Aerodynamic Drag Measurement in a High-Enthalpy Shock Tunnel

2018 ◽  
Author(s):  
Yunpeng Wang ◽  
Zonglin Jiang ◽  
Honghui Teng
Keyword(s):  
Natural Frequencies ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Shock Tunnel ◽  
Test Time ◽  
Test Duration ◽  
Flow State ◽  
High Enthalpy

Shock tunnels create very high temperature and pressure in the nozzle plenum and flight velocities up to Mach 20 can be simulated for aerodynamic testing of chemically reacting flows. However, this application is limited due to milliseconds of its test duration (generally 500 μs–20 ms). For the force test in the conventional hypersonic shock tunnel, because of the instantaneous flowfield and the short test time [1–4], the mechanical vibration of the model-balance-support (MBS) system occurs and cannot be damped during a shock tunnel run. The inertial forces lead to low frequency vibrations of the model and its motion cannot be addressed through digital filtering. This implies restriction on the model’s size and mass as its natural frequencies are inversely proportional the length scale of the model. As to the MBS system, sometimes, the lowest natural frequency of 1 kHz is required for the test time of typically 5 ms in order to get better measurement results [2]. The higher the natural frequencies, the better the justification for the neglected acceleration compensation. However, that is very harsh conditions to design a high-stiffness MBS structure, particularly a drag balance. Therefore, it is very hard to carried out the aerodynamic force test using traditional wind tunnel balances in the shock tunnel, though its test flow state with the high-enthalpy is closer to the real flight condition.

scholarly journals Intelligent Force-Measurement System Use in Shock Tunnel

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6179
Author(s):  
Yunpeng Wang ◽  
Zonglin Jiang
Keyword(s):  
Deep Learning ◽  
Measurement System ◽  
Force Measurement ◽  
Aerodynamic Force ◽  
Low Frequency ◽  
Shock Tunnel ◽  
New Method ◽  
Test Results ◽  
Force Measurement System ◽  
The Impact

The inertial vibration of the force measurement system (FMS) has a large influence on the force measuring result of aircraft, especially on some tests carried out in high-enthalpy impulse facilities, such as in a shock tunnel. When force tests are conducted in a shock tunnel, the low-frequency vibrations of the FMS and its motion cannot be addressed through digital filtering because of the inertial forces, which are caused by the impact flow during the starting process of the shock tunnel. Therefore, this paper focuses on the dynamic characteristics of the performance of the FMS. A new method—i.e., deep-learning-based single-vector dynamic self-calibration (DL-based SV-DSC) of an impulse FMS, is proposed to increase the accuracy of aerodynamic force measurements in a shock tunnel. A deep-learning technique is used to train the dynamic model of the FMS in this study. Convolutional neural networks with a simple structure are applied to describe the dynamic modeling so that the low-frequency vibration signals are eliminated from the test results of the shock tunnel. By validation of the force test results measured in a shock tunnel, the current trained model can realize intelligent processing of the balance signals of the FMS. Based on this new method of dynamic calibration, the reliability and accuracy of force data processing are well verified.

scholarly journals Vibration Energy Harvest for Low Frequency using Double- piezoelectric Cantilever Beam

2020 ◽  
Vol 306 ◽  
pp. 04006
Author(s):  
Chuttipong Tuma ◽  
Danai Phaoharuhansa
Keyword(s):  
Natural Frequencies ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Quadratic Equation ◽  
Energy Harvest ◽  
Cantilever Beams ◽  
Large Bandwidth ◽  
Piezoelectric Cantilever ◽  
Fea Simulation ◽  
Double Cantilever Beams

This study introduces design methods of natural frequency for double-piezoelectric cantilever beams in order to absorb electricity from mechanical vibration. The natural frequencies of double cantilever beams are designed by quadratic equation such as 6.45 and 18.14 Hz. On the other hands, FEA is used to recheck the result. FEA simulation presents the natural frequencies such as 4.4614, 8.4793, 13.8020 and 25.1050 Hz. It works in low frequency and large bandwidth. The experimental results show the peak electric power at 5 and 22 Hz. The error may occur by stiffness of piezoelectric and effective of mounting position.

Free-flight measurement technique in the free-piston high-enthalpy shock tunnel

2014 ◽  
Vol 85 (4) ◽  
pp. 045112 ◽  
Author(s):  
H. Tanno ◽  
T. Komuro ◽  
K. Sato ◽  
K. Fujita ◽  
S. J. Laurence
Keyword(s):  
Measurement Technique ◽  
Shock Tunnel ◽  
Free Flight ◽  
Free Piston ◽  
High Enthalpy ◽  
Flight Measurement ◽  
High Enthalpy Shock Tunnel

Testing methodologies in the DLR High Enthalpy Shock Tunnel HEG

1998 ◽  
Author(s):  
W. Beck ◽  
G. Eitelberg ◽  
O. Trinks ◽  
M. Wollenhaupt
Keyword(s):  
Shock Tunnel ◽  
High Enthalpy ◽  
High Enthalpy Shock Tunnel

scholarly journals The Relationship between Vibratory Sensation and Body Surface Vibration Induced by Low-Frequency Noise

2002 ◽  
Vol 21 (2) ◽  
pp. 87-100 ◽  
Author(s):  
Yukio Takahashi ◽  
Kazuo Kanada ◽  
Yoshiharu Yonekawa
Keyword(s):  
Body Surface ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
The Body ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Vibration Acceleration ◽  
Surface Vibration ◽  
Human Body Surface ◽  
The Relationship

Human body surface vibration induced by low-frequency noise was measured at the forehead, the chest and the abdomen. At the same time, subjects rated their vibratory sensation at each of these locations. The relationship between the measured vibration on the body surface and the rated vibratory sensation was examined, revealing that the vibratory sensations perceived in the chest and abdomen correlated closely with the vibration acceleration levels of the body surface vibration. This suggested that a person exposed to low-frequency noise perceives vibration at the chest or abdomen by sensing the mechanical vibration that the noise induces in the body. At the head, on the other hand, it was found that the vibratory sensation correlated comparably with the vibration acceleration level of the body surface vibration and the sound pressure level of the noise stimulus. This finding suggested that the mechanism of perception of vibration in the head is different from that of the perception of vibratory sensation in the chest and the abdomen.

scholarly journals Simulation and Experimental Investigation of the Stay Vane Channel Flow in a Reversible Pump Turbine at Off-Design Conditions

2017 ◽  
Vol 61 (2) ◽  
pp. 94 ◽  
Author(s):  
Sandro Erne ◽  
Gernot Edinger ◽  
Anton Maly ◽  
Christian Bauer
Keyword(s):  
Transient Flow ◽  
Guide Vane ◽  
Low Frequency ◽  
Rotating Stall ◽  
Design Flow ◽  
Flow State ◽  
Mean Flow ◽  
Load Range ◽  
Pump Turbine ◽  
Stall Inception

This work presents the assessment of the mean flow field and low frequency disturbances in the stay vane channel of a model pump turbine using transient numerical simulations and LDV-based measurements. The focus is laid on transient CFD simulations of characteristic flow states in the stay vane channel when operating at off-design conditions in pump mode. Experimental and numerical investigations obtained a shifting velocity distribution between the shroud and hub of the distributor when continuously increasing the discharge in the part-load range. Simulations captured the occurrence of this changing flow state in the stay vane channel reasonably well. A further increase of the discharge showed a uniformly redistributed mean flow of both hub and shroud side. Monitoring points and integral quantities from measurements and transient simulations were used to interpret the development of transient flow patterns in the stay vane channel at the operating point of strongest asymmetrical flow. During simulation and measurement, a dominant rotating stall inception was observed near the design flow of the pump turbine. At this point where the stall becomes severe, a high level of correlation between the signals of the upper and lower stalled flow in the stay vane channel was calculated. Further simulations for different guide vane positions predicted a strong influence of the guide vane position on the structure of rotating stall.

scholarly journals Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

2016 ◽  
Vol 23 (2) ◽  
pp. 309-316
Author(s):  
Marcin Lipiński ◽  
Przemysław Krehlik ◽  
Łukasz Śliwczyński ◽  
Łukasz Buczek ◽  
Jacek Kołodziej
Keyword(s):  
Fiber Optic ◽  
Data Transfer ◽  
Acoustic Noise ◽  
Mechanical Vibration ◽  
Low Frequency ◽  
Propagation Delay ◽  
Optical Signal ◽  
Testing Time ◽  
Optical Noise ◽  
Signal Phase

Abstract The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F) fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

The high enthalpy shock tunnel in Goettingen

1992 ◽  
Author(s):  
G. EITELBERG ◽  
T. MCINTYRE ◽  
W. BECK ◽  
J. LACEY
Keyword(s):  
Shock Tunnel ◽  
High Enthalpy ◽  
High Enthalpy Shock Tunnel
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