Gas Turbine Stator-Well Flow and Heat Transfer.
Lead Research Organisation:
University of Bath
Department Name: Mechanical Engineering
Abstract
Gas turbines are a common form of combustion engine, used to either generate electrical energy or thrust depending on the application. These machines are comprised of a compressor, combustor, and turbine which act to extract energy from high temperature and high-pressure air to generate power. The internals of the turbine region consist of many stages of fixed and rotating blades attached to discs, which are designed to withstand the extreme temperatures and forces applied from the gas that passes through the mainstream. In order to maximise the service life of a gas turbine, the heat transfer to the disc surfaces must be carefully predicted to reduce wear and prevent failure, with overhaul and maintenance costs being a significant cost to the engine supplier. Detailed knowledge of the flow conditions and temperatures within the turbine is therefore vital in making these predictions, helping to identify improvements to the turbine design to extend its operational life.
One aspect of the fluid flow within the turbine is the interactions between the cavities created between the rotating (rotor) and fixed (stator) blade sets, known as "stator wells". These cavities have small clearances, which limits the ability to vent hot air and inject cooling air within these gaps, resulting in high rates of heat transfer to the disc surfaces. The complexity of the fluid dynamics in these regions has limited the level of detail computational methods have been able to resolve, with flow characteristics such as ingestion, re-ingestion, purge and leakage all leading to further questions on the interactions within the cavities.
The aim of this research is to use a coupled conjugate heat transfer (CHT)/computational fluid dynamics (CFD) solver to understand the fundamental fluid dynamics and heat transfer characteristics occurring within the turbine stator wells. This software will be developed to form a theoretical model of the test cases and then solved using the boundaries given from experimental data. Validation will be performed using existing experimental data from the in-house compressor cavity rig before being applied to turbine stator well problem.
One aspect of the fluid flow within the turbine is the interactions between the cavities created between the rotating (rotor) and fixed (stator) blade sets, known as "stator wells". These cavities have small clearances, which limits the ability to vent hot air and inject cooling air within these gaps, resulting in high rates of heat transfer to the disc surfaces. The complexity of the fluid dynamics in these regions has limited the level of detail computational methods have been able to resolve, with flow characteristics such as ingestion, re-ingestion, purge and leakage all leading to further questions on the interactions within the cavities.
The aim of this research is to use a coupled conjugate heat transfer (CHT)/computational fluid dynamics (CFD) solver to understand the fundamental fluid dynamics and heat transfer characteristics occurring within the turbine stator wells. This software will be developed to form a theoretical model of the test cases and then solved using the boundaries given from experimental data. Validation will be performed using existing experimental data from the in-house compressor cavity rig before being applied to turbine stator well problem.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/R511833/1 | 01/10/2017 | 31/12/2022 | |||
| 2440303 | Studentship | EP/R511833/1 | 01/10/2020 | 30/09/2023 | James PARRY |
| Description | A new methodology for resolving temperatures in conjugate problems has been implemented into the opensource simulation software OpenFOAM. To achieve this, a new solver and conjugate boundary condition has been developed using C++ and implemented into OpenFOAM. This new method has been validated using experimental results from the University of Bath's Compressor Cavity rig. The software has demonstrated not only good agreement with the experimental results, but also validated the assumed temperatures in the fluid predicted by theoretical models that are unable to be captured by experiments. The model has demonstrated it is suitable to act as a predictive tool, able to predict results independently from experiments. |
| Exploitation Route | The coding methodology is implemented into the opensource software OpenFOAM, so will be available to anyone looking to use the software. The applications for the code are not solely limited to turbomachinery, but any scenario where heat transfer occurs, particularly those with highly rotational fluid flows. |
| Sectors | Aerospace, Defence and Marine |
| Description | Next generation and future aero-engines will feature core compressors with smaller dimensions and higher overall pressure ratios. This is in order maximise efficiency within the system, requiring high Turbine Entry Temperatures, while making the engine weight as low as possible. Due to the high temperatures experienced in the high-pressure compressors and turbines, the rotating discs in the core can experience radial growth. This can be an issue for the blades attached to these discs, where the radial growth can risk contact with the stationary outer casing and lead to damage to the engine. Understanding the temperature distributions in the discs is vital for engine designers; with accurate predictions of the radial growth dictating the clearance margins needed for maximising efficiency of the engine. The methodology and code developed can be used as a predictive tool for estimating the temperature of both the air in the engine as well as the metal discs, capturing the conjugate heat transfer between the two. This is of interest in industry in the design of these future engines. |
| First Year Of Impact | 2022 |
| Sector | Aerospace, Defence and Marine,Energy |
| Impact Types | Economic |