The NWTC Design-Codes Suite: An Overview

Abstract

Over the years, the National Renewable Energy Laboratory’s National Wind Technology Center (NWTC) has created a suite of design and analysis software tools for horizontal-axis wind turbines. The suite includes aeroelastic turbine simulators of various complexity, turbulent wind simulators, tools to aid in the design of control systems, pre- and postprocessing tools, and scripts to automate the running of simulations. A major goal of the NWTC staff in recent years has been to automate the flow of data between the programs to reduce the time and effort required to generate loads documents for type certification. The interoperability of the tools has been improved, and several codes have received significant upgrades in functionality, performance, and usability. This paper describes how the codes work together, lists recent improvements, and discusses proposed enhancements. I. INTRODUCTION Researchers at the National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory (NREL) have developed a comprehensive suite of software tools to aid in the design of horizontal-axis wind turbines (HAWTs) and to process simulation predictions and test data. Some of the programs developed by NWTC engineers many years ago now require updates to aid in maintenance and ease of use. Of the feedback the laboratory has received about the codes, the most common suggestion is that the users would like the codes to work together better. Although some of the programs require similar kinds of information as others in the suite, they sometimes required the information in different formats. When engineers switch tools, converting the information from one format to another wastes valuable time. Not only did the programs require the data in different formats, but also the formats of the input files varied. With these weaknesses in mind, engineers at the NWTC have put much effort into making their codes more compatible. Some of the codes now share their input files with other programs, and those that must be different share a similar look. Our code suite includes: • Programs that simulate the aeroelastic response and performance of HAWTs • Codes that are used to prepare data files needed by the simulators, analyze the results of the simulators, and analyze test data • Utility programs that automate the execution of series of simulations. This eliminates the tedious and mistake-prone requirement of manually editing input files and renaming output files for all the cases. Brief descriptions of the various codes follow, and an overview of how the codes interrelate is shown in Figure 1. Detailed descriptions of the various codes are available on the NWTC Design Codes web site. †1 Program archives on the web site include source code, executables (when appropriate), and sample input and output files. All the programs are in the public domain—anyone may use excerpts of our source code in her or his own programs.