Abstract:The behaviour of the jet engine during transient operation and specifically its secondary air system (SAS) is the point of this work. This paper presents a methodological approach to develop a fast, one-dimensional transient platform for preliminary analysis of the flow behaviour in gas turbine engines secondary air system. For this purpose, different elements of the system including rotating chamber, pipe, turbine blade cooling, orifice, and labyrinth seal are modelled in a modular form. The validity of the d… Show more
“…Due to the difficulty in accurately computing the temperature reduction and pressure loss in the pre-swirl system using the one-dimensional method, a CFD code is utilized to conduct full three-dimensional flow simulation while the turbine blade cooling adopts the analytical model. 3 The advantage of combining 1D-3D coupling method in the SAS computation is that a balance between computational requirements and efficiency can be achieved.Figure 1.Schematic of CFM56 engine and its SAS. 13 Figure 2.Co-simulation model for the AGTF30 engine and the designed SAS.…”
Section: Model Set Up and Test Definitionmentioning
confidence: 99%
“…A classic SAS can be simulated using a library of five elements: a rotating cavity, a pipe, a labyrinth seal, an orifice, and blade cooling passages. 3 Each flow element represents a section of the flow passage that can be regarded as a closed entity. The coolant air passes through these elements from a compressor bleed point along flow paths that split up or join together at the nodes.…”
This research studies the performance of an ultra-high bypass ratio turbofan engine, and specifically its secondary air system (SAS). A co-simulation methodology is explored whereby a high-fidelity SAS model and an engine performance code featuring flexible modules can be coupled and interactively executed. The percentage of bleed flows and boundary conditions for the SAS are updated at each iteration step. For this purpose, a SAS model including different elements is developed. Furthermore, a commercial computational fluid dynamics (CFD) solver is adopted to capture the complex flow field in the pre-swirl system. The credibility of cycle calculation and SAS elements is validated by comparing with publicly available data. Subsequently, an elaborately designed SAS is modeled and co-simulated with the AGTF30 engine using a flow network simulation method. The coupling effect between the engine performance and the SAS is studied for eight different flight conditions. The correlation and prediction of engine performance due to seal clearance change is presented. The co-simulation approach clarifies the mutual interactions between the engine overall parameters and the SAS. The results reveal that the enhanced flow network model can improve the simulation accuracy of engine performance over a wide range of operating conditions.
“…Due to the difficulty in accurately computing the temperature reduction and pressure loss in the pre-swirl system using the one-dimensional method, a CFD code is utilized to conduct full three-dimensional flow simulation while the turbine blade cooling adopts the analytical model. 3 The advantage of combining 1D-3D coupling method in the SAS computation is that a balance between computational requirements and efficiency can be achieved.Figure 1.Schematic of CFM56 engine and its SAS. 13 Figure 2.Co-simulation model for the AGTF30 engine and the designed SAS.…”
Section: Model Set Up and Test Definitionmentioning
confidence: 99%
“…A classic SAS can be simulated using a library of five elements: a rotating cavity, a pipe, a labyrinth seal, an orifice, and blade cooling passages. 3 Each flow element represents a section of the flow passage that can be regarded as a closed entity. The coolant air passes through these elements from a compressor bleed point along flow paths that split up or join together at the nodes.…”
This research studies the performance of an ultra-high bypass ratio turbofan engine, and specifically its secondary air system (SAS). A co-simulation methodology is explored whereby a high-fidelity SAS model and an engine performance code featuring flexible modules can be coupled and interactively executed. The percentage of bleed flows and boundary conditions for the SAS are updated at each iteration step. For this purpose, a SAS model including different elements is developed. Furthermore, a commercial computational fluid dynamics (CFD) solver is adopted to capture the complex flow field in the pre-swirl system. The credibility of cycle calculation and SAS elements is validated by comparing with publicly available data. Subsequently, an elaborately designed SAS is modeled and co-simulated with the AGTF30 engine using a flow network simulation method. The coupling effect between the engine performance and the SAS is studied for eight different flight conditions. The correlation and prediction of engine performance due to seal clearance change is presented. The co-simulation approach clarifies the mutual interactions between the engine overall parameters and the SAS. The results reveal that the enhanced flow network model can improve the simulation accuracy of engine performance over a wide range of operating conditions.
“…Sangjo [ 35 ] suggested a data-driven modelling approach, considering the time delay included in the measured temperature from a sensor, to create a high prediction accuracy during dynamic operation. Theoklis et al [ 36 ] worked on the gas turbine secondary air system’s transient modelling and simulation. The secondary air system of a two-spool turbofan engine is studied and simulated in transient mode using a flow network modelling approach.…”
The power demand from gas turbines in electrical grids is becoming more dynamic due to the rising demand for power generation from renewable energy sources. Therefore, including the transient data in the fault diagnostic process is important when the steady-state data are limited and if some component faults are more observable in the transient condition than in the steady-state condition. This study analyses the transient behaviour of a three-shaft industrial gas turbine engine in clean and degraded conditions with consideration of the secondary air system and variable inlet guide vane effects. Different gas path faults are simulated to demonstrate how magnified the transient measurement deviations are compared with the steady-state measurement deviations. The results show that some of the key measurement deviations are considerably higher in the transient mode than in the steady state. This confirms the importance of considering transient measurements for early fault detection and more accurate diagnostic solutions.
“…The secondary air system (SAS) plays an important support role to ensure the safe and efficient operation of aeroengines. [1] Increasing demands for high performance, energy-saving, and safety levels for aeroengines are attracting more interest in the accurate analysis and refined design of the secondary air system. Labyrinth, as an important noncontact rotor-stator sealing device, has been widely used in the secondary air system of aeroengines due to its simple structure and high reliability.…”
Straight-through labyrinth seal is a simple and reliable noncontact seal structure widely used in aeroengines. During the actual operation of aeroengines, the labyrinth seal clearance might experience a nonuniform variation in the flow direction due to asymmetric structure and uneven temperature. In order to characterize the degree of nonuniformity, the nonuniformity coefficient is defined in current paper. The effect of nonuniform causes (rotor deformation or stator deformation), nonuniform type (convergent clearance or divergent clearance), and nonuniformity coefficient (nonuniformity degree) is carefully studied by numerical simulation. Comparative analysis has shown that there is no obvious difference in flow coefficient (less than 0.8% in current studies) between two nonuniform causes. As for nonuniform type, the nonuniformity impact of divergent type on the flow coefficient is more significant than that of convergent type, as a result of stronger axial inertia. Pressure distributions of teeth cavities indicate that the total pressure drop of the divergent type is more obvious than that of the convergent type when the pressure ratio is the same. With the same dimensionless minimum tip clearance, clearance nonuniformity would result in the increase of leakage flow of the straight-through labyrinth, particularly for the condition with small pressure ratio, large circumferential Mach number, and small dimensionless minimum tip clearance. When the nonuniformity coefficient is within the range of -0.1 to 0.1, the variation curves of nonuniformity impact factor versus the nonuniformity coefficient almost coincide (the maximum deviation is no more than 1.2%) under different operation conditions (Reynolds number, pressure ratio, circumferential Mach number, and dimensionless minimum tip clearance). Current work proves it that the effect of seal clearance nonuniformity on the leakage flow requires special attention for the refined design of aeroengines.
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