Wind Tunnel Experiment of Bluff Body Aerodynamic Models Using a New Type of Magnetic Suspension and Balance System

Abstract

We have measured drag coefficients of a sphere and a circular cylindrical aerodynamic model using a five axes and a six axes control magnetic suspension and balance system (MSBS) developed by us. This MSBS has the characteristics of large aperture relative to the weight, light weight, and small electric power consumption in comparison with the conventional ones. We had good agreements between the measured values of the drag coefficient and the values appearing in the common aerodynamic handbook or textbook. We also succeeded in measuring the aerodynamic influence of a supporting rod of the aerodynamic models making use of the characteristics of the MSBS. Conventionally, the MSBS can be used only in large scale laboratories because the size, weight, and electric power consumption are large. We think that successful measurements of various aerodynamic characteristics using this type of MSBS will stimulate the introduction of it into the wind tunnel experiments in small scale laboratories.

Upstream wind tunnel model mounting: The forgotten method for road vehicle aerodynamics

“…However, the inclusion of rotating wheels and/or a moving ground was not easily attainable, with this technique also suffering from high initial costs, significant inherent complexity and large power requirements. 44 Supporting the model at the front or upstream is another option. This methodology has been used in the past within the aerospace industry to test free-flight sub-scale aircraft models, 45 but appears largely overlooked for ground vehicle applications; this omission being perhaps a result of the expectation that any upstream disturbance may be detrimental to the natural evolution of the aerodynamics.…”

“…However, the inclusion of rotating wheels and/or a moving ground was not easily attainable, with this technique also suffering from high initial costs, significant inherent complexity and large power requirements. 44…”

Digital Control Analysis and Design of a Field-Sensed Magnetic Suspension System

“…Magnetic suspension systems (MSSs) are important in several engineering applications [ 1 , 2 , 3 , 4 ], such as the levitation of high-speed Maglev trains [ 1 , 2 ], frictionless bearings [ 3 ], and wind tunnels [ 4 ]. Maglev trains travel a contactless guideway using magnetic suspension, therefore the friction is reduced and the speed is faster than possible with wheeled trains.…”

“…One aspect is analog modeling and the other is digital modeling. Numerous studies [ 1 , 2 , 3 , 4 , 5 , 6 ] have analyzed and designed MSSs by using analog control models. In this study, an MSS was analyzed and designed using a digital control model [ 7 , 8 ].…”

“…Bittar and Sales [ 3 ] proposed H 2 and H∞ controls, which are based on the analysis and design of the frequency domain and the analog case. Zhang et al [ 4 ] established the state feedback linearized suspension module control system model. A PID control method was used to stabilize the suspension module control system model.…”