| 1. |
- Sundberg, Torbjörn, et al.
(författare)
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Small recoverable payload for deployable sounding rocket experiments
- 2009
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Ingår i: Proceedings of the 19th Esa Symposium on European Rocket and Balloon Programmes and Related Research. - 9789292212353 ; , s. 281-284
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Konferensbidrag (refereegranskat)abstract
- We present a design of a small payload for deployment from sounding rockets. The payload is intended for measurements in the ionosphere and the acquired data is stored onboard. For a secure recovery of the data and possible re-use of the payload, an inflatable structure is deployed during the payload descent. This reduces the payload speed and protects it from ground impact. On the ground, a localization system is activated, sending the payload position via a satellite link, and providing a radio beacon signal. The proposed small payload will allow high time resolution multipoint measurements in the ionosphere with small separation distances, thus allowing to address a number of unresolved questions in the field.
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| 2. |
- Wu, YH, et al.
(författare)
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Numerical and experimental investigations of closure of an emergency bulkhead gate
- 2015
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Konferensbidrag (refereegranskat)abstract
- The design of hydraulic gates is crucial for safely operating a hydropower dam. An emergency gate is especially important as it protects structures or turbines situated downstream. In this study, both numerical and experimental investigations were performed of an emergency bulkhead gate closure. The gate has a size of 4.978 m (w) by 6.166 m (h) and a thickness of 0.94 m and is subjected to a water head of 80.8 m and a flow rate of 207 m3/s. In an earlier stage, a 1:18 scale model was constructed. The CFD simulations were then made using the RNG k−ε turbulence model and Volume of Fluid method (VOF). A moving dynamic mesh was adopted to follow the gate movement. The goal was to extract the pressure distribution around the gate, subsequently to obtain the hydrodynamic forces acting on the gate and to analyze the flow pattern. The CFD model was validated against the experimental data. The closing speed of the gate and its bottom edge angle were examined in order to reduce the down-pull force and to avoid undesirable flow phenomena. It was found that to lower the gate speed to 8.1 m/min would have a positive effect. The gate would close slower, with reduced forces and less induced vibrations. To change the gate bottom edge angle from 9° to 20-30°, would considerably reduce gate vibrations.
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