Progress & News
Jan 10, 2022
Assembly of the labyrinth seal flutter rig at Imperial College completed
A milestone has been achieved in December 2021 for the manufacture and assembly of the ARIAS ‘Seal Flutter rig’, which has been built at Imperial College Vibration University Technology Centre. The detailed design of this rig was conducted in partnership with Rolls-Royce, MTU Aero engines and ITP, and described in a previous news update on the 16th of July 2020.
The sections of the Seal-Flutter rig were manufactured in Spain, by DOILAN TEGIA S. COOP in late 2020, following a supplier selection process which identified DOILAN as competitive on both price and lead time. All hardware was delivered with a certificate of conformity.
While the rig design is modular and symmetric, the assembly process requires a set of specific steps to be followed in a specific order to bring all the constituent
parts together successfully. The test section was instrumented first as it holds most of the instrumentation and is the reference for all the other sections during build. It is positioned exactly in the middle of the rig.
A modular support frame was built in parallel to the instrumentation of the test section. The frame is designed to withstand the total 1.2 tonnes weight of the rig. The rig is housed in a sound isolation chamber; as a precaution against high volume acoustic responses generated by the rig.
The control valve and actuators require a complex algorithm for safe operation. The PLC box is responsible for the start-up check, shutdown, reset and emergency stop of the rig. Control boxes, DAQ box and power supplies, were installed inside the chamber; while control of the rig happens outside the isolation chamber. The air supply consists of a complex network of pipes, ball-valves, actuated valves, pressure regulators, pressure transmitters and a pneumatic control valve. The compressed air originates from a delivery system within Imperial College’s facilities, but outside the laboratory itself.
A flow calibration plate and the first of the seal specimens for the flutter characterisation test campaign have been received, checked and modal tested. Commissioning testing is expected to be completed in the first quarter of 2022, with flutter test experiments on the baseline seal design planned to start during March.
Dec 17, 2021
Aerodynamic damping measurements at ITSM
The Institute of Thermal Turbomachinery and Machinery Laboratory (ITSM) at the University of Stuttgart is providing new experimental insight into the aerodynamic damping of a compressor blisk to the ARIAS partners. For this purpose, a unique test facility is used that allows operating the compressor blisk at variable inlet pressure levels while exciting the blades in controlled manner at the blade tips. By doing so, the ratio of aerodynamic damping to mechanical damping is varied, which allows extracting the aerodynamic damping from total damping measurements. The total damping in turn is determined from blade vibration measurements using Blade Tip Timing (BTT) technology.
The photo shows the compressor blisk viewed from upstream as well as the excitation system. Great care has been spent in the design of the excitation system to avoid any influence on the flow field. The excitation acts magnetically through the casing wall and may be toggled in controlled manner.
Dec 6, 2021
Experimental campaigns in WP2 successfully completed!
Typically, flutter and forced response are the two main sources of vibration in turbines and are responsible for most of the potential High Cycle Fatigue issues in the modules. Current prediction and analysis methodologies are adequate when either of them is present in a turbine, but they are not really prepared to deal with the interaction between both phenomena when both appear simultaneously. In WP2 of the ARIAS project two extensive experimental campaigns, utilizing Avio's spin rig facility and CTA's cold flow facility, were carried out with a goal to characterize empirically the interaction between flutter and forced response. To that end, an existing test article (from the FP7 FUTURE project) was modified, including accessories like dampers, mistuning masses, fixing devices or magnet frames.
Both measurement campaigns have now been completed successfully, providing high quality blade tip timing (BTT) data and unsteady pressure data. The post-processing and analysis of the test data is ongoing and the development and validation of related simulation methods will be the focus for the remaining period in the project.
Nov 26, 2021
Continued Collaboration through Aeromechanics Project Course
The collaborative international student project course that started off in 2019 as an initiative for bringing closer ARIAS research efforts to the education, will be run for the 3rd year in a row during the spring 2022. This time we will have around 25 students from TU Darmstadt, KTH and UPM organized in multinational teams working together on a research question related to the parameters influencing forced response in transonic compressors. Beside the project work, during the course the students will receive a rather comprehensive training in turbomachinery aeromechanics consisting of lectures, turorials and guest lectures from the specialists coming both from industry and academia. At the end of the course the students will also have an opportunity to present their findings for the ARIAS partners. This is indeed a great learning experience for all students involved!
Aug 17, 2020
Successful Commissioning of the ARiAS Transonic Compressor at TU Darmstadt
As part of the extensive experimental investigations within the ARiAS project, the transonic compressor test setup was successfully commissioned at the TU Darmstadt Transonic Compressor Rig.
The compressor stage was enhanced with new rig hardware and equipped with extensive steady and unsteady instrumentation, in order to tackle the upcoming aerodynamic and aeromechanical tests. Focusing on forced response phenomena and the underlying fluid-structure-interaction due to blade and vane row interaction, a new developed wake generator module is applied upstream the rotor BLISK. One goal of the first out of two measurement campaigns is to experimentally characterize the flow features and determine the impact of wake forcing and rotor tip-clearance on blade vibration excitation and aero-damping by performing a parameter study of varying inlet wake types and counts. Ultimately, the experimental results will be used to identify and explain the physical mechanisms fundamental to these interactions and their impact on aeromechanical vibrations, necessary to enhance and validate the numerical tools of industry and academia.environment.
July 16, 2020
Design and construction of a modular and novel static seal rig facility
Labyrinth seals are components used throughout the gas turbine to minimise air leakage between rotating and stationary components from high to low pressure regions. The rotating element of the seal is generally flexible and due to its interaction with the seal flow, flutter can occur which can cause unexpected failure of the labyrinth seal and consequently significant damage to the engine.
Work package 3 in ARIAS aims to address limitations in the current understanding, of the physics of flutter in labyrinth seals. An experimental rig has been designed in partnership with: Imperial College London, ITP-Aero, MTU Aero-Engines, Rolls-Royce plc and Universidad Politécnica de Madrid. The intent of this innovative static test facility is to provide high quality data to study the physics of seal flutter and provide validation data for analytical and numerical approaches. The test rig allows a wide range of flow and dynamic parameters to be tested , to identify and quantify the influence of different seal designs and flow conditions on the occurrence of seal flutter. The rig experiments will be modelled analytically to enable direct comparison with measurements from both, aerodynamic and structural instrumentation, something that is extremely costly and difficult to achieve in a real engine environment.
Design and commission a novel seal flutter test facility.
Provide a consistent and complete physical account of the flutter phenomena of labyrinth seals. Assess individual influencing parameters for seal flutter and their interdependencies.
Generate a unique experimental data base of key results for a number of seal design configurations and operating points, under carefully controlled conditions.
Validate analytical methods, ranging from high-resolution aero-mechanical simulations to lower-fidelity parameter based approximations.
Key Features of the rig:
Non-Rotating Design: This eliminates the inherent complexity and cost of design, instrumentation and operation in a rotating rig. The behavioural differences between rotating and static test articles are overcome through careful design of the rig, the test articles and the use of piezo-electric actuators.
Modular construction : This novel design approach allows the cavity sections and the test specimens to be easily and rapidly replaced, modified and instrumented to simulate a wide range of configurations.
Symmetric Design : The symmetric design allows a high degree of flexibility with respect to the seal-flow configuration and the seal support arrangement.
Conical test section : Allows various seal-tip gap clearances to be tested.
Advanced Instrumentation: A wide ranging suite of instrumentation to measure steady and unsteady flows; steady deflections and dynamic behaviour of the test specimens.
Multifarious Test Specimens: The experimental test facility will allow the study of seal behaviour for a variety of seal geometries under conditions of flutter. The test section can accommodate seals with 1 to 4 fins.
Tuneable Plenum Cavities: Radial and axial modular inserts allow control of the acoustic resonance frequencies within the rig’s plenum cavities.
Feb 1, 2020
Collaborative student projects within frame of ARIAS project
One of the goals of the ARIAS project is to bring the current research in aeromechanics closer to the education. To achieve that several collaborative educational activities will be carried out among the academic partners in the project. One example of such initiative is a student project course that started off in January this year and which is carried out by the students from KTH and TU Darmstadt, The course focuses on an aeroelasticity study in aero engines using interdisciplinary tools to investigate structural and aerodynamic effects. It includes introductory lectures on the aeromechanical phenomenon investigated, tool specific tutorials as well as guest lectures by the specialists involved in the ARIAS project, but also from outside of the consortium . The students work via web-based communication in multi-national teams conducting various simulations to determine distinct influences on forced response phenomena at the TU Darmstadt transonic compressor test facility. It will be really interesting to see at the end how well the numerical results obtained by the student teams compare to the experimental result which will come out of the measurement campaigns in WP1 of the ARIAS project!
October 1-3, 2019
3rd ARIAS consortium meeting at Ecole Centrale de Lyon
The third consortium meeting took place at ECL on 1-3 of October 2019. During this three-day meeting the partners had opportunity to discuss details of the ongoing work and planned measurement campaigns. The design work related to the several test rigs in the project is approaching it's final phase and the procurement and manufacturing of the different rig parts and test objects has been initialized. An External Advisory Board (EAB) consisting of three renowned experts in the field of aeromechanics was also invited to participate in the meeting with the main task of reviewing the experimental plans for the work packages. The EAB members were in general pleased with the progress of the project and they provided a valuable input to the partners that will carry out the experiments. The meeting was wrapped up with a guided tour of LTDS - Laboratory of Tribology and Systems Dynamics and LMFA - Laboratory of Fluid Transfer and Acoustics at Ecole Centrale. Very impressive facilities indeed!
June 3-4, 2019
Blade Tip Timing Workshop at TU Darmstad
Hosted by the Institute of Gas Turbines and Aerospace Propulsion at TU Darmstadt, the European tip timing community within ARiAS met for a “Blade Tip Timing Workshop”. Tip timing experts of Rolls Royce, Siemens AG, MTU Aero Engines, SAFRAN Aircraft Engines/ Helicopter Engines/ Aero Booster and GKN Aerospace as well as testing and measurement experts of TU Darmstadt and University of Stuttgart joined the meeting on 3rd and 4th of June 2019. Several presentations and discussions enabled the exchange and a common understanding of the different tip timing systems as well as the corresponding capabilities and differences. Furthermore, the ARiAS test facilities and related tip timing measurements have been presented, including a visit of the compressor and turbine test rigs at TU Darmstadt, in order to provide an overview of the upcoming test campaigns and challenges. The attending partners agreed on an ARiAS standard format for tip timing data exchange, enabling a collaborative data acquisition at the various test facilities and analysis with the different systems and tools. For benchmarking of the current state of analysis tools and methods, a set of test cases will be introduced
October 25 , 2018
WP3 Static seal flutter rig design workshop
On Thursday the 25th October the industrial partners of WP3 (RR, MTU, ITP) met at Imperial College London in order to define the requirements for the ARIAS static seal flutter rig. The workshop was facilitated by a design requirements-capture specialist and enabled the partners to define and document the desired functional and physical attributes of the rig. A well-defined set of requirements is a key first step in the design process, ensuring that the end product will deliver the novel and highly valuable experimental measurements and behaviour observations that will advance our understanding of seal aeroelasticity.
March 12-13, 2019
2nd ARIAS consortium meeting at Safran Aircraft Engines
The second consortium meeting took place at SAFRAN Aircraft Engines site in Villaroche France on 12 & 13 of March 2019. A two-day meeting was a great opportunity to meet and discuss the ongoing design work for the several of the large measurement campaigns that we will soon start within the project. The meeting was wrapped up with a guided tour of impressive assembly lines for the LEAP engine!
September 15 , 2018
ARIAS project was successfully launched by a consortium meeting held at KTH Royal Institute of Technology in Stockholm on 13th & 14th of September 2018. Over 35 participants, all eager to begin with the project work, met together to set up a solid foundation for an outstanding project. The meeting was also attended by H2020 project officer Hugues Felix from the Innovation and Networks Executive Agency (INEA) , who shed a light on European Commission's latest rules and procedures concerning H2020 projects.