Force Measurement Techniques for Hypersonic Flows in Shock Tunnels

Sahoo, Niranjan; Reddy, K. P. J.

doi:10.1260/1759-3107.1.1.31

Cited by 10 publications

(3 citation statements)

References 47 publications

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“…This process resembles the practice followed in Sahoo and Reddy. 35 But while opting multipoint training strategy, all the impulse forces and their responses are accounted for either AOA arrangements. After training, recovery of forces is obtained for 0° AOA.…”

Section: Resultsmentioning

confidence: 99%

A comparison of accelerometer and piezofilm-based force balances for hypersonic shock tunnels

Nanda

Kulkarni

Sahoo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part G:

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A blunt double-cone model, equipped with a three-component accelerometer or piezofilm-based force balance system, is tested in the IITB-Shock Tunnel at 0 º and 10 º angle of inclinations during force measurement experiments. Conventional accelerometer force balance theory and soft computing-based adaptive neuro fuzzy inference system have been adopted to recover the axial and normal forces. In order to arrive at the time varying forces, these balances are calibrated using impulse hammer tests at single or multiple points. Necessity of multipoint calibration has also been demonstrated during recovery of forces for both the balances. Genetic algorithm in conjunction with adaptive neuro fuzzy inference system has been implemented herein to train the system for force prediction. Encouraging agreement has been noted between the predictions made using accelerometer force balance theory and adaptive neuro fuzzy inference system-based recovery of forces from accelerometer and piezofilm balances. Thus, present studies not only provide the methodology for calibration and implementation of piezofilm based force measurement, but also recommend its usage in short duration impulse facilities.

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Section: Resultsmentioning

confidence: 99%

A comparison of accelerometer and piezofilm-based force balances for hypersonic shock tunnels

Nanda

Kulkarni

Sahoo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Choice of brass as material for the stress bar is due to the fact that the stress wave propagation takes place at lower acoustic speeds. Thus, it enables to receive the response for longer duration (Sahoo and Reddy 2010). Initially, finite element (FE) simulations are carried out in order to arrive at an optimum location of strain gauge position where higher magnitude of the strain can be expected.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Apt strain measurement technique for impulsive loading applications

Nanda

Kulkarni

Sahoo

2017

Meas. Sci. Technol.

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The necessity of precise measurement of strain time history for impulsive loading applications has been addressed in the present investigation. Finite element modeling is initially carried out for a hemispherical test model and stress bar assembly to arrive at an appropriate location for strain measurement. In dynamic calibration experiments, strain measurements are performed using two wire and three wire quarter bride arrangements along with half bridge circuit. Usefulness of these arrangements has been verified by analyzing strain signals in time and frequency domains. Comparison of recovered force time histories proved that the half bridge circuit is the most suitable for such applications. Actual shock tube testing of the instrumented hemispherical test model confirmed the applicability of half bridge circuit for short duration strain measurements.

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“…This makes it very difficult to measure the aerodynamic forces. Classical strain gauge balance is used in our tests, though some other kind of balances such as accelerometer balance and stress-wave force balance system [12] might be feasible. In the beginning of the wind tunnel test, a sudden aerodynamic loading will excite the vibration of the model-balance-sting system, which can distort the balance signal sensed by strain gauges in force measurements.…”

Section: Introductionmentioning

confidence: 99%

Wave system fitting: A new method for force measurements in shock tunnels with long test duration

Luo

Wang

Chun

et al. 2015

Mechanical Systems and Signal Processing

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a b s t r a c tForce measurements in shock tunnels are difficult due to the existence of vibrations excited by a sudden aerodynamic loading. Accelerometer inertia compensation could reduce its negative effect to some extent, but has inherent problems. A new signal decomposition method, wave system fitting (WSF), is proposed to remove vibration waves of low frequency. The WSF is accelerometer-free. It decomposes the balance signal and can separate vibration waves without the influence on the DC component, and it does work no matter the cycle of the sample signal is complete or not. As a standard signal postprocessing tool in JF-12, the application results show that it works reliably with high accuracy, and it can also explain puzzling signals encountered in JF-12. WSF method is especially useful and irreplaceable whenever only a few cycles of a periodic signal could be obtained, as is usual for shock tunnels.

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Force Measurement Techniques for Hypersonic Flows in Shock Tunnels

Cited by 10 publications

References 47 publications

A comparison of accelerometer and piezofilm-based force balances for hypersonic shock tunnels

A comparison of accelerometer and piezofilm-based force balances for hypersonic shock tunnels

Apt strain measurement technique for impulsive loading applications

Wave system fitting: A new method for force measurements in shock tunnels with long test duration

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