Review
Thermodynamics
Camilo F. Silva
Summary: It is understood that the behavior of a combustion system can be analyzed by studying how the flame dynamics perturb its natural acoustic modes. However, experimental evidence shows that the frequency of unstable thermoacoustic modes sometimes deviates from the natural acoustic frequencies of the system. The intrinsic thermoacoustic (ITA) feedback loop has been recognized as a responsible mechanism in some cases, and theoretical frameworks and experiments have contributed to understanding the behavior of ITA instabilities.
PROGRESS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Energy & Fuels
Mehmet Kapucu, Jim B. W. Kok
Summary: This paper introduces a new method for deriving the Flame Transfer Function (FTF) from CFD predictions using a discrete multi-frequency sinusoidal fuel flow excitation method. The CFD-based FTF result matches well with experimental data for time delay but only up to 400 Hz for the gain. A novel continuous correlation function is computed based on discrete frequencies to improve the accuracy of the FTF gain. The stability map shows two identical eigenfrequencies below 600 Hz according to both the experiment and CFD-based FTF.
Article
Thermodynamics
Jeongwon Kim, Mitsunori Isono, Toshihiko Saito
Summary: Thermoacoustic instabilities in combustors are nonlinear processes with multiple peaks in the spectrum. This study investigates the dynamic relationship between the fundamental azimuthal instabilities and its first harmonic. It finds that the interaction of the fundamental azimuthal mode produces higher order azimuthal modes and an axial mode in the harmonic. Neglecting this axial mode may result in inaccurate estimation of maximum pressure and potential safety concerns.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Antonio L. Sanchez, Jaime Carpio, Forman A. Williams
Summary: A simplified chemical-kinetic mechanism is used to numerically investigate the pulsating dynamics of fuel-rich hydrogen-air flames, showing unexpectedly good accuracy in predicting flame dynamics, critical conditions at bifurcations, and nonlinear dynamics encountered for phi > phi(c).
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Dan Zhao
Summary: In this study, the dynamic response of a swirling thermoacoustic combustor to acoustic perturbations is experimentally investigated. The flame describing function (FDF) is obtained, and further approximation is performed for system reduction. It is found that an 8th order reduction is sufficient for studying the self-excited combustion instability in swirling thermoacoustic combustors.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Thermodynamics
Shiquan Shan, Jialu Tian, Binghong Chen, Yanwei Zhang, Zhijun Zhou
Summary: This study reveals the advantages of photo-thermal energy cascading conversion over single thermal energy or radiative energy conversion. It analyzes the potential of the cascade conversion with different power generation units and considers future research outlook. The results show that cascade conversion is critical for high-temperature conditions, with oxy-fuel combustion being more suitable. Depending on the technology conditions, efficiency can be increased by more than 20% points for ultra-supercritical units, 15% points for combined cycle units, and over 30% points for small-parameter organic Rankine cycle units.
Article
Engineering, Aerospace
Yiheng Guan, Sid Becker, Dan Zhao, Jingyuan Xu, Mohammad Shahsavari, Jorg Schluter
Summary: In this work, a 2D numerical model is developed to simulate a Y-shaped bifurcating combustor with a Helmholtz resonator. Propane is used as fuel and burnt with air. Experimental measurements validate the numerical findings, showing good agreement in frequency and amplitude of the dominant mode.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Mitchell L. Passarelli, Askar Kazbekov, Victor Salazar, Krishna Venkatesan, Adam M. Steinberg
Summary: This study experimentally explores the effects of external forcing on a turbulent, liquid-fuelled, swirl-stabilized gas turbine combustor operating at approximately 1 MPa. The dynamics and coupling between hydrodynamics, flame dynamics, and acoustics were compared for different forcing amplitudes while keeping the forcing frequency fixed. It was found that the pressure fluctuations followed the phase-locking route to synchronization, contrary to expectations from synchronization theory.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Won Joon Song, Dong -Jin Cha
Summary: This study examines the strength of the coupling between the acoustic field and thermal field in a combustor by analyzing the coherence function between dynamic pressure and heat release rate signals. The results reveal decoupling of the two fields during stable combustion and linear interdependence between the signals at the combustor's acoustic eigenfrequencies during unstable combustion. The formation of interdependence precedes the onset of limit cycle oscillation, suggesting its role in combustion instability.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Yu Guan, Larry K. B. Li, Hyunwook Jegal, Kyu Tae Kim
Summary: We experimentally studied the effect of rotational asymmetries in flame response distribution on thermoacoustic oscillations in a network of four combustors. Different nozzle combinations were used to create the asymmetries. By analyzing the acoustic interactions between combustors, we observed various modal patterns and collective states. This study demonstrates the potential use of rotational asymmetries for passive control of thermoacoustic modes in combustion systems.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Xuanqi Liu, Hangxu Zhou, Yufeng Lai, Yang Zhang
Summary: Thermoacoustic instability is a major concern in various industrial combustion systems, which can cause combustion problems and structural damage. This study investigates the effects of different system parameters in a Rijke tube and explores the system characteristics using time-domain analysis methods.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Engineering, Aerospace
Guanyu Xu, Peijin Liu, Wen Ao, Zhuopu Wang, Bingning Jin
Summary: This paper investigates the nonlinear instabilities caused by small disturbances in solid rocket motors through numerical simulation, analyzing the coupling mechanism between oscillators and discussing the effects of disturbances with different amplitudes and frequencies. Additionally, the study explores the evolution of limit cycle states with varying disturbance amplitudes and suggests that systems are prone to evolve into limit cycle states when small disturbance frequencies are commensurate with acoustic modal frequencies.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Yuanzhe Liu, Peijin Liu, Zhuopu Wang, Wen Ao, Yu Guan
Summary: This paper provides numerical proof of the existence of intermittent routes before and after thermoacoustic instability in a liquid rocket engine. The study shows that with an increase in oxidizer inlet temperatures, the system dynamics experience a shift from combustion noise to thermoacoustic instability through intermittent oscillation, and then a bifurcation back to combustion noise states via intermittency. The study also finds that a decrease in the equivalence ratio accelerates the onset of thermoacoustic instability. The findings provide insights into the underlying physical mechanism of the frequency-locking phenomenon and the migration of the flame anchor point.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Stephane Boulal, Aurelien Genot, Jean-Michel Klein, Yves Fabignon, Axel Vincent-Randonnier, Vladimir Sabelnikov
Summary: This study investigates the combustion dynamics of a methane/air premixed flame in a ducted combustor with a backward-facing step. Spectral analysis of high-speed recordings reveals that the flame dynamics are governed by two main components: an acoustic longitudinal resonance and a hydrodynamic instability caused by the recirculation region behind the step. When the frequencies associated with these mechanisms are close, a hydro-acoustic instability is established, leading to flame flashback. An acoustic analysis of the combustor also identifies an acoustic velocity anti-node at the step, exacerbating the flame fluctuations. The flashback motion is found to be intermittent and accompanied by the stochastic generation of an autoignition front. [Citation] ©2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Minwoo Lee, Kyu Tae Kim, Vikrant Gupta, Larry K. B. Li
Summary: This study successfully performed output-only system identification on a turbulent lean-premixed combustor using inherent turbulence-induced noise dynamics, predicting thermoacoustic instability in the combustion system and providing new pathways for the development of early warning indicators.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Engineering, Aerospace
Rafael L. Rubin, Dan Zhao
Summary: The thrust formula of the actuator disk model was expanded and divided into two parts to show that propellers at incidence have both an axial and a wing lift equivalent component. Wind tunnel tests on a two-bladed propeller revealed that the wing component increases with airflow velocity and angle of incidence, while the axial component decreases with velocity.
Article
Energy & Fuels
Jianqin Fu, Lianhua Zhong, Dan Zhao, Qi Liu, Jun Shu, Feng Zhou, Jingping Liu
Summary: The study investigates the addition of hydrogen to LMG engine, finding that as hydrogen energy fraction (HEF) increases, combustion rate and cylinder pressure increase, while indicated thermal efficiency reaches a maximum between 8% and 12% HEF. Although hydrogen addition can increase combustion rate of the mixture gas, it also increases the detonation trend.
Article
Engineering, Aerospace
Zhuming Rao, Ruichao Li, Bo Zhang, Bing Wang, Dan Zhao, Muhammad Saqib Akhtar
Summary: In this study, the dynamics of pressure oscillations and flame behaviors in a premixed swirl-stabilized combustor were experimentally investigated. Different combustion states were distinguished based on acoustic pressures and flame dynamics. The use of permutation entropy and proper orthogonal decomposition proved effective in analyzing signal complexities and spatial images of chemiluminescence.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Di Guan, Dakun Sun, Ruize Xu, Daniel Bishop, Xiaofeng Sun, Siling Ni, Juan Du, Dan Zhao
Summary: Experimental investigations on dynamic stall phenomena in a single-stage axial compressor were conducted using aeroacoustic measurements, revealing that the compressor stall corresponds to a low-frequency intrinsic mode and an increase in the dominant acoustic modes during stall. Traditional signal analysis methods did not provide any warning precursors, while advanced signal processing techniques such as EMD and POD analysis showed precursors before stall. CW transform could give a 0.05 s warning precursor.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Zhuming Rao, Ruichao Li, Bo Zhang, Bing Wang, Dan Zhao, Mohammad Shahsavari
Summary: Experimental measurements were conducted on a swirl-stabilized combustor to investigate its nonlinear dynamic characteristics under acoustic excitations. The results showed that the combustor experiences frequency locking and high amplitude oscillations when the excitation frequency is close to the natural frequency, as well as super-harmonic resonances.
FLOW TURBULENCE AND COMBUSTION
(2021)
Article
Mechanics
Mohammad Shahsavari, Bing Wang, Bo Zhang, Guanyu Jiang, Dan Zhao
Summary: Large eddy simulations were used to study the response of a supercritical round jet to various excitation modes. Results showed that excitations significantly enhance turbulent mixing, pitch distance, and penetration depth of coherent structures, but also de-energize the structures and reduce three-dimensionality. Dual varicose/flapping excitations had the highest impact on jet development and cross-section shape. Excitations also greatly reduced potential core length, especially under flapping and dual mode excitations.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Aerospace
Yong Chen, Yongchao Sun, Dan Zhao
Summary: This paper investigates the intrinsic thermoacoustic feedback and its interaction with cavity acoustic resonance in swirling flame combustors. The phase shift between acoustic and vortical waves plays a crucial role in determining the stability of the system.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Hui Guo, Minle Wu, Yibin Zhu, Qiwei Li, Keyu Weng, Yange Suo, Yanghui Ye, Yuanjun Tang, Zhigeng Fan, Guoneng Li, Youqu Zheng, Dan Zhao, Zhiguo Zhang
Summary: The effect of acoustic energy on soot suppression in an acetylene-air diffusion flame was experimentally studied, showing a linear increase in suppression efficiency with increasing acoustic energy. Different acoustic waveforms resulted in similar acoustic energy levels for achieving the same soot suppression effect. Acoustic waves caused periodic stretching and compressing of the flame, with a fluctuation velocity above 2 m/s leading to 50% suppression efficiency, but increasing premixed levels reduced flame height and fluctuation velocity.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Xinjian Chen, Junwei Li, Dan Zhao, Muhammad Tahir Rashid, Xinyuan Zhou, Ningfei Wang
Summary: The experimental investigation in this work reveals that foamed porous media significantly enhance heat transfer efficiency in meso-scale burners, showing notable impacts on flame structure and temperature distribution.
Article
Thermodynamics
Siliang Ni, Dan Zhao, Mathieu Sellier, Junwei Li, Xinjian Chen, Xinyan Li, Feng Cao, Weixuan Li
Summary: This study compared the thermal performance and efficiency of unconventional T- and Y-shaped micro-combustors with the traditional I-shaped one. Results showed significant improvements in thermal performance and efficiency for T- and Y-shaped combustors under the same conditions. Optimization of parameters can enhance combustion efficiency.
Article
Chemistry, Applied
Tao Cai, Yuze Sun, Dan Zhao
Summary: This study aims to improve the energy conversion efficiency of a thermo-photo-voltaic system by optimizing combustor performance through the use of staggered bluff-bodies. The implementation of staggered bluff-bodies significantly enhances heat transfer performance and increases mean wall temperature. Results also show that the equivalence ratio and dimensions of the staggered bluff-bodies have a significant impact on system performance.
FUEL PROCESSING TECHNOLOGY
(2021)
Review
Engineering, Aerospace
Xiaohuan Zhao, Limin Su, Jiang Jiang, Wenyu Deng, Dan Zhao
Summary: This paper summarizes and studies the heat flow effects on the thermal performance of micro-channel oscillating heat pipes (MCOHPs), revealing the thermal performance improvements using different working fluids such as nano-fluids, gases, single liquids, mixed liquids, surfactants, and self-humidifying fluids. The use of graphene nano-fluids can reduce the thermal resistance by 83.6% and enhance the maximum thermal conductivity by 105%. Gravity and flow characteristics also have an impact on the heat flow. The study of heat flow effects on the thermal performance of MCOHPs contributes to exploring aerospace applications in depth.
Article
Engineering, Aerospace
Zhaoyang Wang, Dan Zhao, Yunfeng Cao
Summary: This research presents an enhancement algorithm for low-light airborne images based on the camera response model and Retinex theory, which effectively improves the brightness of low-illumination images and achieves better performance in obstacle detection.
Article
Engineering, Aerospace
Zhaoyang Wang, Dan Zhao, Yunfeng Cao
Summary: This paper proposes a novel vision-based autonomous landing navigation scheme for night-time autonomous landing of fixed-wing UAV. The proposed algorithm includes visible and infrared image fusion, improved Faster R-CNN based runway detection, and relative attitude and position estimation for the UAV.
Article
Engineering, Aerospace
Yuze Sun, Dan Zhao, Xiaowei Zhu
Summary: In this study, 3D URANS simulations were used to investigate the combustion-sustained thermoacoustic instabilities in a swirl combustor. The effects of swirling number, inlet air flow rate, and inlet temperature on the amplitudes and frequencies of oscillations were examined. It was found that amplitude increases with swirling number and air flow rate, but decreases with inlet temperature; dominant frequency increases with swirling number and air flow rate, but has a complex relationship with inlet temperature.
Article
Energy & Fuels
Shitong Fang, Houfan Du, Tao Yan, Keyu Chen, Zhiyuan Li, Xiaoqing Ma, Zhihui Lai, Shengxi Zhou
Summary: This paper proposes a new type of nonlinear VIV energy harvester (ANVEH) that compensates for the decrease in peak energy output at low wind speeds by introducing an auxiliary structure. Theoretical and experimental results show that ANVEH performs better than traditional nonlinear VIV energy harvesters under various system parameter variations.
Article
Energy & Fuels
Wei Jiang, Shuo Zhang, Teng Wang, Yufei Zhang, Aimin Sha, Jingjing Xiao, Dongdong Yuan
Summary: A standardized method was developed to evaluate the availability of solar energy resources in road areas, which combined the Analytic Hierarchy Process (AHP) and the Geographic Information System (GIS). By analyzing critical factors and using a multi-indicator evaluation method, the method accurately evaluated the utilization of solar energy resources and guided the optimal location selection for road photovoltaic (PV) projects. The results provided guidance for the application of road PV projects and site selection for route corridors worldwide, promoting the integration of transportation and energy.
Article
Energy & Fuels
Chang Liu, Jacob A. Wrubel, Elliot Padgett, Guido Bender
Summary: The study investigates the effects of coating defects on the performance of the anode porous transport layer (PTL) in water electrolyzers. The results show that an increasing fraction of uncoated regions on the PTL leads to decreased cell performance, with continuous uncoated regions having a more severe impact compared to multiple thin uncoated strips.
Article
Energy & Fuels
Marcos Tostado-Veliz, Xiaolong Jin, Rohit Bhakar, Francisco Jurado
Summary: In this paper, a coordinated charging price mechanism for clusters of parking lots is proposed. The research shows that enabling vehicle-to-grid characteristics can bring significant economic benefits for users and the cluster coordinator, and vehicle-to-grid impacts noticeably on the risk-averse character of the uncertainty-aware strategies. The developed pricing mechanism can reduce the cost for users, avoiding to directly translate the energy cost to charging points.
Article
Energy & Fuels
Duan Kang
Summary: Building an energy superpower is a key strategy for China and a long-term goal for other countries. This study proposes an evaluation system and index for measuring energy superpower, and finds that China has significantly improved its ranking over the past 21 years, surpassing other countries.
Article
Energy & Fuels
Fucheng Deng, Yifei Wang, Xiaosen Li, Gang Li, Yi Wang, Bin Huang
Summary: This study investigated the synergistic blockage mechanism of sand and hydrate in gravel filling layer and the evolution of permeability in the layer. Experimental models and modified permeability models were established to analyze the effects of sand particles and hydrate formation on permeability. The study provided valuable insights for the safe and efficient exploitation of hydrate reservoirs.
Article
Energy & Fuels
Hao Wang, Xiwen Chen, Natan Vital, Edward Duffy, Abolfazl Razi
Summary: This study proposes a HVAC energy optimization model based on deep reinforcement learning algorithm. It achieves 37% energy savings and ensures thermal comfort for open office buildings. The model has a low complexity, uses a few controllable factors, and has a short training time with good generalizability.
Article
Energy & Fuels
Moyue Cong, Yongzhuo Gao, Weidong Wang, Long He, Xiwang Mao, Yi Long, Wei Dong
Summary: This study introduces a multi-strategy ultra-wideband energy harvesting device that achieves high power output without the need for external power input. By utilizing asymmetry, stagger array, magnetic coupling, and nonlinearity strategies, the device maintains a stable output voltage and high power density output at non-resonant frequencies. Temperature and humidity monitoring are performed using Bluetooth sensors to adaptively assess the device.
Article
Energy & Fuels
Tianshu Dong, Xiudong Duan, Yuanyuan Huang, Danji Huang, Yingdong Luo, Ziyu Liu, Xiaomeng Ai, Jiakun Fang, Chaolong Song
Summary: Electrochemical water splitting is crucial for hydrogen production, and improving the hydrogen separation rate from the electrode is essential for enhancing water electrolyzer performance. However, issues such as air bubble adhesion to the electrode plate hinder the process. Therefore, a methodology to investigate the two-phase flow within the electrolyzer is in high demand. This study proposes using a microfluidic system as a simulator for the electrolyzer and optimizing the two-phase flow by manipulating the micro-structure of the flow.
Article
Energy & Fuels
Shuo Han, Yifan Yuan, Mengjiao He, Ziwen Zhao, Beibei Xu, Diyi Chen, Jakub Jurasz
Summary: Giving full play to the flexibility of hydropower and integrating more variable renewable energy is of great significance for accelerating the transformation of China's power energy system. This study proposes a novel day-ahead scheduling model that considers the flexibility limited by irregular vibration zones (VZs) and the probability of flexibility shortage in a hydropower-variable renewable energy hybrid generation system. The model is applied to a real hydropower station and effectively improves the flexibility supply capacity of hydropower, especially during heavy load demand in flood season.
Article
Energy & Fuels
Zhen Wang, Kangqi Fan, Shizhong Zhao, Shuxin Wu, Xuan Zhang, Kangjia Zhai, Zhiqi Li, Hua He
Summary: This study developed a high-performance rotary energy harvester (AI-REH) inspired by archery, which efficiently accumulates and releases ultralow-frequency vibration energy. By utilizing a magnetic coupling strategy and an accumulator spring, the AI-REH achieves significantly accelerated rotor speeds and enhanced electric outputs.
Article
Energy & Fuels
Yi Yang, Qianyi Xing, Kang Wang, Caihong Li, Jianzhou Wang, Xiaojia Huang
Summary: In this study, a novel hybrid Quantile Regression (QR) model is proposed for Probabilistic Load Forecasting (PLF). The model integrates causal dilated convolution, residual connection, and Bidirectional Long Short-Term Memory (BiLSTM) for multi-scale feature extraction. In addition, a Combined Probabilistic Load Forecasting System (CPLFS) is proposed to overcome the inherent flaws of relying on a single model. Simulation results show that the hybrid QR outperforms traditional models and CPLFS exceeds the best benchmarks in terms of prediction accuracy and stability.
Article
Energy & Fuels
Wen-Jiang Zou, Young-Bae Kim, Seunghun Jung
Summary: This paper proposes a dynamic prediction model for capacity fade in vanadium redox flow batteries (VRFBs). The model accurately predicts changes in electrolyte volume and capacity fade, enhancing the competitiveness of VRFBs in energy storage applications.
Article
Energy & Fuels
Yuechao Ma, Shengtie Wang, Guangchen Liu, Guizhen Tian, Jianwei Zhang, Ruiming Liu
Summary: This paper focuses on the balance of state of charge (SOC) among multiple battery energy storage units (MBESUs) and bus voltage balance in an islanded bipolar DC microgrid. A SOC automatic balancing strategy is proposed considering the energy flow relationship and utilizing the adaptive virtual resistance algorithm. The simulation results demonstrate the effectiveness of the proposed strategy in achieving SOC balancing and decreasing bus voltage unbalance.
Article
Energy & Fuels
Raad Z. Homod, Basil Sh. Munahi, Hayder Ibrahim Mohammed, Musatafa Abbas Abbood Albadr, Aissa Abderrahmane, Jasim M. Mahdi, Mohamed Bechir Ben Hamida, Bilal Naji Alhasnawi, A. S. Albahri, Hussein Togun, Umar F. Alqsair, Zaher Mundher Yaseen
Summary: In this study, the control problem of the multiple-boiler system (MBS) is formulated as a dynamic Markov decision process and a deep clustering reinforcement learning approach is applied to obtain the optimal control policy. The proposed strategy, based on bang-bang action, shows superior response and achieves more than 32% energy saving compared to conventional fixed parameter controllers under dynamic indoor/outdoor actual conditions.
