Article
Engineering, Aerospace
Wengang Chen, Chuanqiang Gao, Weiwei Zhang, Yiming Gong
Summary: The traditional aerodynamic shape optimization focuses on improving the lift-drag ratio in steady state, while this study improves the onset of transonic buffet through unsteady aerodynamic shape optimization. The variance of lift coefficient in a period is adopted as the optimization objective, and the gradients of the objective function with respect to shape parameters are efficiently calculated using the unsteady discrete adjoint method. The proposed method is verified through two optimization examples, showing increased onsets of transonic buffet and improved aerodynamic performance. The influence of airfoil geometric characteristics on flow stability has been studied.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Gang Yang, Xi Shen, Lei Shi, Jia Meng, Wenhua Luo, Desheng Zhang, B. P. M. (Bart) van Esch
Summary: In this paper, unsteady simulations are conducted to investigate the effects of guide vane openings on the hydrodynamic characteristics of the pump-turbine under stall conditions. The results show that the guide vane openings have a significant influence on the flow pattern, energy loss, pressure fluctuation and radial force. Increasing guide vane openings can exacerbate deep stall, energy loss, pressure fluctuations and radial forces.
ENERGY CONVERSION AND MANAGEMENT
(2023)
Article
Engineering, Aerospace
Gi-Mun Kim, Jin-Young Jeong, Young-Jun Kang, Jae-Su Kwak
Summary: In this study, the aerodynamic loss of gas turbine vane with different trailing edge configurations was experimentally compared. Three cooling schemes (cutback slot, central injection slot, and pressure side hole) and three levels of trailing edge diameter were considered. The results showed that the distribution of total pressure loss was strongly influenced by cooling schemes. The total pressure loss increased as the trailing edge diameter increased, regardless of the cooling schemes.
Article
Thermodynamics
Spencer Owen, Farzad Taremi, Mesbah Uddin
Summary: A computational fluid dynamic investigation was conducted to study the effect of vortex shedding on the trailing edge shock system of an airfoil under different loading conditions. Four modeling strategies were employed, and it was found that the transient modeling approaches had insignificant influence on various parameters except for critical loading. The URANS model failed to predict the transition from near trailing edge dominated vortex formation to base pressure vortex formation, resulting in a significant increase in predicted total pressure loss. The prediction of vortex shape, size, and shock influence varied greatly among the different modeling strategies.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY
(2023)
Article
Thermodynamics
Zakaria Mansouri
Summary: This study evaluated the impact of different forms of hot-streaks on the aerothermal performance of high pressure turbines using numerical simulations. The results showed that the interaction between secondary flows and hot-streaks significantly affected the rotor exit temperature, while the rotor surfaces were influenced by various complex secondary flows.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Timothy A. A. Burdett, Izhar Ullah, Lesley M. M. Wright, Je-Chin Han, John W. W. McClintic, Daniel C. C. Crites, Ardeshir Riahi
Summary: Adiabatic film cooling effectiveness on the endwall of a turbine vane under transonic flow conditions was measured using binary pressure-sensitive paint. The study found that increasing the mass flow ratio, density ratio, and Mach number can improve the film cooling effectiveness.
JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER
(2023)
Article
Energy & Fuels
Shinyoung Jeon, Changmin Son, Jinuk Kim
Summary: The study investigates the effect of swirl clocking on three-dimensional nozzle guide vanes (NGV) using computational fluid dynamics, focusing on the loss characteristics of leaned and swept NGVs, and the impact of swirl clocking. Results demonstrate a redistribution of loading and flow angle under different lean and sweep angles, highlighting the significant influence of three-dimensional design on aerodynamic performance. In the presence of swirl clocking, NGV performance changes significantly, providing new insights and opportunities for improving three-dimensional NGV airfoil design.
Article
Engineering, Aerospace
Yaoyang Li, Hualiang Zhang, Zhao Yin, Jiahui Wang, Haisheng Chen
Summary: This paper presents a numerical study of unsteady flow in the unscalloped radial turbine cavity, finding that under certain sealing flow rates, unsteady low-pressure structures exist and their number and speed decrease as the sealing flow rate increases.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Yuwen Wu, Chunsheng Weng, Quan Zheng, Wanli Wei, Qiaodong Bai
Summary: This study investigates the propagation characteristics of continuous rotating detonation waves with a turbine guide vane and their impact on pressure. Experimental results show that the turbine blade can influence the direction of detonation wave propagation, thereby affecting pressure fluctuations.
Article
Thermodynamics
Wen-li Zhou, Jian Pu, Jian-hua Wang, Hang Su, Yun Chen
Summary: This study experimentally investigated the effect of hole geometry on the unsteady characteristics of film cooling at the leading edge of a turbine vane. Infrared thermography and planar quantitative light sheet techniques were used to analyze the unsteadiness of surface film effectiveness and in-plane jet concentration. The results showed that the flow unsteadiness at the interface of mainstream and cooling air jet is the main cause of surface film effectiveness fluctuation. The fan-shaped hole and the design with a transverse trench displayed better film coverage and effectiveness improvement under different blowing ratios. However, the transverse trench design had lower cooling unsteadiness but challenges in terms of effectiveness decay rate and sidewall cooling unsteadiness.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Green & Sustainable Science & Technology
Jie Lu, Zhongdong Qian, Young-Ho Lee
Summary: The runaway condition in pump turbines exhibits unsteady pressure fluctuations, and the motion and transmission of vortices play a significant role in affecting the internal flow characteristics and characteristic frequencies of the pump turbine.
Article
Chemistry, Multidisciplinary
Cheng Zhu, Weilin Zhuge, Yangjun Zhang
Summary: This paper analyzes the flow characteristics and develops a shock wave-induced loss model for transonic turbines in order to predict their performance more accurately. Experimental results show that the predicted efficiency deviation decreases to a maximum of 3.5% using this model.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Mechanical
Bo Bai, Zhigang Li, Kaiyuan Zhang, Jun Li, Shuo Mao, Wing F. Ng
Summary: The partial blockage of film cooling holes by thermal-barrier coating (TBC) during the spraying process has a significant impact on film cooling performance. A physical model was used to analyze the effects of hole blockage on endwall film cooling performance and overall cooling performance. Results showed that blockage significantly decreases endwall film cooling effectiveness, while its effects on phantom cooling effectiveness are negligible. Hence, large blockage ratios and positions near the holes exit should be avoided during the spraying process.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2023)
Article
Engineering, Mechanical
Mingyang Hao, Bo Bai, Yuanyuan Li, Zhigang Li, Jun Li
Summary: This paper investigates the impact of upstream endwall misalignment on the performance of endwall film cooling and vane surface phantom cooling. Results show that the design geometry with a forward step has a more robust film cooling performance, while the design geometry with a backward step induces reductions in film cooling effectiveness and amplifies performance fluctuations.
JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Mechanical
Zhigang Li, Bo Bai, Jun Li, Shuo Mao, Wing F. Ng, Hongzhou Xu, Michael Fox
Summary: This paper presents experimental and numerical studies on the evaluation of endwall film cooling effectiveness. The results indicate that, at appropriate blowing ratios, injecting coolant through discrete holes can effectively suppress the influence of secondary flows and improve the cooling performance.
JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME
(2022)