Development of a probe traversing system for an open test section wind tunnel

Transcription

1 Development of a probe traversing system for an open test section wind tunnel Gépészet 2012 Conference 24 th of May, 2012 Section Energy 2. Árpád Varga Mechanical Engineering Modelling MSc, Contractual student of Theodor von Kármán Wind Tunnel Laboratory

2 Content 1) Introduction Wind Tunnel tests, the LHWT at DFM Role of positioning on the field of aerodynamical measurements (examples connected to the topic of renewable energy production) 2) Presenting the LWTTS Operation requirements Structural design Aerodynamic design Electric systems and control 3) Future plans for development

3 Wind Tunnel tests CFD simulations Large Horizontal Wind Tunnel (LHWT) at Theodor von Kármán Wind Tunnel Laboratory (TKWTL) of Department of Fluid Mechanics (DFM) Recirculating, Göttingen-type tunnel, open test section

4 Role of positioning in aerodynamical measurements Varying the location and/or the orientation relative to the wind direction of the downscaled model inside the measurement section Wind loads acting on roof mounted solar arrays different wind directions (supermarket) Solar collector damaged by wind

5 Role of positioning in aerodynamical measurements Moving probes (pressure, velocity, temperature, concentration etc. sensors) into predetermined spatial points in order to map the distribution of selected physical quantities along curves or on surfaces. Boundary layer for building aerodynamics investigations

6 Role of positioning in aerodynamical measurements Moving probes (pressure, velocity, temperature, concentration etc. sensors) into predetermined spatial points in order to map the distribution of selected physical quantities along curves or on surfaces. Wind turbine wake measurements in wind tunnel wind farms J. Bartl: Wake measurements behind an array of two model wind turbines Master of Science Thesis, KTH School of Industrial Engineering and Management, Stockholm

7 Role of positioning in aerodynamical measurements Providing rigid, easily variable fixing stand for complementary instruments (laser light sources, optics, high speed camera etc.) applied during test. PIV measurement on a road vehicle model - fixing the mirror optics

8 Presenting LWTTS Large Wind Tunnel Traversing System (LWTTS) a new PC controlled, universal positioning system for probe and instrument positioning, designed according to special requirements (past experiences), structurally integrated to the test section of the LHWT

9 Operation requirements 1) Flow disturbance and any access limitation to the test section should not be allowed while the LWTTS is in its neutral parking position. 2) Limited amount of space for movement above the test section due to the structure of five component aerodynamic balance. 3) The range of available positions by the probe mounted on the LWTTS must cover the largest possible volumetric domain of the utilized measurement section. (The LHWT test section volume is 4m long and has a diameter of 2.6m.) 4) Sufficient structural stiffness in order to avoid the wind induced vibrations up to 40 m/s airspeed. 5) The LWTTS must be able to move and hold on position an arbitrary device (probe, laser optics, camera) with maximal overall dimensions in 100x100x100 mm and 2 kg in weight. 6) The precision of the positioning must be below 0.5 mm in horizontal direction and must not exceed 0.2 mm in vertical direction.

10 Operation requirements-lim. space above the test sect. Longitudinal Cross section of the LHWT

11 Structural design Cartesian manipulator with H-portal arrangement (milling machines) Conceptual design: T. Kerekes (BSc Thesis); Detailed CAD design: M. Balczó

12 Structural design X axis Linear bearings Guiding shafts with circular cross-section Standard BOSCH profiles with high bending stiffness

13 Structural design X axis drive Pulley Synchronizing shaft Guiding disks Tensioned toothed belt Scheme of the X-axis drive

14 Structural design Y axis Test assembly of the X and Y LWTTS axes at TKWTL Y axis standard linear drive unit with auxiliary linear guidance Additional guiding shaft for Y axis Y axis mounting plate

15 Structural design telescopic Z axis (Z1,Z2) Z2 Z1 Probe holding arm Two ball screw linear motion units (Z1, Z2), which are fixed rigidly to each other Original conception: T. Kerekes, 2005

16 Structural design telescopic Z axis fixed on Y mounting plate Y axis mounting plate Robust intermediate component Z axis

17 Aerodynamic design As parts of the LWTTS are exposed to the flow, the aerodynamic design was needed to: 1) decrease wind forces acting on the structure 2) avoid separating vortices which may cause vibrations to the system 3) to minimize disturbance of the flow (static pressure) Static pressure disturbance prediction (by A. Gulyás): Simplified 2D simulations of X axis carrige nose cover (30 m/s). Left: X axis X axis carrige cross-section reach the airjet in the mid-plane of the test section aluminium profiles without streamlined cover; Right: with asymmetric nose cover mounted on the forward beam.

18 Aerodynamic design the Y axis nose cover

19 Aerodynamic design the Z axis streamlined shell and the probe holding arm Symmetric composite airfoil cover profile for the Z1 axis Streamlined probe holding arm cross-section

20 Aerodynamic design the Z axis streamlined shell

21 Electic systems and control Power supply Stepper drivers Stepper motors Encoders Closed loop position control! PC interface Control softvare developed in LabVIEW Limit switches Energy chains

22 Electic systems and control Energy chains

23 Future plans for development 1)Sensor cable set-up Secondary energy chain system for sensor wiring 2)Precision measurements (Deflection of the X axis?) 3)Software development coincidence detection, measurement grid generator, automatic measurements, Z axis movement strategies (over-defined axis!)

24 Videos Ground testing U87Iu_JR-jPr-64BB5aKvUA&index=3&feature=plcp First movements in the test section of the LHWT UU87Iu_JR-jPr-64BB5aKvUA&index=1&feature=plcp

25 Thank you for your attention!