Wind tunnel technology
6.5m × 5.5m low-speed wind tunnel
Since the days of the Wright brothers, wind tunnels have been effective and indispensable tools in developing aircraft and spacecraft. Experiments using wind tunnels on the ground (Experimental Fluid Dynamics, EFD) have been constant parts of the preparation for manufacturing and flight testing actual aircraft. JAXA operates and maintains Japan's largest wind tunnel facilities, which boast a wide range of speeds and sizes, and has been offering them to users together with innovative measuring methods and testing techniques. Wind tunnel users include Japanese manufacturers and educational institutions; in fact, JAXA’s wind tunnels have also been used to test most of the aircraft and space vehicles that have been developed and manufactured in Japan.
To provide higher-accuracy and higher-quality data more efficiently and to prepare for the future needs of aircraft and spacecraft development, we continue to advance our R&D on wind tunnel technologies.
The aim of the DAHWIN system is to improve the efficiency, accuracy, and reliability of aerodynamic characteristics evaluation for aerospace vehicles. DAHWIN is the world's first full-scale hybrid system that integrates the analysis of wind tunnel-based experimental fluid dynamics (EFD) with that of computer-based computational fluid dynamics (CFD). Maximizing the respective benefits and compensating for the imperfections of EFD/CFD, the DAHWIN system makes it possible to provide higher precision data more accurately and more effectively.
The keys to increasing accuracy and efficiency in a 2m × 2m transonic wind tunnel are automating, operating, and maintaining the drag flap, which can enable highly accurate control of the uniform stream Mach number when the operator changes the model attitude, in the process of making the high-accuracy sweep mode practically viable. We are also working on improving manual operability and performing high-efficiency, high-accuracy tests via a partially manual setup.
By using image-processing methods to create high-resolution images of sound pressure distributions and performing simultaneous acoustic and optical measurements, JAXA will develop technologies for identifying the aerodynamic phenomena that noise can cause.
This study focuses on developing technologies that make it possible to visualize and identify the positions of shockwaves on the upper surface of an aircraft wing, which have a sizable impact on aerodynamic characteristics in actual flight tests, technologies that enable users to conduct detailed pressure distribution measurements, and technologies for gathering extensive data on wing deformation.
JAXA is developing technologies for identifying where buffet occurs in three-dimensional flow fields and evaluating the detailed structure of flow fields by applying unsteady PSP and time-resolved PIV approaches. We will also conduct experiments to develop optimization methods for determining ideal device configurations and arrangements in designing devices that help resolve transonic buffet issues.
This study aims to establish clear correction boundaries of Raynolds number by making the most effective possible use of the available technologies. Quantifying the differences between the results from high Reynolds number wind tunnel tests and the results of computational fluid dynamics (CFD)-based predictions will also form a foundation for establishing aerodynamic characteristic prediction technologies within the context of the Reynolds numbers that actual aircraft encounter.
This study aims to support HTV-R research by ensuring the necessary testing capabilities for predicting the wide array of aerodynamic characteristics that the phases of re-entry bring about.
To improve the accuracy of aerodynamic characteristic prediction for aircraft and spacecraft, JAXA is developing technology that enables complementary and integrative analysis of large-scale EFD/CFD data, thereby extracting useful information, applying the findings for a better understanding of fluid phenomena.
JAXA is developing a new method to enable quantitative measurements with sufficient resolution by the oil flow approach.
Optical measurement technologies using cameras and lasers are non-intrusive approach that enables to acquire various and large amount of information of the flow fields around the wind tunnel test models. JAXA has developed three optical measurement technologies for wind tunnel testing: pressure measurement technology using pressure-sensitive paint (PSP), which changes color in response to the pressure acting on the model; particle image velocimetry (PIV), which mixes microscopic oil particles into the flow to measure flow velocity; and model deformation measurement (MDM), which measures deformation and displacement of the wind tunnel model such as the wing bending caused by lift.