Millisecond aerodynamic force measurement with side-jet model in theISL shock tunnel

Naumann, K. W.; Ende, H. van den; Mathieu, G.; George, A.

doi:10.2514/6.1992-3963

Cited by 8 publications

(10 citation statements)

References 1 publication

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“…Joarder and Jagadeesh (2004) implemented another free-floating technique in the HST2 facility, but this was limited to drag measurements. Naumann et al (1993) devised a method to allow for free-flight during the steady flow period whereby the model was mounted on a support that released just prior to the onset of the flow and tightened again shortly afterwards. Again, forces and moments were measured by means of accelerometers embedded in the model.…”

Section: Discussion Of Hypersonic Force-measurement Techniquesmentioning

confidence: 99%

Proximal bodies in hypersonic flow

2007

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The problem of proximal bodies in hypersonic flow is encountered in several important situations, both natural and man-made. The present work seeks to investigate one aspect of this problem by exploring the forces experienced by a secondary body when some part of it is within the shocked region created by a primary body travelling at hypersonic speeds.An analytical methodology based on the blast wave analogy is developed and used to predict the secondary force coefficients for simple geometries in both two and three dimensions. When the secondary body is entirely inside the primary shocked region, the nature of the lateral coefficient is found to depend strongly on the relative size of the two bodies. For two spheres, the methodology predicts that the secondary body will experience an exclusively attractive lateral force if the secondary diameter is larger then one-sixth the primary diameter. The analytical results are compared with numerical simulations carried out using the AMROC software and good agreement is obtained if an appropriate normalization for the lateral displacement is used.Results from a series of experiments in the T5 hypervelocity shock tunnel are also presented and compared with perfect-gas numerical simulations, again with good agreement. In order to model this situation experimentally, a new force-measurement technique for short-duration hypersonic facilities has been developed, and results from the validation experiments are included.Finally, the analytical methodology is used to model two physical situations. First, the entry of a binary asteroid system into the Earth's atmosphere is simulated. Seciv ond, a model for a fragmenting meteoroid in a planetary atmosphere is developed, and simulations are carried out to determine whether the secondary scatter patterns in the Sikhote-Alin crater field may be attributed to aerodynamic interactions between fragments rather than to secondary fragmentation. It is found that while aerodynamic interactions lead to increased secondary crater grouping, these groups do not exhibit the typically elliptical shape that we would expect secondary fragmentation to produce.

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Section: Discussion Of Hypersonic Force-measurement Techniquesmentioning

confidence: 99%

Proximal bodies in hypersonic flow

2007

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“…Joshi and Reddy, 1986) or to let the model fly freely during the test (e.g. Naumann et al, 1993). This eliminates the effect of a support mechanism decreasing the natural frequencies of the system.…”

Section: Introductionmentioning

confidence: 99%

Dynamic calibration of force balances for impulse hypersonic facilities

Mee

2003

Shock Waves

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Abstract. This paper analyzes different techniques for the calibration of force balances for use in shortduration impulse hypersonic facilities such as shock tunnels. The background to how deconvolution can be used to infer aerodynamic forces on models in impulse hypersonic wind tunnels is presented along with the theory behind the different calibration techniques. Four calibration techniques are applied to a singlecomponent stress-wave force balance. Experiments in the T4 shock tunnel using the balance demonstrate the suitability of the different calibrations for force measurements in an impulse facility. Cross checks between the calibration techniques are used to check their ranges of validity. It is shown that the impulse response derived from tests in which the model and force balance are suspended from a fine wire and the wire cut agree well with impulse responses derived from calibrations made using an impact hammer. The suitability of the balance for measuring dynamic forces is demonstrated by showing that the drag force on a model follows the history of Pitot pressure in the test section in the tunnel shots.

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“…The semi-free-flight technique (weakly restrained model support method) is one popular method for force measurement in shock tunnels. In the past few decades, this method has been modified by several researchers for several applications [5][6][7] . The present authors also have been doing basic studies using this 'semi-free-flight' technique for force measurement in HIEST.…”

Section: Force Measurements In Short Test Durationmentioning

confidence: 99%

Free-flight force measurement technique in shock tunnel

Tanno

Komuro

Sato

et al. 2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A novel force measurement technique has been developed at the impulsive facility HIEST, in which the test model is completely non-restrained for the duration of the test, so it experiences completely free-flight conditions for a period on the order of milliseconds. This technique was demonstrated with a three-component aerodynamic force measurement with a blunted cone of total length 318 mm and a total mass of 22 kg in hypervelocity test flow. A miniature modelonboard data-logger, which was a key technology for this technique, was also developed in order to store the measured data. The data-logger was designed to be small enough to be instrumented in test models, with an overall size of 100 mm x 100 mm x 70 mm, including batteries. Since the logger was designed to measure force and pressure, it includes six piezoelectric amplifiers and four piezoresistive amplifiers, as well as high-speed analogue-digital converters, which digitize the measured data with 16-bit resolution. The logger's sampling rate and sample size are 500 kHz and 400 ms, respectively. For the autonomous operation, the logger waits for a trigger signal (accelerometer output) and then starts to take measurements with arbitrary adjustable trigger threshold level and pre-trigger delay time. Measured data is stored to static memory for transfer to a PC via a USB interface after a wind tunnel test. To demonstrate the entire measurement system, wind tunnel experiments were conducted in HIEST. In the present wind tunnel test campaign, records of pressure, axial force, nominal force and pitching moment were obtained under conditions of H 0 = 4 MJ/kg, P 0 = 14 MPa. This demonstrated that the system worked correctly in the short test duration and harsh conditions typical of HIEST. Use of this data-logger allows the elimination of a large-diameter sting, ending concerns about the sting's interference with the base flow of the model, which could cause serious errors in measurement in wind tunnel tests.

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Millisecond aerodynamic force measurement with side-jet model in theISL shock tunnel

Cited by 8 publications

References 1 publication

Proximal bodies in hypersonic flow

Proximal bodies in hypersonic flow

Dynamic calibration of force balances for impulse hypersonic facilities

Free-flight force measurement technique in shock tunnel

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