Determination of Aerodynamic Coefficients from Shock Tunnel Free Flight Trajectories

Wey, Pierre; Seiler, F.; Srulijes, J.; Bastide, Myriam; Martinez, Bastien; Gnemmi, Patrick

doi:10.2514/6.2012-3321

Cited by 15 publications

(5 citation statements)

References 3 publications

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“…For the SWT, the logarithmic size factor was from 0.17 to 1.43 g/mm, which indicates that heavy test models could be used. Since the strain gauge-based technique SWT obtained the drag from the structural deformation of the test model-support system, it was not necessary to [6,10,11,[48][49][50]; the MST data obtained from Refs. [7,12,13,22,24,51,52]; the SWT data obtained from Refs.…”

Section: Comparison Of the Test Environment Between Drag Measurement ...mentioning

confidence: 99%

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Assessment of drag measurement techniques in a shock tunnel

et al. 2022

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Three force measurement techniques in a shock tunnel, the free-flight, movable-support force balance, and stress-wave force balance techniques were employed, and each technique’s characteristics were assessed. For each force measurement technique, the system setup, data processing method, measurement uncertainties, and applied range of the test model size-flow establishment time were described in detail and compared. For a comparison and discussion, the drag coefficients of a circular pointed cone model with a semi-angle of 18.4° at a nominal freestream Mach number of 6 were measured. As a result, three force measurement techniques yield similar drag coefficients. However, the measurement uncertainties were increased in the order of the free-flight, the stress-wave force balance, and the movable-support force balance techniques. The main causes of the measurement uncertainties were the corner detection uncertainties for the free-flight techniques, and the propagation of the internal or external vibrations for the movable-support and stress-wave force balance techniques. To estimate the appropriate range of the test model size and flow establishment time for each technique’s application, the force measurement systems of the present work and the available literature were compared. As a result of comparative discussion, force measurement environments that can be advantageous for each technique are suggested.

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Section: Comparison Of the Test Environment Between Drag Measurement ...mentioning

confidence: 99%

“…Range of size factor and flow establishment time for each technique. The FFT data obtained from Refs [6,10,11,[48][49][50][7,12,13,22,24,51,52]…”

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confidence: 99%

Assessment of drag measurement techniques in a shock tunnel

et al. 2022

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“…The higher the natural frequencies are, the better the justification for the neglected acceleration compensation. For these test conditions, many researchers have proposed several special balances to measure the aerodynamic forces in impulse facilities-i.e., the accelerometer balance [5][6][7], the stress-wave force balance [8][9][10], the free-flight measurement technique [11][12][13][14][15], the compensated balance [16], and the impulse-type strain gauge balance (SGB) [17,18]. Owing to the very short test time, however, mature technology has not been developed for the force measurement in a shock tunnel.…”

Section: Introductionmentioning

confidence: 99%

Intelligent Force-Measurement System Use in Shock Tunnel

Wang

Jiang

2020

Sensors

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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.

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“…2 The higher the natural frequencies, the better the justification for the neglected acceleration compensation. For such test conditions, many researchers proposed several special balances to measure the aerodynamic forces in the impulse facilities, that is, accelerometer balance, [5][6][7] stress-wave force balance, [8][9][10] free-flight measurement technique, [11][12][13][14][15][16] and compensated balance. 17 Owing to the very short test time, however, the mature technology was undeveloped for the force measurements in a shock tunnel.…”

Section: Introductionmentioning

confidence: 99%

A gasdynamic gun driven by gaseous detonation

Chen

Zhang

et al. 2016

Review of Scientific Instruments

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Force tests were conducted at the long-duration-test shock tunnel JF12, which has been designed and built in the Institute of Mechanics, Chinese Academy of Sciences. The performance tests demonstrated that this facility is capable of reproducing a flow of dry air at Mach numbers from 5 to 9 at more than 100 ms test duration. Therefore, the traditional internal strain-gauge balance was considered for the force tests use in this large impulse facility. However, when the force tests are conducted in a shock tunnel, the inertial forces lead to low-frequency vibrations of the test model and its motion cannot be addressed through digital filtering because a sufficient number of cycles cannot be found during a shock tunnel run. The post-processing of the balance signal thus becomes extremely difficult when an averaging method is employed. Therefore, the force measurement encounters many problems in an impulse facility, particularly for large and heavy models. The objective of the present study is to develop pulse-type sting balance by using a strain-gauge sensor that can be applied in the force measurement of 100 ms test time, especially for the force test of the large-scale model. Different structures of the S-series (i.e., sting shaped balances) strain-gauge balance are proposed and designed, and the measuring elements are further optimized to overcome the difficulties encountered during the measurement of aerodynamic force in a shock tunnel. In addition, the force tests were conducted using two large-scale test models in JF12 and the S-series strain-gauge balances show good performance in the force measurements during the 100 ms test time.

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Determination of Aerodynamic Coefficients from Shock Tunnel Free Flight Trajectories

Cited by 15 publications

References 3 publications

Assessment of drag measurement techniques in a shock tunnel

Assessment of drag measurement techniques in a shock tunnel

Intelligent Force-Measurement System Use in Shock Tunnel

A gasdynamic gun driven by gaseous detonation

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