Masataka Kohzai

Transonic Wind Tunnel Simulation with Porous Wall and Support Devices

In order to achieve highly accurate wind tunnel testing, a sophisticated method for wall and support correction is necessary. We simulated the ONERA-M5 model installed in the JAXA 2m2m Transonic Wind Tunnel (JTWT) considering the wall and support devices to investigate their interferences. The porous wall at the test section is also considered with a new model developed. The pressure on the porous wall is compared with the measurement. The results obtained from the simulation agree with the measurements. The features of wind tunnel flow including the porous wall flow were revealed from the simulation. The computed force and moment move closer to measurements, when the support and wall are considered and sufficient grid resolution is employed. Comparing the results, we calculated the support and wall interferences for CL, CD, and Cm. The CD is the most affected by the support and wall. Especially, the support interference is large for this model and support devices. The wall interference is +5counts, the support interference is -28counts, and the total interference is +23counts. In addition, we clarified the components affected by the support and wall for CL, CD, and Cm. As for the CD, the support affects all components, whereas the wall affects mostly main wing.

Analysis of NASA Common Research Model Dynamic Data in JAXA Wind Tunnel Tests

The JAXA 2m x 2m Transonic Wind Tunnel (JTWT) conducted tests for 80% scaled NASA Common Research Model (CRM). The dynamic data including buffet measurement with strain gauges and dynamic pressure sensors were acquired at 50,000 Hz sampling rate. A prediction of buffet phenomenon is one of important factors to design aircraft. If buffet phenomenon occurs, dynamic bending and torsion moment are measured with wing-root strain gauges. Spectrum analyses are being executed for the strain gauges and dynamic pressure data. It is expected to observe dynamic flow separation at points around where the relation with lift coefficient data and pitching moment coefficient is non-linear. This paper describes overview of the tests and the analysis data.

80% Scaled NASA Common Research Model Wind Tunnel Test of JAXA at Relatively Low Reynolds Number

A wind tunnel test of a 80% scaled copy of the NASA Common Research Model (CRM) was performed in the 2m × 2m transonic wind tunnel of Japan Aerospace Exploration Agency (JAXA). The wind tunnel model was fabricated by JAXA consulting NASA Langley Research Center and the Drag Prediction Workshop committee members. The test was conducted at relatively low Reynolds number of 2.27 × 10 due to the limitation of the tunnel capability and boundary layer transition was simulated with optimized roughness. In the test campaign, static pressure distribution and aerodynamic forces were successfully acquired while the model main wings were deformed during the test due to the dynamic pressure. To make a fair comparison with the data from other sources in different circumstances, data normalization techniques were applied. Then, the data was compared with the data of the National Transonic Facility of NASA and CFD. The data normalization successfully realized fair comparisons for pressure distribution and lift coefficients while the tests were performed at the different circumstances such as the different Reynolds numbers.

Wall and Support Interference Corrections of NASA Common Research Model Wind Tunnel Tests in JAXA

In the JAXA 2m x 2m Transonic Wind Tunnel (JTWT), there have been more needs of wind tunnel users for high measurement accuracy to develop aircraft and launch vehicles with high performance. Integration modern test techniques of the JTWT have to be established. Wind tunnel tests with an 80% scaled NASA Common Research Model (CRM) are conducted to validate our results. Errors of balance output due to balance calibration temperature are confirmed. The test section Mach number, the clear tunnel buoyancy, the wall interference, and the upflow angle corrections are integrated and applied to the CRM wind tunnel tests data in the JTWT. Support interference effects with results of CFD with support and CFD without support are investigated. Moreover, our wall interference correction results and support interference effects are compared with wall interference corrections of the NASA National Transonic Facility (NTF) and the NASA Ames 11-ft Wind Tunnel, and support interference effects of the NTF. Thus, these results show that aerodynamic data, which are not affected by wind tunnel, can be estimated more precisely by the application of the balance calibration matrix, fundamental wind tunnel interference corrections, and the support interference correction appropriately.

Experimental and Numerical Studies of Support Interference in the JAXA 2m x 2m Transonic Wind Tunnel

[Abstract] In the JAXA 2m x 2m Transonic Wind Tunnel, there have been more needs of wind tunnel users for high measurement accuracy to develop aircraft and launch vehicles with high performance. To improve the accuracy of flight data prediction from force measurement data in the wind tunnel, effects of the test section walls and the model support interference need to be corrected precisely in consideration of the mutual interference. Effects of the support interference, especially sting-strut system interference, with porous walls are analyzed by comparisons between a calibration model supported with a standard sting and with a long one in wind tunnel testing and CFD. The sting-strut support interference correction method derived from the CFD results is applied to the wind tunnel data. It is confirmed that the effects of the support interference on the model can be appropriately corrected by applying Mach number correction and buoyancy correction methods to forebody drag. Moreover, CFD analysis of the test section surrounded with porous walls has been improved to investigate the wall and the support interference including the mutual interference.

Normalization of Wind-Tunnel Data for NASA Common Research Model

A wind-tunnel test of an 80%-scale copy of the NASA Common Research Model was performed by the Japan Aerospace Exploration Agency using its 2  m×2  m transonic wind tunnel. The wind-tunnel model was fabricated by the Japan Aerospace Exploration Agency in consultation with NASA Langley Research Center and AIAA Drag Prediction Workshop committee members. The static aerodynamic forces and surface pressure distributions on the wing of the Japan Aerospace Exploration Agency model were measured at a relatively low Reynolds number of 2.27×106 due to tunnel capability limitations, where boundary-layer transition was simulated using optimized roughness. Measured data were compared with those of wind-tunnel tests of the Common Research Model obtained from NASA Langley Research Center’s National Transonic Facility as well as computational fluid dynamics predictions, both at a Reynolds number of 5.0×106. The comparison among these datasets required data normalization to the designed shape aligned at a reference condi...

Wall Interference Analysis of Transonic Wind Tunnel with Porous Wall Model

In order to achieve highly accurate wind tunnel testing, a sophisticated method for wall and support correction is necessary. Flows around the ONERA-M5 model installed in the JAXA 2m×2m Transonic Wind Tunnel (JTWT) have been simulated considering the wall and support devices to investigate their interferences. The wing span to width ratio is 49% for the ONERA-M5. To investigate the support influence, two lengths of sting are simulated at attack angle of 0o for M=0.7 and 0.84. The porous wall at the test section is also considered with a new porous model. The pressure on the porous wall is compared with the measurement, and the results obtained from the simulation agree well with the measurements. The computed force and moment also show good agreement with the measurements. The results indicate that the buoyancy effect due to the support system is not affected so much by the wall since the difference due to the sting length is not changed by the wall. Moreover, it is found that the difference in CD and Cm due to the wall is so small, and only CL is affected by the wall. Since the model scale is relatively small, the wall interference and mutual interference between wall and support system are small in this study. The Cp difference due to the wall appears mainly near the leading edge of main wing for M=0.7. For M=0.84, the difference is mainly near the shock wave location on the main wing. In addition, the differences of attack angle and Cp around the model are revealed by this simulation.