scholarly journals A predictive controller for the Mach number in a transonic wind tunnel

1991 ◽  
Vol 11 (1) ◽  
pp. 63-72 ◽  
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Predictive Controller ◽  
Transonic Wind Tunnel

Interference Effects at Sonic Speeds for a Biconvex Aerofoil in a Wind Tunnel with Slotted Liners

1966 ◽  
Vol 70 (663) ◽  
pp. 446-448 ◽  
Author(s):  
W. J. Graham ◽  
A. G. J. MacDonald
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Static Pressure ◽  
Area Ratio ◽  
Interference Effects ◽  
Open Area ◽  
Sonic Speed ◽  
Reference Pressure ◽  
The Relationship ◽  
Transonic Wind Tunnel

The purpose of this note is to present some recently acquired data showing the effects of variations in the open area of slotted liners on the pressures on a twodimensional aerofoil at sonic speed in the 36 inch X 14 inch transonic wind tunnel at the NPL. The basic slotted liners for this tunnel have eleven longitudinal slots, giving an open-area ratio (σ) of 0.091. Other slot openings are obtained by closing appropriate slots with “Sellotape.” Nine values of σ ranging from 0 to 0.091, were used in this investigation. A wall static-pressure orifice, sufficiently far upstream of the model to be unaffected by its presence (3-6 chords), was used as a reference pressure for tunnel speed. The relationship between the Mach number given by this reference pressure and the true tunnel Mach number (M0), at the model location, was obtained by careful calibration.

scholarly journals Measurementimprovement of flow quality of slotted test section in transonic wind tunnel

2021 ◽  
Vol 39 (3) ◽  
pp. 660-667
Author(s):  
Shenghao Wu ◽  
Jiming Chen ◽  
Qin Chen ◽  
Haitao Pei
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Test Section ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Area Ratio ◽  
Straight Section ◽  
Flow Quality ◽  
Transonic Wind Tunnel

Experimental studies were carried out in the 0.6 m×0.6 m continuous transonic wind tunnel of CARDC in order to investigate the flow characteristics of the slotted test section. Experimental results show that the root-mean-square deviation of axial Mach number in the model area is above 0.01 when the test section Mach number is above 1.0.Numerical simulation under the same conditions to investigate the flow characteristics of the slotted section, together with the experimental studies indicate tow phenomena may directly cause the Mach number fluctuation. Firstly, a straight section was installed to connect the nozzle and the test section in the wind tunnel. Weak shock waves due to the curvature discontinuity at the joint of the test section and the straight section contribute to Mach number fluctuation. Secondly, the open-area ratio of both the upper and lower wall of test section, each with 8 slots, is of 10%. The larger porosity leads to stronger expansion waves in the acceleration zone located at the inlet of the test section. The flow was over accelerated because of the stronger expansion wave and thus fluctuate the flow field severely. Two measures were taken to improve the flow quality of the slotted test section based on the above-mentioned analysis: ①Flexible plate instead of solid straight plate was installed to bridge nozzle and test section to eliminate the curvature discontinuity; ②Decreasing the open-area ratio of the upper and lower test section wall to 6% and the number of slots to 6. Numerical and experimental results show that the Mach number fluctuation in the model area was suppressed to a satisfactory degree.

Heuristic open-loop output feedback model predictive control for control of intermittent transonic wind tunnel

2019 ◽  
Vol 42 (4) ◽  
pp. 832-839
Author(s):  
Jianchen Hu ◽  
Baocang Ding
Keyword(s):  
Steady State ◽  
Mach Number ◽  
Wind Tunnel ◽  
Predictive Control ◽  
Output Feedback ◽  
Total Pressure ◽  
Dynamic Control ◽  
Open Loop ◽  
Feedback Model ◽  
Transonic Wind Tunnel

For intermittent transonic wind tunnel (ITWT), Mach number and total pressure are crucial features of the flow field in the test section. However, they are typically difficult to control due to system nonlinearities, uncertainties, coupling and delays. This paper proposes an output feedback model predictive control (MPC) strategy to ensure the tracking of Mach number and total pressure of the ITWT to a specified reference trajectory. The proposed approach includes open-loop prediction, steady state target calculation (SSTC) and dynamic control, where the lower layer dynamic control tracks the steady state target obtained from the upper SSTC layer. By adding an artificial disturbance in the identified linear parameter varying (LPV) model for ITWT, and utilizing the resulting LPV model in both SSTC and dynamic control layers, a heuristic open-loop output feedback MPC approach is proposed. The experimental results for the control of Mach number and total pressure for ITWT demonstrate the effectiveness of the proposed approach.

Perturbation Analysis and Control of Mach Number 2.4-Meter Transonic Wind Tunnel

2020 ◽  
Vol 57 (6) ◽  
pp. 1148-1155
Author(s):  
Wenshan Yu ◽  
Ning Du ◽  
Zhengzhou Rao ◽  
Zhi Wei ◽  
Ping Yuan
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Perturbation Analysis ◽  
And Control ◽  
Transonic Wind Tunnel

scholarly journals A preliminary study on static pressure probe mobile measurement method for flow field in transonic wind tunnel

2021 ◽  
Vol 39 (4) ◽  
pp. 786-793
Author(s):  
Haijun Deng ◽  
Bo Xiong ◽  
Xinfu Luo ◽  
Shaozun Hong ◽  
Qi Liu ◽  
...  
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Flow Field ◽  
Static Pressure ◽  
Wind Tunnel Test ◽  
Flow Characteristics ◽  
Pressure Probe ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Wind Tunnel

The axial Mach number distribution of the core flow for model in a transonic wind tunnel is an important index to evaluate the performance of the flow field, which is usually measured by the centerline probe. In order to simulate the incoming flow characteristics without interference, the probe will extend from the support section to the shrinkage section, so the probe usually must has longer inches, more static pressure measuring points and smaller blockage requirements. In order to study the influence of the points of the centerline probe on the uniformity distribution of flow field, a new static pressure probe is designed, which is smaller and shorter than the centerline probe. On the basis of the stability of the flow field, the Mach number distribution of the flow field measured by the static pressure probe which is driven by the moving measuring mechanism. The characteristics of the measured values are studied by wind tunnel test. The results show that: when Ma ≤ 0.95, the overall distribution and value of Mach number obtained by the static pressure probe is basically the same as those obtained by the centerline probe, but some flow field details, which mainly shows that Mach number of the static pressure probe has smaller fluctuation, higher accuracy and better uniformity index.

scholarly journals Base Pressure in Transonic Speeds: A Comparison Between Theory and Experiment

1988 ◽  
Author(s):  
F. Motallebi
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Vortex Shedding ◽  
Base Pressure ◽  
Symmetrical Model ◽  
Base Bleed ◽  
Transonic Wind Tunnel ◽  
Theory And Experiment

The problem of base pressure in the absence of base bleed has been investigated for a symmetrical model with a square-cut trailing edge. The model was mounted at zero angle of attack in a transonic wind tunnel covering a range of mainstream Mach number from 0.6 to 1.3. The role of vortex shedding was found to be of great importance in the prediction of base pressure. A semi-theoretical analysis for the prediction of base pressure in subsonic and transonic speeds which includes the effect of vortex shedding is proposed.

Sign in / Sign up

Export Citation Format

Share Document