In this paper, the differences between a performance analysis of a wind turbine by computational simulations and by experimental methods such as tests in the wind tunnel ”GroWiKa” belonging to the TU Berlin are analysed. The qualitative and quantitative aspects of both the rotor of the turbine and its electric generator are analyzed under specific experimental methods whose resulting graphs are compared with simulation software such as Qblade for rotor performance and Open AFPM for electric generator performance. Finally, from this comparison, an analysis is derived by which the accuracy of the information obtained by the used software is validated.
Due to the recent climate crisis and new trends regarding the development of energy production, wind energy has become one of the most used solutions in the field of renewable energies. This technology offers efficiencies and performance even beyond energy production systems such as solar energy and even internal combustion engines based on biodiesel. Another convenience of wind energy is the fact that it has a wide potential for places even hard to reach by other technologies. But, just as it has a great number of advantages, it also has disadvantages because it is a technology that is still under development and its mode of implementation depends on a great number of variables such as mechanical, electrical and climate factors that must be taken into account when developing the different types of projects.
Table of Contents
1. Introduction
2. Simulation
2.1. Rotor characteristic curve
2.2. Generator characteristic curve
3. Measurements
3.1. Rotor
3.2. Generator
4. Comparison
4.1. Rotor
4.2. Generator
4.2.1. Possible Sources of Error
5. Conclusion
Objectives and Research Themes
The primary objective of this paper is to evaluate the performance of a handcrafted small wind turbine by comparing experimental measurement data against computational simulation models created in Qblade and OpenAFPM. The research addresses the accuracy of open-source simulation tools when applied to non-industrial, manually constructed prototypes.
- Comparative analysis of simulation versus experimental performance data
- Evaluation of Qblade for rotor aerodynamics and performance prediction
- Assessment of OpenAFPM for generator characteristic modeling
- Identification of error sources in handcrafted turbine manufacturing
- Impact analysis of variable test conditions on wind turbine efficiency
Excerpt from the Publication
2.1. Rotor characteristic curve
To simulate the operational conditions and obtain the rotor characteristics the software Qblade was used. It is important to take into account following considerations when simulating with Qblade:
• Reynolds number iteration: the Reynolds number is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. It is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities [4]:
Re = ρuL / μ = uL / ν (1)
where ρ is the density of the fluid (kg/m3), u is the flow speed (m/s), L is a characteristic linear dimension (m), μ is the dynamic viscosity of the fluid (kg/ms) and ν is the kinematic viscosity of the fluid (m2/s). As we can see in the definition and considering our measurement data from ”GroWiKa” it is not possible to calculate accurately the Reynolds number. In this case, and starting with a supposed Reynolds Number of Re = 10^6, an iteration must be executed until acceptable realistic results of the parameter ΔRe, which represents the discrepancy between simulation and reality (ΔRe < 2 · 10^6), are obtained [5]. As we observe in the Figure 1, after the first iteration, which give us already an acceptable result, we observe a decrease in the Power coefficient cP of the rotor.
Summary of Chapters
1. Introduction: Outlines the rise of wind energy as a renewable solution and introduces the scope of the study, which compares simulated data with experimental results from the "GroWiKa" wind tunnel.
2. Simulation: Details the theoretical modeling process using Qblade for the rotor and OpenAFPM for the generator, highlighting the input parameters used for the software.
3. Measurements: Describes the experimental setup at the TU Berlin "GroWiKa" facility, explaining the sensors and methods used to collect real-world performance data from the handcrafted turbine.
4. Comparison: Analyzes the discrepancies between simulation outputs and measured performance, including a dedicated section on the potential sources of error like sensor accuracy and manual manufacturing imperfections.
5. Conclusion: Summarizes that while simulation software is a powerful and accurate development tool, results must be reconciled with experimental realities such as manufacturing tolerances and testing vibrations.
Keywords
Wind Energy, Wind tunnel, Simulation, Measurements, Qblade, OpenAFPM, Rotor, Generator, Performance analysis, Reynolds number, Renewable energy, BEM, Experimental data, Error analysis, Handcrafted turbine
Frequently Asked Questions
What is the primary focus of this research paper?
The paper focuses on comparing the performance characteristics of a handcrafted small wind turbine obtained through computational simulations against actual experimental data collected in a wind tunnel.
Which simulation tools were utilized in the study?
The study employed Qblade for analyzing rotor performance and OpenAFPM for modeling the electric generator characteristics.
What is the core research objective?
The aim is to validate the accuracy of open-license simulation software by comparing its predictions with measurements derived from a physical, hand-built wind turbine prototype.
Which scientific methodology was applied?
The authors utilized a comparative methodology, using the Blade Element Method (BEM) for rotor simulations and Finite Element Method Magnetics (FEMM) for generator simulations, followed by lab-based experimental validation.
What does the main body of the work cover?
The main body covers the setup of the simulation environment, the experimental testing procedures at the "GroWiKa" facility, and a detailed cross-comparison of power and torque results.
What are the key themes characterizing this work?
Key themes include renewable energy technology, performance optimization, simulation-reality validation, aerodynamic analysis, and error propagation in small-scale engineering.
Why was there a discrepancy between the simulation and experimental results?
Discrepancies arose primarily due to the handmade nature of the rotor, sensor measurement errors, testing vibrations, and the fact that some simulation parameters were assumed rather than measured precisely.
How did mechanical clearance affect the generator performance?
The study observed that small variations in mechanical clearance (e.g., 0.5mm) led to significant differences in power output, indicating that physical construction tolerances have a large impact on final performance.
What was the role of the "GroWiKa" in this project?
The "GroWiKa" (großer Windkanal) at the TU Berlin served as the experimental testbed where the physical rotor and generator were subjected to real-world wind conditions to generate validation data.
How is the Reynolds number handled in the Qblade simulation?
Because accurate Reynolds number calculation was difficult, the study performed an iterative process starting from a base of Re = 10^6 to reach an acceptable convergence between simulated and real-world conditions.
- Citation du texte
- Shivaraj Patil (Auteur), 2019, Comparisons between simulation and measurements of a handcrafted small wind turbine, Munich, GRIN Verlag, https://www.grin.com/document/981428
