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One of the main problematics of the seals tests is the time and money consuming they are. Up to now, there are few tries to do a digitalisation of a test where the seals behaviour can be known.
This work aims to digitally reproduce a seal test to extract their behaviour when working under different operation conditions to see their impact on the pimp’s efficiency. In this thesis, due to the Lomaking effect, the leakage and the forces applied on the stator will be the base of analysis.
First of all, among all the literature available for very different kind of seals and inner patterns, it has been chosen the most appropriate and precise data. The data chosen is “Test results for liquid Damper Seals using a Round-Hole Roughness Pattern for the Stator” from Fayolle, P. and “Static and Rotordynamic Characteristics of Liquid Annular Seals with Circumferentially/Grooved Stator and Smooth Rotor using three levels of circumferential Inlet-Fluid” from Torres J.M.
From the literature, dimensions of the test rig and the seals will be extracted to model them into a 3D CAD software. With the 3D CAD digitalisation, the fluid volumes for a rotor-centred position, meaning without eccentricity, will be extracted, and used. The following components have been modelled:
- Smooth Annular Liquid Seal (Grooved Rotor)
- Grooved Annular Liquid Seal (Smooth Rotor)
- Round-Hole Pattern Annular Liquid Seal (𝐻𝑑=2 𝑚𝑚) (Smooth Rotor)
- Straight Honeycomb Annular Liquid Seal (Smooth Rotor)
- Convergent Honeycomb Annular Liquid Seal (Smooth Rotor)
- Smooth Rotor / Smooth Annular Liquid Seal (Smooth Rotor)
As there is just one test rig, all the components have been adapted to the different dimensions of the seals by referencing some measures. This allows to test any seal with the same test rig.
Afterwards a CFD simulation that will be used to obtain leakage and stator forces. The parameters that will be changed are the rotational velocity of the fluid (2000 rpm, 4000 rpm, and 6000 rpm) and the pressure drop (2,068 bar, 4,137 bar, 6,205 bar, and 8,274 bar).
Those results will be compared to the literature ones, and they will determine if digitalisation can be validated or not. Even though the relative error is higher than 5% but the tendency is the same and it is thought that by changing some parameters the test results can be even closer to the literature ones.
To date, many experiments have been performed to study how the internal geometrical shapes of the annular liquid seal can reduce internal leakage and increase pump efficiency. These can be time-consuming and expensive as all rotordynamic coefficients must be determined in each case.
Nowadays, accurate simulation methods to calculate rotordynamic coefficients of annular seals are still rare. Therefore, new numerical methods must be designed and validated for annular seals.
The present study aims to contribute to this labour by providing a summary of the available test rig and seals dimensions and experimental results obtained in the following experiments:
− Kaneko, S et al., Experimental Study on Static and Dynamic Characteristics of Liquid Annular Convergent-Tapered Seals with Honeycomb Roughness Pattern (2003) [1] − J. Alex Moreland, Influence of pre-swirl and eccentricity in smooth stator/grooved rotor liquid annular seals, static and rotordynamic characteristics (2016) [2]
A 3D CAD simulation with Siemens NX Software of the test rig used in J. Alex Moreland’s experiment has been made. The following annular liquid seals have also been 3D modelled, as well as their fluid volume:
− Smooth Annular Liquid Seal (SS/GR) (J. Alex Moreland experiment)
− Grooved Annular Liquid Seal (GS/SR)
− Round-Hole Pattern Annular Liquid Seal (𝐻𝑑=2 mm) (GS/SR)
− Straight Honeycomb Annular Liquid Seal (GS/SR)
− Convergent Honeycomb Annular Liquid Seal (No. 3) (GS/SR)
− Smooth Annular Liquid Seal (SS/SR) (S. Kaneko experiment)
In the case of the seals used in S. Kaneko’s experiments, the test rig has been adapted to each seal, defining interpart expressions which can be easily modified.
Afterwards, it has been done a CFD simulation of the Smooth Annular Liquid Seal using Ansys CFX Software. To do so, the fluid volume geometry has been simplified to do a first approximation. Results have been compared for an eccentricity 𝜀0=0.00 for the following ranges of rotor speeds and differential of pressure:
− Δ𝑃= 2.07, 4.14, 6.21, and 8.27 bar,
− 𝜔= 2, 4, 6 and 8 krpm.
Even results obtained have the same trend as the one proportionated by the literature, they cannot be validated as the error is above 5%. It is also observed that as the pressure drop increases, the relative error decreases considerably.
The present document is aimed to propose a suitable thermal model for the cooling down process of a one piston air cooled reciprocating compressor. In order to achieve this, a thermographic camera is used to record the temperature of different measuring points throughout different operating conditions. This data is later analyzed, with statistical tools and graphical visualization. The thermal phenomena present in the thermal process is characterized according to the compressors' geometry. Finally, using the analysis and taking into consideration the thermal phenomena the optimal thermal model is selected. This paper belongs to a bigger project and the last step is to simulate the compressor and the accuracy of the proposed model.
Schluckspecht project
(2022)
The Project "Schluckspecht" of the University of Offenburg consists of participating in the European marathon called "Shell Eco-Marathon"(SEM) which consists of designing and building from the beginning a vehicle with the greatest possible energy efficiency. The University of Offenburg has participated in this project since 1998.
The team that forms the Schluckspecht project is made up of around 30 students from the faculties of mechanical engineering, process engineering, electrical engineering, medical technology and computer science, as well as the degree in Audiovisual Communication. The team was founded in 1998 and since then students have been developing and building high efficiency vehicles to participate in the European marathon Shell Eco.
In this project, students can put into practice all the theoretical knowledge obtained during their studies. Also can be learned how to work interdisciplinarity as a team, a skill that for now, many companies or require or seek.
The following topics are discussed in the Schluckspecht project, which are also ideal for the work of students:
-Conception construction and production of high efficiency vehicles.
-Computational design and manufacture of lightweight components and sets.
-Development of lightweight components and sets from renewable raw materials.
-Construction and development of special test benches, for example: motor test bench.
-Implementation and optimization of control strategies for autonomous driving
-Mechanical and electrical integration of sensors for autonomous driving
-Ergonomic studies and optimization of the driver's cabin.
The objective of the project is to develop and manufacture research vehicles that make individual mobility as efficient as possible from an energy point of view. To achieve this, current and future issues of the industry are discussed. In this project, both the theoretical and practical part of the light construction of vehicles and the reduction of friction, the variety of propulsion concepts (electric thrusters, fuel cells, diesel/petrol engines, Stirling engines) and autonomous driving are investigated. The services of the University of Offenburg together with some external partners are grouped together to make this wonderful project work.
The Projekt-Sweaty is a project of the University of Applied Sciences of Offenburg, an autonomous robot is being developed that competes against a set of several international colleges and universities in the RoboCup.
"Sweaty" is a soccer-playing humanoid robot who participated in the RoboCup World Cup in Brazil for the first time in 2014.
RoboCup is a competition aimed at developing a robot soccer team that surpasses the human world champion team. The competition started in 1997 the first official RoboCup games and conferences were held with great success. More than 40 teams took part and more than 5,000 spectators attended. RoboCup’s rules change to promote advances in robot science and technology and to bring the league’s challenges closer to the real world.
Building a robot that plays football will not in itself generate a significant social and economic impact, but the realization will certainly be considered an important success for the field of robotics.
Thanks to the interaction of all the faculties, the team consists of professors and students from the fields of mechanical and process engineering, electrical engineering, information technology, and information and media technology. Students can use the project during their studies and use the knowledge acquired in practice to implement and through their own creative ideas complement.