Final Report Summary - DECROR (Structural design of a counter-rotating open rotor)
Executive summary:
The DECROR project consists of the IBK company as sole partner and therefore coordinator. IBK is a small and medium-sized enterprise (SME) located in Germany with a long history as research and technological development (RTD) service provider in the fields of structural mechanics, fluid mechanics and couplings of both domains. With this project IBK was introduced into WP2222 of 'Smart fixed wing aircraft' (SFWA). During the IBK project worked on the 'Design of counter-rotating open rotors' (DECROR). Work combining different disciplines in mechanical engineering was performed, the results were delivered and discussed with the partners. Due to some late input the project itself had to be extended for six months, without an effect on costs.
Project context and objectives:
The DECROR project consists of the company IBK as sole partner and therefore coordinator. IBK is an SME located in Germany with a long history as RTD service provider in the fields of structural mechanics, fluid mechanics and couplings of both domains. With this project IBK was introduced into WP2222 of SFWA.
DECROR tackled the structural design of real-scale as well as wind-tunnel models for a counter-rotating open rotor. The work for this project was structured in two main phases: In the first phase the focus was on wind-tunnel models with different scales and different operating conditions (takeoff, cruise). Using Input from partners (Airbus, NLR, DLR, ONERA) IBK created a structural finite element (FE) model and performed different calculations.
- The testing in a wind tunnel has high-strength requirements therefore it was to be made sure that the blades do not fail.
- It is important that the eigenfrequencies of the blades are not excited during the tests. Therefore, an eigenvalue analysis was performed under operation conditions in order to make sure that the blades can be tested safely.
- For the final manufacturing it was important to calculate a so called 'Cold-Shape', meaning a shape that deforms under operating conditions into the so called 'Hot-Shape' or design-shape, the geometry that was used during the design. Calculating this shape was performed by IBK.
As results of this first phase wind-tunnel models for three different scales were created and delivered to the partners of WP2222 for subsequent analysis.
In the second phase of the project the focus shifted to the real-scale models. Using design-loads delivered from Airbus IBK performed the structural design using different blade-design approaches, optimising skin and spar positions and thicknesses and comparing different solutions with each other. Main driver was saving weight; however, all necessary requirements had to be fulfilled.
- Strength: The blade was not allowed to fail.
- Fatigue: The blade had to endure a certain number of load-cycles.
- Aeroelasticity: No flutter during the operating conditions.
- Impact: Using tyre-impact conditions a simplified calculation was performed showing that after the impact occurred the blade could sustain all damages during the impact.
- Stability: The eigenfrequencies of the blade may not be excited during the blade operation.
As result again FE models were created which were delivered to the partners for subsequent analysis.
As a major outcome for IBK it can be said:
IBK performed all actions necessary for rotor-design in-house. Especially the impact analysis of a carbon-fibre-reinforced polymer (CFRP) structure is a very challenging task and could be performed creating special routines needed for these kinds of calculations. IBK created different software solutions and processes, especially for:
- performing eigenfrequency calculations based on non-linear FE results taking into account centrifugal effects;
- design of CFRP parts using a structural optimiser in a semi-automatic process;
- methods for performing impact-calculations using a conservative approach.
Project results:
Againg, since this is way a very strongly focused projects which was intended to deliver input needed for the work of other partners within the SFWA integrated technology demonstrator' (SFWA-ITD) the results in terms of foregrounds are difficult to assess.
IBK performed a lot of very complex steps during this project:
- Eigenvalue calculations of rotating elements including centrifugal stiffening effects: Although this work is done using standard-software the actual adaption for a CFRP material and a non-linear calculation procedure is difficult.
- Performing impact calculations: IBK used a sophisticated approach for performing impact calculations of an CFRP open-rotor blade. These calculations are highly non-linear and lead to damage within the blades. IBK was able to perform these calculations and show that damages are within certain limits.
- Rotoraeroelasticity: Since this topic is one step above 'normal' aeroelasticitiy regarding difficulty and own IBK-code was used in order to make sure that no flutter occurs. Apart from just looking at a certain conditions a whole range of flight situations was under review in order to make sure that no flutter arises during flight.
Potential impact:
Since this project was very well included into the process of other projects within SFWA / Clean Sky, the actual benefit of a single, very focused, short running project is difficult to disseminate. However, some things can be said about this topic:
IBK will address this project as a reference project for certain competences (rotoraeroelasticity, structural optimisation and weight saving) on its homepage. The actual results of the project are not publishable, because the main focus was not to establish new methods of means but to use existing tools and combine them for a certain goal (establish models for subsequent analysis). So the project was an enabler for future research and development (R&D) work done by NLR, DLR, ONERA.
Regarding the socio-economic impact none is available.
The DECROR project consists of the IBK company as sole partner and therefore coordinator. IBK is a small and medium-sized enterprise (SME) located in Germany with a long history as research and technological development (RTD) service provider in the fields of structural mechanics, fluid mechanics and couplings of both domains. With this project IBK was introduced into WP2222 of 'Smart fixed wing aircraft' (SFWA). During the IBK project worked on the 'Design of counter-rotating open rotors' (DECROR). Work combining different disciplines in mechanical engineering was performed, the results were delivered and discussed with the partners. Due to some late input the project itself had to be extended for six months, without an effect on costs.
Project context and objectives:
The DECROR project consists of the company IBK as sole partner and therefore coordinator. IBK is an SME located in Germany with a long history as RTD service provider in the fields of structural mechanics, fluid mechanics and couplings of both domains. With this project IBK was introduced into WP2222 of SFWA.
DECROR tackled the structural design of real-scale as well as wind-tunnel models for a counter-rotating open rotor. The work for this project was structured in two main phases: In the first phase the focus was on wind-tunnel models with different scales and different operating conditions (takeoff, cruise). Using Input from partners (Airbus, NLR, DLR, ONERA) IBK created a structural finite element (FE) model and performed different calculations.
- The testing in a wind tunnel has high-strength requirements therefore it was to be made sure that the blades do not fail.
- It is important that the eigenfrequencies of the blades are not excited during the tests. Therefore, an eigenvalue analysis was performed under operation conditions in order to make sure that the blades can be tested safely.
- For the final manufacturing it was important to calculate a so called 'Cold-Shape', meaning a shape that deforms under operating conditions into the so called 'Hot-Shape' or design-shape, the geometry that was used during the design. Calculating this shape was performed by IBK.
As results of this first phase wind-tunnel models for three different scales were created and delivered to the partners of WP2222 for subsequent analysis.
In the second phase of the project the focus shifted to the real-scale models. Using design-loads delivered from Airbus IBK performed the structural design using different blade-design approaches, optimising skin and spar positions and thicknesses and comparing different solutions with each other. Main driver was saving weight; however, all necessary requirements had to be fulfilled.
- Strength: The blade was not allowed to fail.
- Fatigue: The blade had to endure a certain number of load-cycles.
- Aeroelasticity: No flutter during the operating conditions.
- Impact: Using tyre-impact conditions a simplified calculation was performed showing that after the impact occurred the blade could sustain all damages during the impact.
- Stability: The eigenfrequencies of the blade may not be excited during the blade operation.
As result again FE models were created which were delivered to the partners for subsequent analysis.
As a major outcome for IBK it can be said:
IBK performed all actions necessary for rotor-design in-house. Especially the impact analysis of a carbon-fibre-reinforced polymer (CFRP) structure is a very challenging task and could be performed creating special routines needed for these kinds of calculations. IBK created different software solutions and processes, especially for:
- performing eigenfrequency calculations based on non-linear FE results taking into account centrifugal effects;
- design of CFRP parts using a structural optimiser in a semi-automatic process;
- methods for performing impact-calculations using a conservative approach.
Project results:
Againg, since this is way a very strongly focused projects which was intended to deliver input needed for the work of other partners within the SFWA integrated technology demonstrator' (SFWA-ITD) the results in terms of foregrounds are difficult to assess.
IBK performed a lot of very complex steps during this project:
- Eigenvalue calculations of rotating elements including centrifugal stiffening effects: Although this work is done using standard-software the actual adaption for a CFRP material and a non-linear calculation procedure is difficult.
- Performing impact calculations: IBK used a sophisticated approach for performing impact calculations of an CFRP open-rotor blade. These calculations are highly non-linear and lead to damage within the blades. IBK was able to perform these calculations and show that damages are within certain limits.
- Rotoraeroelasticity: Since this topic is one step above 'normal' aeroelasticitiy regarding difficulty and own IBK-code was used in order to make sure that no flutter occurs. Apart from just looking at a certain conditions a whole range of flight situations was under review in order to make sure that no flutter arises during flight.
Potential impact:
Since this project was very well included into the process of other projects within SFWA / Clean Sky, the actual benefit of a single, very focused, short running project is difficult to disseminate. However, some things can be said about this topic:
IBK will address this project as a reference project for certain competences (rotoraeroelasticity, structural optimisation and weight saving) on its homepage. The actual results of the project are not publishable, because the main focus was not to establish new methods of means but to use existing tools and combine them for a certain goal (establish models for subsequent analysis). So the project was an enabler for future research and development (R&D) work done by NLR, DLR, ONERA.
Regarding the socio-economic impact none is available.
