A Study on the Numerical Analysis Methodology for Thermal and Flow Characteristics of High Pressure Turbine in Aircraft Gas Turbine Engine

2020

Mathematics

The flow and heat-transfer attributes of gas turbines significantly affect the output power and overall efficiency of combined-cycle power plants. However, the high-temperature and high-pressure environment can damage the turbine blade surface, potentially resulting in failure of the power plant. Because of the elevated cost of replacing turbine blades, damaged blades are usually repaired through modification of their profile around the damage location. This study compared the effects of modifying various damage locations along the leading edge of a rotor blade on the performance of the gas turbine. We simulated five rotor blades—an undamaged blade (reference) and blades damaged on the pressure and suction sides at the top and middle. The Reynolds-averaged Navier–Stokes equation was used to investigate the compressible flow in a GE-E3 gas turbine. The results showed that the temperatures of the blade and vane surfaces with damages at the middle increased by about 0.8% and 1.2%, respectively. This causes a sudden increase in the heat transfer and thermal stress on the blade and vane surfaces, especially around the damage location. Compared with the reference case, modifications to the top-damaged blades produced a slight increase in efficiency about 2.6%, while those to the middle-damaged blades reduced the efficiency by approximately 2.2%.

Section: Governing Equations and Turbulence Modelsupporting

confidence: 54%

Effects of Leading-Edge Modification in Damaged Rotor Blades on Aerodynamic Characteristics of High-Pressure Gas Turbine

Dam

2020

Mathematics

“…To replace such high-cost models, a Reynolds-average Navier-Stokes (RANS) model ( − ε, − , SST, SST etc. …) is used in turbomachinery simulation and especially, SST and SST − transition models can predict more accurate transitional flows [22,23]. To determine the turbulence model for this study, a steady state analysis was performed.…”

Section: Validation Of the Turbulence Modelmentioning

confidence: 99%

“…The k − ω SST γ turbulence model shows a similar tendency with regard to the experiment values overall, including the SS transition regions. Therefore the k − ω SST γ turbulence model was used in this study with the onset Reynolds number of 150 [23]. In Equation (6), is the heat flux in the isothermal wall simulation, is the wall temperature value in the adiabatic wall simulation, is the blade temperature value for the isothermal case, and ℎ is the HTC.…”

Section: Validation Of the Turbulence Modelmentioning

confidence: 99%

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Numerical Study of the Axial Gap and Hot Streak Effects on Thermal and Flow Characteristics in Two-Stage High Pressure Gas Turbine

Choi

2018

Energies

Combined cycle power plants (CCPPs) are becoming more important as the global demand for electrical power increases. The power and efficiency of CCPPs are directly affected by the performance and thermal efficiency of the gas turbines. This study is the first unsteady numerical study that comprehensively considers axial gap (AG) in the first-stage stator and first-stage rotor (R1) and hot streaks in the combustor outlet throughout an entire two-stage turbine, as these factors affect the aerodynamic performance of the turbine. To resolve the three-dimensional unsteady-state compressible flow, an unsteady Reynolds-averaged Navier-Stokes (RANS) equation was used to calculate a k − ω SST γ turbulence model. The AG distance d was set as 80% (case 1) and 120% (case 3) for the design value case 2 (13 mm or d/Cs 1 = 0.307) in a GE-E 3 gas turbine model. Changes in the AG affect the overall flow field characteristics and efficiency. If AG decreases, the time-averaged maximum temperature and pressure of R1 exhibit differences of approximately 3 K and 400 Pa, respectively. In addition, the low-temperature zone around the hub and tip regions of R1 and second-stage rotor (R2) on the suction side becomes smaller owing to a secondary flow and the area-averaged surface temperature increases. The area-averaged heat flux of the blade surface increases by a maximum of 10.6% at the second-stage stator and 2.8% at R2 as the AG decreases. The total-to-total efficiencies of the overall turbine increase by 0.306% and 0.295% when the AG decreases.

“…Therefore, it is usually considered the method of choice for performing low-cost steady and unsteady CFD simulations. Furthermore, prior investigations [31][32][33] have revealed that the SST γ and SST γ − θ models are the most appropriate for predicting transitional flows. Moreover, the numerical results in [11] obtained using the k − ω SST γ turbulence model demonstrate good agreement with the experimental results reported in [34].…”

Section: Governing Equations and Turbulence Modelmentioning

confidence: 99%

Effects of Damaged Rotor Blades on the Aerodynamic Behavior and Heat-Transfer Characteristics of High-Pressure Gas Turbines

Dam

2021

Mathematics

Gas turbines are critical components of combined-cycle power plants because they influence the power output and overall efficiency. However, gas-turbine blades are susceptible to damage when operated under high-pressure, high-temperature conditions. This reduces gas-turbine performance and increases the probability of power-plant failure. This study compares the effects of rotor-blade damage at different locations on their aerodynamic behavior and heat-transfer properties. To this end, we considered five cases: a reference case involving a normal rotor blade and one case each of damage occurring on the pressure and suction sides of the blades’ near-tip and midspan sections. We used the Reynolds-averaged Navier-Stokes equation coupled with the k − ω SST γ turbulence model to solve the problem of high-speed, high-pressure compressible flow through the GE-E3 gas-turbine model. The results reveal that the rotor-blade damage increases the heat-transfer coefficients of the blade and vane surfaces by approximately 1% and 0.5%, respectively. This, in turn, increases their thermal stresses, especially near the rotor-blade tip and around damaged locations. The four damaged-blade cases reveal an increase in the aerodynamic force acting on the blade/vane surfaces. This increases the mechanical stress on and reduces the fatigue life of the blade/vane components.