to the novel insights into gas turbine cooling systems.

The potential topics include, but are not limited to, the following areas:

Advances in GT cooling (review paper);
New concept cooling systems in GTs;
Thermal management in GTs;
Innovative cooling;
Additive manufacture-based cooling technology;
CMC-based cooling technology;
Novel film cooling;
Novel internal convective cooling;
Micro cooling;
Double wall cooling;
Advanced experimental techniques in GT cooling;
Aero-thermal-mechanical analysis in cooling systems;
Advanced analytical methods in GT cooling.

Dr. Xueying Li
Prof. Dr. Jing Ren
Guest Editors

Manuscript Submission Information

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Keywords

gas turbine
cooling system
thermal management
combustor cooling
turbine cooling
blade/vane cooling
novel cooling
film cooling
internal cooling
micro cooling
double wall cooling
conjugate heat transfer
experimental/analytical methods

Published Papers (7 papers)

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Research

Jump to: Review

25 pages, 14033 KiB

Open AccessArticle

Large Eddy Simulation of Rotationally Induced Ingress and Egress around an Axial Seal between Rotor and Stator Disks

by Sabina Nketia, Tom I-P. Shih, Kenneth Bryden, Richard Dalton and Richard A. Dennis

Energies 2023, 16(11), 4354; https://doi.org/10.3390/en16114354 - 26 May 2023

Cited by 1 | Viewed by 868

Abstract

In gas turbines, the hot gas exiting the combustor can have temperatures as high as 2000 °C, and some of this hot gas enter into the space between the stator and rotor disks (wheelspace). Since the entering hot gas could damage the disks, its ingestion must be minimized. This is carried out by rim seals and by introducing a cooler flow from the compressor (sealing flow) into the wheelspace. Ingress and egress into rim seals are driven by the stator vanes, the rotor and its rotation, and the rotor blades. This study focuses on the ingress and egress driven by the rotor and its rotation. This is carried out by performing wall-resolved large eddy simulation (LES) around an axial seal in a rotor–stator configuration without vanes and blades. Results obtained show the mechanisms by which the rotor and its rotation induce ingress, egress, and flow trajectories. Kelvin–Helmholtz instability was found to create a wavy shear layer and displacement thickness that produces alternating regions of high and low pressures around the rotor side of the seal. Vortex shedding on the backward-facing side of the seal and its impingement on the rotor side of the seal also produces alternating regions of high and low pressures. The locations of the alternating regions of high and low pressures were found to be statistically stationary and to cause ingress to start on the rotor side of the seal. Vortex shedding and recirculating flow in the seal clearance also cause ingress by entrainment. With the effects of the rotor and its rotation on ingress and egress isolated, this study enables the effects of stator vanes and rotor blades to be assessed. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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23 pages, 13307 KiB

Open AccessArticle

Improved Thermal Performance of a Serpentine Cooling Channel by Topology Optimization Infilled with Triply Periodic Minimal Surfaces

by Kirttayoth Yeranee, Yu Rao, Li Yang and Hao Li

Energies 2022, 15(23), 8924; https://doi.org/10.3390/en15238924 - 25 Nov 2022

Cited by 2 | Viewed by 1841

Abstract

The present study utilizes a density-based topology optimization method to design a serpentine channel under turbulent flow, solving a high pressure loss issue and enhancing heat transfer capability. In the topology optimization, the k–ε turbulence model is modified by adding penalization terms to reveal turbulence effects. Heat transfer modeling is included by setting the modified energy equation with additional terms related to topology optimization. The main objective is to minimize pressure loss while restricting heat transfer. The 2D simplified model is topologically optimized. Then, the optimal solution with intermediate results is extruded in the 3D system and interpreted with triply periodic minimal surfaces (TPMS) to further enhance heat transfer performance. Compared to the baseline serpentine channel, the optimized model infilled with the diamond-TPMS structure lowers pressure loss by 30.8% and significantly enhances total heat transfer by up to 45.8%, yielding thermal performance of 64.8% superior to the baseline. The temperature uniformity is also improved. The simulation results show that the curvatures in the optimized model with diamond-TPMS structure eliminate the large recirculation flow and low heat transfer regions. This model diminishes the effect of Dean’s vortices but promotes high turbulent kinetic energy, leading to better uniform flow and heat transfer distributions. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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20 pages, 9905 KiB

Open AccessArticle

Errors Incurred in Local Convective Heat Transfer Coefficients Obtained through Transient One-Dimensional Semi-Infinite Conduction Modeling: A Computational Heat Transfer Study

by Prashant Singh

Energies 2022, 15(19), 7001; https://doi.org/10.3390/en15197001 - 23 Sep 2022

Cited by 2 | Viewed by 1178

Abstract

In typical turbulent flow problems, detailed heat transfer coefficient (h) maps obtained through short-duration experiments are based on inverse heat transfer methods that take the wall temperatures measured via liquid crystals or infrared thermography as input, and an error minimization routine is adopted to determine the best value of h that satisfies the wall temperature temporal evolution under a certain change in fluid temperature. A common practice involves modeling the solid as a one-dimensional semi-infinite medium by selecting the solid material that has low thermal conductivity and low thermal diffusivity. However, in certain flow scenarios, the neglection of the lateral heat diffusion may lead to significant errors in the deduced h values. It is imperative to understand the reasons behind large errors that may be incurred by using the 1D heat conduction assumption in order to accurately determine high-resolution h maps for better heat exchanger designs in a wide range of thermal management applications. This paper presents a computational heat transfer study on different jet impingement scenarios to demonstrate the errors incurred in the determination of h when calculated under the assumption of one-dimensional (1-d) heat conduction into a solid. To this end, three different cases are studied: (a) single jet, (b) array jet (theoretical distribution), (c) array jet (experimental distribution), along with three different mainstream temperature evolution profiles representing step change, moderately fast transient and slow transient nature of flow driving the heat transfer in the solid. A known distribution of heat transfer coefficient (“true h”) for each of the three cases is considered, and three-dimensional transient heat diffusion equations were solved to populate temperatures of each node in the solid at every time step. It is found that stagnation zones’ h_1d calculations were lower than the “true h” while the low heat transfer zones exhibited significantly higher h_1d compared to the “true h”. For the array jet (experimental distribution) case, it was observed that errors can be as high as 10% in certain low heat transfer zones. Different data reduction procedures, configurations, and conditions explored in this study indicate that a suitable balance can be achieved if shorter time durations in transient experiments are used as a reference for tracking in h_1d calculations to keep the deviations from the “true h” low. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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30 pages, 10749 KiB

Open AccessArticle

Numerical Investigation of Flow and Heat Transfer in Rectangular Microchannels with and without Semi-Elliptical Protrusions

by Haiou Sun, Hao Fu, Lanyi Yan, Hongfei Ma, Yigang Luan and Franco Magagnato

Energies 2022, 15(13), 4927; https://doi.org/10.3390/en15134927 - 5 Jul 2022

Cited by 3 | Viewed by 1555

Abstract

Micro-cooling is a growing trend in the field of turbine blade cooling. Technical difficulties in the experiments of large-aspect-ratio rectangular microchannels that are commonly used in the turbine blades cause the rareness of related literature. In this study, the flow characteristics and heat transfer performance of the microchannels with and without semi-ellipsoidal protrusions, whose height is 0.6 mm and width is 9 mm, are numerically investigated. In the microchannel without protrusions, when 2214 < Re < 3589, the velocity has a Λ-shaped distribution, resulting in a Λ-shaped Nu distribution on the wall. When Re > 3760, it is worth noting that from the sidewall to the middle of the channel, Nu first decreases and then increases. In the microchannel with protrusions, when Re < 1214, the turbulence formed by the protrusion is almost all behind it and does not spread to both sides. When 1214 < Re < 2374, the turbulence caused by the protrusions gradually spreads to the middle and both sides of the channel with the increase in Re. When 2374 < Re < 3815, the turbulence caused by two columns of protrusions meet in the middle of the channel and forms stronger turbulence downstream. When Re > 3815, the flow is all turbulent. The protrusions enhance the irreversibility of heat transfer and friction. The performance evaluation criteria (PEC) increases first and then decreases with Re and the maximum value is 1.80 at Re = 2004. In this work, the details that are difficult to obtain in experiments are fully analyzed to provide suggestions for the design of micro-cooling structures in gas turbine blades. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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15 pages, 6473 KiB

Open AccessArticle

Numerical Investigation of the Effects of Lattice Array Structures on Film Cooling Performance

by Qiang Fu, Xiaobo Luo, Wei Chen and Minking K. Chyu

Energies 2022, 15(13), 4711; https://doi.org/10.3390/en15134711 - 27 Jun 2022

Cited by 1 | Viewed by 1228

Abstract

To better understand the mechanism influencing the periodic lattice structures in gas turbine blade cooling, these numerical simulations present a systematic comparison of the effects in cases involving pin-fin, Kagome, and BCC lattice arrays on film-cooling effectiveness under three blowing ratios (i.e., M = 0.5, 1.0, and 1.5). The results indicate that the introduction of lattice array structures improves film-cooling effectiveness within the whole streamwise range, especially downstream of the film hole. With an increase in the blowing ratio, the superiority of lattice array structures relative to those without a lattice becomes increasingly evident. The local film-cooling effectiveness can be increased, to a maximum of about 100%, under a blowing ratio of 1.5. The secondary flow induced by the lattice array structure at the internal flow channel increases the TKE and accelerates the development of vortices in the film cooling hole. Using the lattice array model, the improvement of the Kagome and BCC lattice arrays in terms of film cooling is better than those of pin-fins. In addition, the effect of lattice arrays on film-cooling effectiveness is different at various blowing ratios, and the lattice array structures have little impact on the film cooling at a relatively low blowing ratio. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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Review

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29 pages, 23087 KiB

Open AccessReview

A Review of Recent Investigations on Flow and Heat Transfer Enhancement in Cooling Channels Embedded with Triply Periodic Minimal Surfaces (TPMS)

by Kirttayoth Yeranee and Yu Rao

Energies 2022, 15(23), 8994; https://doi.org/10.3390/en15238994 - 28 Nov 2022

Cited by 34 | Viewed by 6783

Abstract

Triply periodic minimal surfaces (TPMS) have shown better mechanical performance, mass transfer, and thermal conductivity than conventional and strut-based structures, which have been employed in different disciplines. Most of the literature investigates different TPMS topologies in cooling channels to enhance thermal performance due to the smooth curvature and large surface area. However, a deeper investigation of the effects of TPMS design variables and the thermal performance advantages of cooling channels is required. This review details the effects of TPMS design variables, i.e., porosity, wall thickness, and unit cell size, on flow and heat transfer enhancement. It is found that varying the design variables significantly changes the flow and heat transfer characteristics. Also, by comparing TPMS and conventional cooling structures, it is found that most TPMS structures show better thermal performance than other strategies. Moreover, different fabrication methods for TPMS-based cooling channels in recent investigations are collected and discussed. In light of the reviewed literature, recommendations for future research suggest that more experimental and numerical studies on the flow and heat transfer for different cooling applications are needed. Therefore, this review serves as a reference tool to guide future studies on the flow and heat transfer of TPMS-based cooling channels. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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35 pages, 11986 KiB

Open AccessReview

Evolution of Turbine Cooled Vanes and Blades Applied for Large Industrial Gas Turbines and Its Trend toward Carbon Neutrality

by Kenichiro Takeishi

Energies 2022, 15(23), 8935; https://doi.org/10.3390/en15238935 - 25 Nov 2022

Cited by 11 | Viewed by 5332

Abstract

Photovoltaics and wind power are expected to account for a large share of power generation in the carbon-neutral era. A gas turbine combined cycle (GTCC) with an industrial gas turbine as the main engine has the ability to rapidly start up and can follow up to load fluctuations to smooth out fluctuations in power generation from renewable energy sources. Simultaneously, the system must be more efficient than today’s state-of-the-art GTCCs because it will use either Carbon dioxide Capture and Storage (CCS) when burning natural gas or hydrogen/ammonia as fuel, which is more expensive than natural gas. This paper describes the trend of cooled turbine rotor blades used in large industrial gas turbines that are carbon neutral. First, the evolution of cooled turbine stationary vanes and rotor blades is traced. Then, the current status of heat transfer technology, blade material technology, and thermal barrier coating technology that will lead to the realization of future ultra-high-temperature industrial gas turbines is surveyed. Based on these technologies, this paper introduces turbine vane and blade cooling technologies applicable to ultra-high-temperature industrial gas turbines for GTCC in the carbon-neutral era. Full article

(This article belongs to the Special Issue New Insights of Gas Turbine Cooling Systems)

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