Project Description: The hybrid motor is using pressurized N2O as the combustion oxidizer. The current tank is made out of aluminium and is quite heavy. The goal of this project is to reduce its total mass. The tank has to sustain a maximal pressure of 60 bars and designs proposed shall include one-end opening and two-ends opening. The dimensions will be defined during the project.

The project’s phases are the following:

1. Documentation research, manufacture opportunities
2. Discussion of designs solutions
3. Dimensions freeze
4. Design, Calculations and simulations
5. Manufacture and tests (if possible)

Timeframe: Spring 2020

Number of participants: 2

Contact: theophile.balestrini@epfl.ch

Project Description: The injector is used to spray, atomize and give a specific shape to the N2O flow. The goal of this project is to define more precisely the influence of the injector’s geometry on the N2O mass flow rate and to simulate the flow’s shape that exits the injector.

Figure 1 – Examples of studied injector’s geometries

The project’s phases are the following:

1. Documentation research, learn what has already been done
2. Discussion of designs solutions
3. Design, Calculations and simulations
4. Manufacture and cold flow tests (if possible)

Timeframe: Spring 2020

Number of participants: 2

Contact: theophile.balestrini@epfl.ch; michel.perraudin@epfl.ch

Project Description: The grain, currently made out of ABS and 3D printed, is the solid fuel that reacts with the oxidizer and creates the combustion gases. Its shape is a cylinder with a central port, where the combustion will occur. The goal of this project is to calculate an initial port geometry that will allow the most constant combustion surface trough the entire burn time and to find a better fuel composition.

The project’s phases are the following:

1. Documentation research, learn what has already been done
2. Discussion of designs solutions
3. Design, Calculations and simulations
4. Manufacture and hot fire tests (if possible)

Timeframe: Spring 2020

Number of participants: 2

Contact: theophile.balestrini@epfl.ch

Project Description: The hybrid motor holds a pressurized oxidizer (N2O) in a tank and uses an actuated valve to control its flow through the injector after which stays the grain (fuel, ABS) and where the combustion will occur. The goal of this project is, based on the previous work that has been done, to use the physical model of the engine to design a feedback control. This task will be performed by identifying the dynamic between the valve actuation and the measured values: thrust and pressures. The controller will need a state-space estimator for the physical values that can’t be measured.

The project’s phases are the following:

1. Documentation research, learn what has already been done
2. Design, Calculations and simulations
3. hot fire tests during which the system’s identification will be done
4. Regulator implementation on the control software (if possible)

Timeframe: Spring 2020

Number of participants: 2

Contact: theophile.balestrini@epfl.ch

Project Description: One of the biggest concerns for the design of the fins is the fin fluttering. It is an aeroelastic instability which involves both fluid and structure dynamics. Fluttering can have dramatic consequences and destroy the fins, resulting in a crash of the rocket. Therefore, it is essential to study this phenomenon and make sure to avoid it, especially for a supersonic flight because of the high velocity.

Your job: your work should start by a thorough literature review and it would be beneficial if you followed the aeroelasticity class by Mr. Farhat. The objectives of this project can be split into two parts:

• After literature research, develop an analytical model of the fins’ aeroelastic behavior. The goal is to get a feeling, intuition for fluttering and a basic understanding. It would also help to define the relevant parameters and their influence to orient the design iterations. From that, find some possible shapes that should not experience fluttering.
• Then, your job is to try to implement coupled fluid-structure simulation in Ansys to evaluate the different fin geometries. Try to find experiment data for fluttering and try to simulate it to check if your simulation corresponds to reality. To validate the final dimensions, several iterations will be needed with the simulation team and the overall design of the rocket to ensure the target apogee and rocket stability during flight.

Figure 1: fin fluttering, https://youtu.be/pyct1Pii_cg

You will also work closely with two other groups who will focus on pure fluid simulations and structural simulations and try to mix the information from both sides to design the fins. The coupled simulation will likely not be correct or not work at all. The backup option is to export a load case from the CFD simulation into a mechanical analysis software and solve separately. However, this method cannot model fin fluttering.

Timeframe: Spring 2020

Number of participants: 2-3

Contact: theo.grosgurin@epfl.ch

Project Description:

• Current state: several simulations have already been done to compare nose cone shapes and fin shapes. However, they were not very precise and took days of computing time although they were done on a reduced scale. This could be improved by working on the mesh, which is the critical element of CFD simulations.
• Input for you: you will get the previous reports which explain the main settings to use in ANSYS Fluent to simulate the compressible flow around a rocket and the first results. This will also include a detailed step by step procedure to run simulations on EPFL clusters.
• Your job: your work should result in a full-scale 3D computation of the flow around this year’s Bella Lui rocket for drag characterization to improve the flight predictions of our simulations team. This could include, if possible, a transient simulation for the whole range of velocities encountered during the flight. Else, you will use several steady state simulations at different altitudes and velocities. Finally, your mesh will be used for the next project of 2021 which goal is to reach 30’000 ft altitude and reach supersonic speeds. Therefore, your mesh shall be easily “transferrable” to another geometry. To recap, your tasks are:
  • Learn to use a CFD (Computational Fluid Dynamics) software, namely ANSYS Fluent.
  • Optimize the mesh to get meaningful results with reasonable computing time
  • Analyze and define the correct measures of your mesh quality. Perform a mesh convergence study.
  • Adjust the simulation settings to best fit real flight conditions (atmospheric properties).
  • Extract useful results from your simulation such as drag force, force on the nose cone and the fins (via the pressure field), surface temperature.

Figure 1: volume rendering of the pressure field (just to motivate you)

Note that this is a team project. You are expected to communicate the progress of your work to the other team members each week. At the end, your results shall be well documented such that other people can use or continue your work.

Timeframe: Spring 2020

Number of participants: 1-2

Contact: theo.grosgurin@epfl.ch

Project Description: The EPFL Rocket Team is an interdisciplinary project and an association which goal is to build a rocket and participate in an international competition in the USA. At the competition, the rocket must reach 10’000 feet (3048m) and in the future we will aim at 30’000 feet. The rocket must be recovered safely by deploying a parachute to slowdown the rocket before landing. At the rocket team, we would like to develop and fabricate a homemade parachute and that is where you can help us! The parachute must fit given requirements like the drag and the diameter to match a required descending speed. At the end, we would like to test the parachute in a wind tunnel to qualify it for flight and if the job is well done, it will be used for real at the competition!

Tasks

• Develop a parachute, define the shape, select material and fabrication techniques
• Fabricate the parachute
• Test and qualify it for flight
• Stay in close contact with the Rocket Team about the progress and collaborate with us

Timeframe: Spring 2020

Contact: mathieu.udriot@epfl.ch; alberic.lajarte@epfl.ch; karen.mulleners@epfl.ch

Project Description: The ERT Avionics subsystem is in charge of computing the state of the rocket thanks to its numerous on-board sensors. It is composed of various printed circuit boards (PCBs 1 ), assembled together on a structure whose main goal is to protect them from the loads and vibrations of the flight.

Problematic: Your role is to prove to the team that this structure will be able to sustain those loads and vibrations. For that, a FEM analysis must be carried onto the actual structure with various load cases, and a modal analysis shall also be conducted. Complementary tests on a vibration table should be expected, as they allow to compute the damping ratio of the structure and detect the critical areas of the structure where the vibrations have the biggest amplitude. The results shall be clearly exposed and explained; in case of a test failure, some improvements on the actual structure shall be proposed as implementations for next year.

Figure 1: Left: 2019 AV structure assembled with electronics hardware.

Right: example of vibration table (here the 80 kN Shaker table at ESA’s test centre in Noordwijk)

Timeframe: Spring 2020

This project can be done by one person as a bachelor project or semester project in Mechanical Engineering.

Contact: gabriel.tornare@epfl.ch; joel.cugnoni@epfl.ch

Project Description: The EPFL Rocket Team is an interdisciplinary project and an association which goal is to build a rocket and participate in an international competition in the USA. At the competition, the rocket must reach 10’000 feet (3048m). In this context, the ground segment team has been developing a camera tracker which goal is to direct a camera at the rocket at any time during its flight. This is useful for doing post-flight analysis and also to get a very nice video of the flight! So far, we are relying on manual input and simulation data for control. The hardware was manufactured and assembled by a student for a bachelor project, but is not entirely finished. We have a tripod and a structure with 2 plateau that can rotate along 2 axis thanks to 2 stepper motors, as shown in the schematic image.

The goal of the project we propose is to develop a software that could control the tracker using computer vision.

Timeframe: Spring 2020

Number of participants: 1

Contact: yann.vonlanthen@epfl.ch; stephanie.lebrun@epfl.ch

Project Description: The ERT Avionics subsystem is in charge of computing the state of the rocket thanks to its numerous on-board sensors. The sensors data is first extracted from the sensors then refined to obtain a cleaner state estimation through a Kalman filter. The performances of the Kalman filter depend on a lot of parameters which were not quantified.

Problematic: Your role is to work on the Avionics’ Kalman filter to characterize its performances. For that, you shall carry out an exhaustive assessment of the errors of the algorithm by analyzing every part of the process, from the choice of sensors (HW choice) to the definition of the state vector. As a testing tool, a Hardware-in-the-Loop (HIL) simulator has been designed and coded by the team and is accessible for testing and debugging. Some test flights onboard test rockets will be made to test and qualify the analysis results.

Timeframe: Spring 2020

This project can be done by one or two people as a semester project in STI.

Contact: gabriel.tornare@epfl.ch; phillipe.muellhaupt@epfl.ch; alireza.karimi@epfl.ch