Delayed Detached Eddy Simulation of a Full 3-Dimensional High-Pressure Turbine Stage: Part I — Flow Topology

2018 ◽  
Author(s):  
Dun Lin ◽  
Xiutao Bian ◽  
Xin Yuan ◽  
Xinrong Su
Keyword(s):  
High Pressure ◽  
Horseshoe Vortex ◽  
Wake Vortex ◽  
High Fidelity ◽  
Detached Eddy Simulation ◽  
Tip Leakage Flow ◽  
High Pressure Turbine ◽  
Flow Topology ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

In this work, the flow inside a high pressure turbine (HPT) stage is studied with the help of a high-fidelity delayed detached eddy simulation (DDES) code. This work intends to study the flow topology in the HPT stage. There are two motivations for this work: On the one hand, high pressure turbines operates at both transonic Mach numbers and high Reynolds numbers, which imposes a challenge to modern computational fluid dynamics (CFD), especially for scale-resolved simulation methods. An accurate and efficient high-fidelity CFD solver is very important for a thorough understanding of the flow physics and the design of higher-efficient HPT. On the other hand, the wake vortex shedding and tip-leakage flow are important origins of turbine losses and unsteadiness. Built on our previous DDES simulations of HPT vane and stage, this work further investigates the flow in a full 3-dimension HPT stage. The flow topology in the HPT stage is delineated by Q-criterion iso-surfaces. The development of the horseshoe vortex and its interaction with induced vortex and wake vortex is discussed. The wake vortex transportation especially its interaction with the rotor horseshoe vortex is investigated. The flow structures in the tip clearance region are also revealed.

DDES Analysis of Wake Vortex Related Unsteadiness and Losses in the Environment of High-Pressure Turbine Stage

2017 ◽  
Author(s):  
Dun Lin ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
High Pressure ◽  
Boundary Layer Transition ◽  
Wake Vortex ◽  
High Fidelity ◽  
Strong Impact ◽  
Detached Eddy Simulation ◽  
High Pressure Turbine ◽  
Layer Transition ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

In this work, the flows inside the high pressure turbine (HPT) vane and stage are studied with the help of a high-fidelity delayed detached eddy simulation (DDES) code. This work intends to study the fundamental nozzle/blade interaction with special attention paid to the development and transportation of the vane wake vortex. There are two motivations for this work. On the one hand, the high pressure turbine operates at both transonic Mach numbers and high Reynolds numbers, which imposes a great challenge to modern computational fluid dynamics (CFD), especially for scale-resolved simulation methods. An accurate and efficient high-fidelity CFD solver is very important for a thorough understanding of the flow physics and the design of more efficient HPT. On the other hand, the periodic wake vortex shedding is an important origin of turbine losses and unsteadiness. The wake and vortex not only cause losses themselves, but also interact with the shock wave (under transonic working condition), pressure waves, and have a strong impact on the downstream blade surface (affecting boundary layer transition and heat transfer). Built on one of our previous DDES simulations of a HPT vane VKI LS89, this work further investigates the development and length characteristics of the wake vortex, provides explanations of the length characteristics and reveals the transportation of the wake vortex into the downstream rotor passage along with its impact on the downstream aero-thermal performance.

DDES Analysis of the Wake Vortex Related Unsteadiness and Losses in the Environment of a High-Pressure Turbine Stage

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Dun Lin ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
High Pressure ◽  
Boundary Layer Transition ◽  
Wake Vortex ◽  
Strong Impact ◽  
Detached Eddy Simulation ◽  
High Pressure Turbine ◽  
Layer Transition ◽  
Wake Vortices ◽  
Operation Conditions ◽  
Delayed Detached Eddy Simulation

In this work, the flows inside a high-pressure turbine (HPT) vane and stage are studied with a delayed detached eddy simulation (DDES) code. The fundamental nozzle/blade interaction is investigated with special attention paid to the development and transportation of the vane wake vortices. There are two motivations for this work. First, the extreme HPT operation conditions, including both transonic Mach numbers and high Reynolds numbers, impose a great challenge to modern computational fluid dynamics (CFD), especially for scale-resolved simulation methods. An accurate and efficient high-fidelity CFD solver is very important for a thorough understanding of the flow physics and the design of more efficient HPT. Second, the periodic wake vortex shedding is an important origin of turbine losses and unsteadiness. The wake and vortices not only cause losses themselves, but also interact with the shock wave (under transonic working condition), pressure waves, and have a strong impact on the downstream blade surface (affecting boundary layer transition and heat transfer). Based on one of our previous DDES simulations of a HPT vane, this work further investigates the development and length characteristics of the wake vortices, provides explanations for the length characteristics, and reveals the transportation of the wake vortices in the downstream rotor passages along with its impact on the downstream aero-thermal performance.

scholarly journals Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 21 ◽  
Author(s):  
Hui Li ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Tip Clearance ◽  
Flow Structures ◽  
Leakage Flow ◽  
Detached Eddy Simulation ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Passage Vortex ◽  
Unsteady Effects

In unshrouded turbine rotors, the tip leakage vortices develop and interact with the passage vortices. Such complex leakage flow causes the major loss in the turbine stage. Due to the complex turbulence characteristics of the tip leakage flow, the widely used Reynolds Averaged Navier–Stokes (RANS) approach may fail to accurately predict the multi-scale turbulent flow and the related loss. In order to effectively improve the turbine efficiency, more insights into the loss mechanism are required. In this work, a Delayed Detached Eddy Simulation (DDES) study is conducted to simulate the flow inside a high pressure turbine blade, with emphasis on the tip region. DDES results are in good agreement with the experiment, and the comparison with RANS results verifies the advantages of DDES in resolving detailed flow structures of leakage flow, and also in capturing the complex turbulence characteristics. The snapshot Proper Orthogonal Decomposition (POD) method is used to extract the dominant flow features. The flow structures and the distribution of turbulent kinetic energy reveal the development of leakage flow and its interaction with the secondary flow. Meanwhile, it is found that the separation bubble (SB) is formed in tip clearance. The strong interactions between tip leakage vortex (TLV) and the up passage vortex (UPV) are the main source of unsteady effects which significantly enhance the turbulence intensity. Based on the DDES results, loss analysis of tip leakage flow is conducted based on entropy generation rates. It is found that the viscous dissipation loss is much stronger than heat transfer loss. The largest local loss occurs in the tip clearance, and the interaction between the leakage vortex and up passage vortex promotes the loss generation. The tip leakage flow vortex weakens the strength of up passage vortex, and loss of up passage flow is reduced. Comparing steady and unsteady effects to flow field, we found that unsteady effects of tip leakage flow have a large influence on flow loss distribution which cannot be ignored. To sum up, the current DDES study about the tip leakage flow provides helpful information about the loss generation mechanism and may guide the design of low-loss blade tip.

High-fidelity fan-noise simulations based on improved delayed detached eddy simulation

2021 ◽  
Vol 150 (4) ◽  
pp. A131-A131
Author(s):  
Takao Suzuki ◽  
Michael L. Shur ◽  
Michael K. Strelets ◽  
Andrey K. Travin ◽  
Philippe R. Spalart
Keyword(s):  
High Fidelity ◽  
Detached Eddy Simulation ◽  
Fan Noise ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

Flow Mechanism and Loss Analysis of Tip Leakage Flow With Delayed Detached Eddy Simulation

2019 ◽  
Author(s):  
Hui Li ◽  
Xiutao Bian ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Entropy Generation ◽  
Flow Structures ◽  
Leakage Flow ◽  
Detached Eddy Simulation ◽  
Tip Leakage Flow ◽  
Turbulence Characteristics ◽  
Tip Leakage ◽  
Loss Analysis ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

Abstract The complex leakage flow structure in the tip region of unshrouded rotor is a main source of turbine aerodynamic loss. Due to the complex turbulence characteristics of the tip leakage flow, the widely used Reynolds Averaged Navier-Stokes (RANS) approach may fail to accurately predict the multi-scale turbulent flow and the related loss. In order to effectively improve the turbine efficiency, more insights into the turbulence characteristics and the loss mechanism in the tip leakage flow are required. In this work, a Delayed Detached Eddy Simulation (DDES) study is conducted to simulate the flow inside a high pressure turbine blade, with emphasis on the tip region. DDES results are in good agreement with the experiment and the comparison with RANS results verifies the advantages of DDES in resolving finer flow structures of leakage flow, also in capturing the complex turbulence characteristics. The snapshot Proper Orthogonal Decomposition (POD) method is used to extract the dominant flow features. The flow structures and the distribution of Reynolds stress help to reveal the process of leakage flow and its interaction with the secondary flow. Meanwhile, it is found that the separation vortex (SV) forms from leading edge to trailing edge, and the strong interactions between tip leakage vortex (TLV) and passage secondary vortex (PSV) significantly enhance the turbulence intensity. Based on the DDES results, loss analysis of tip leakage flow is conducted based on entropy generation rates. For the leakage flow related loss, the largest local entropy generation rate occurs at 50 % of axial chord, and the interaction between the leakage vortex and up passage vortex promotes the loss generation. To sum up, the current DDES study about the tip leakage flow provides helpful information about the loss generation mechanism and may guide the design of low-loss blade tip.

Steady State and Transient CFD Studies on Aerodynamic Performance Validation of a High Pressure Turbine

2012 ◽  
Author(s):  
Sridhar Murari ◽  
Sathish Sunnam ◽  
Jong S. Liu
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Aerodynamic Performance ◽  
Detached Eddy Simulation ◽  
High Pressure Turbine ◽  
Predictive Capacity ◽  
Flow Angle ◽  
Analysis And Design ◽  
Eddy Simulation

With the advent of fast computers and availability of less costly memory resources, computational fluid dynamics (CFD) has emerged as a powerful tool for the design and analysis of flow and heat transfer of high pressure turbine stages. CFD gives an insight in to flow patterns that are difficult, expensive or impossible to study using experimental techniques. However, the application of CFD depends on its accuracy and reliability. This requires the CFD code to be validated with laboratory measurements to ensure its predictive capacity. In the continual effort to improve analysis and design techniques, Honeywell has been investigating in the use of CFD to predict the aerodynamic performance of a high pressure turbine. Reynolds Averaged Navier Stokes (RANS), unsteady models like detached eddy simulation (DES), large eddy simulation (LES), and Scale Adaptive Simulation (SAS) are used to predict the aerodynamic performance of a high pressure turbine. Mixing plane approach is used to address the flow data transport across the stationary interface in RANS simulation. The film holes on blade surface and end walls for all the analysis are modeled by using actual film hole modeling technique. The validation is accomplished with the test results of a high pressure turbine, Energy Efficient Engine (E3). The aerodynamic performance data at design point, typical off-design points are taken as test cases for the validation study. One dimensional performance parameters such as corrected mass flow rate, total pressure ratio, cycle efficiency, and two dimensional spanwise distributions of total pressure, total temperature and flow angle that are obtained from CFD results are compared with test data. Streamlines and flow field results at different measurement planes are presented to understand the aerodynamic behavior.

scholarly journals Numerical Investigation of the Wake Vortex-Related Flow Mechanisms in Transonic Turbines

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Guoliang Wang ◽  
Ning Ge ◽  
Dongdong Zhong
Keyword(s):  
High Pressure ◽  
Great Influence ◽  
Flow Characteristics ◽  
Entropy Generation Rate ◽  
Wake Vortex ◽  
High Pressure Turbine ◽  
Local Loss ◽  
Eddy Simulation ◽  
Flow Mechanisms ◽  
Sas Model

As the core equipment of the power generation system, a gas turbine is an indispensable energy-converting device in the national industry. The flow inside a high-pressure turbine (HPT) is highly unsteady, which has a great influence on the aerothermal performance and structural strength. To better clarify the flow mechanism and guide the advanced design, the basic flow characteristics of transonic turbines are investigated in the paper by a modified scale-adaptive simulation (SAS) model based on the shear stress transport (SST) turbulence model. The numerical results reveal the formation and development of the secondary flow structures such as wake vortex, pressure wave, shock wave, and the interactions among them. The length and frequency characteristics of wake are in good agreement with the large eddy simulation (LES) and the experimental data. Based on the detailed flow information, the local loss analysis is performed using the entropy generation rate. In summary, the wake vortex-related flow is the main origin of unsteadiness and entropy loss in high-pressure turbine cascade.

Sign in / Sign up

Export Citation Format

Share Document