Force Measurement in a Ludwieg Tube Tunnel

Juhany, Khalid A.; Darji, Anand P.

doi:10.2514/1.21014

Cited by 10 publications

(4 citation statements)

References 8 publications

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“…Additionally for sting mounted models, it is important that the dynamic response of the model and balance upon application of transient loads is shorter than the useful test time to allow for the measurement of quasi-static aerodynamic forces. This design criteria can often be difficult to achieve in short duration hypersonic facilities [8].…”

Section: Free-flight Technique and Scalingmentioning

confidence: 99%

“…The HDT has a very strong transient increase in total temperature during the first plateau of a shot due to unsteady compression in the plenum upstream of the nozzle throat and as all free-flight testing occurs during this first plateau, it results in a large uncertainty in total temperature. For more details on total temperature in the HDT see Herman et al [31]. With the information contained in Tables 3 and 4 it is possible to calculate the uncertainty in the aerodynamic coefficients.…”

Section: Acknowledgmentsmentioning

confidence: 99%

See 1 more Smart Citation

Free-Flight Aerodynamic Testing of the Skylon Space Plane

Hyslop¹,

Doherty²,

McGilvray³

et al. 2021

Journal of Spacecraft and Rockets

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The determination of aerodynamic coefficients for complex high speed vehicles still requires experimental measurement. This paper details the development of the free-flight measurement technique within the University of Oxford High Density Tunnel (HDT). In particular, a novel image processing technique is developed for calculating the position of the model from high speed video. This study focusses on the measurement of high Reynolds number experimental aerodynamic data for a subscale model of Reaction Engines' Skylon spaceplane. Testing was undertaken at a Mach 7 test condition replicating flight at an altitude of 63.5 km. Results for lift, drag and pitching moment coefficient were obtained over a range of angles of attack.

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Section: Free-flight Technique and Scalingmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

Free-Flight Aerodynamic Testing of the Skylon Space Plane

Hyslop¹,

Doherty²,

McGilvray³

et al. 2021

Journal of Spacecraft and Rockets

View full text Add to dashboard Cite

show abstract

“…In wind tunnel test projects, force testing is one of the most basic test items, mainly measuring the magnitude, position, and direction of the load on the aircraft during the test process. However, due to the short operating time of the pulse wind tunnel (on the order of one hundred milliseconds), in order to obtain more accurate aerodynamic loads and the thrust generated by the engine, the entire force measurement system needs to have a high frequency response and fast response speed [4][5][6][7]. At present, pulse wind tunnel force testing mainly relies on traditional strain balance force measurement technology, which measures the strain of the balance structure when the model is subjected to load using a Wheatstone bridge to obtain the force state of the model.…”

Section: Introductionmentioning

confidence: 99%

Design Method of Three-Component Optic Fiber Balance Based on Fabry–Perot Displacement Sensor

Xu,

Yu,

Zhang

2023

Sensors

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This article proposes a new type of three-component optic fiber balance based on Fabry–Perot displacement measurement technology based on the structure of the pulse wind tunnel balance. This paper systematically introduces the force measurement principle and design process of a three-component optic fiber balance and conducts relevant simulation analysis and experimental verification. The simulation results show that the Fabry–Perot sensor can achieve significant sensitivity to cavity length changes, and when used in existing balance structures, sensitivity gains can be achieved by changing the probe height without the need to modify the original structure of the balance. Finally, the feasibility of the design method was verified through calibration experiments: the optic fiber balance has high sensitivity and good linearity compared to simulation sensitivity, the error is less than 6%, and the calibration accuracy of each component is better than 0.13%, which is better than the existing traditional strain balance (0.37%). The pulse wind tunnel force measurement test has a short test time and a large model mass, and the balance needs to have a large stiffness to meet the short-term force measurement requirements. The introduction of more sensitive optic fiber balance force measurement technology is expected to solve the contradiction between the stiffness and sensitivity of force measurement systems.

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“…Furthermore, in short duration hypersonic facilities with test of times in the order of milliseconds to tens of milliseconds, stress waves within the model and supporting structure do not reach equilibrium making it difficult to measure quasi-static aerodynamic forces. Therefore, it is important that the dynamic response of the sting-model system is shorter than the available test time which is often difficult to achieve in hypersonic facilities [3]. Mee et al [4] developed a rigid 3 component force balance for measurements in shock tunnels using the stress wave technique but accurate forces were still difficult to obtain, even when using advanced deconvolution techniques.…”

Section: Introductionmentioning

confidence: 99%

Free-Flight Aerodynamic Testing of a 7 Degree Half-Angle Cone

Hyslop

McGilvray

Doherty

2022

AIAA SCITECH 2022 Forum

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Free-flight experiments have been conducted in the University of Oxford High Density tunnel, a heated Ludwieg tube, with a 7 degree half angle cone. The goal of the investigation was to examine the potential for the free-flight experimental method to measure purely static aerodynamic coefficients. The tests were conducted at Mach 6 and 7 conditions representative of a hypersonic vehicle's trajectory at 35 km altitude. The model was designed so that the centre of gravity of the model could be fine-tuned to be at the same position as the centre of pressure, hence minimising the static margin of the model. This resulted in a model that exhibited minimal pitch during a test, thus providing high-quality static aerodynamic data for an unconstrained model. Non-intrusive techniques such as image tracking and on-board inertial measurement units were used to determine accelerations to ultimately determine the aerodynamic forces acting on the cone. Results for lift, drag and pitching moment coefficients were obtained over a range of angles of attack and compared with predictions from a hypersonic panel method code. The experimental and numerical data sets agreed well over the range of angles of attack with the experimental uncertainties remaining below 2.55 % for all coefficients.

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Force Measurement in a Ludwieg Tube Tunnel

Cited by 10 publications

References 8 publications

Free-Flight Aerodynamic Testing of the Skylon Space Plane

Free-Flight Aerodynamic Testing of the Skylon Space Plane

Design Method of Three-Component Optic Fiber Balance Based on Fabry–Perot Displacement Sensor

Free-Flight Aerodynamic Testing of a 7 Degree Half-Angle Cone

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