Drift-flux analysis of two-phase flow in microgravity /
As NASA programs such as the International Space Station, the Space Shuttle, the Space Nuclear Power Initiative, and other future spacecraft become more demanding, two-phase (gas-liquid) systems for advanced life support and thermal management are highly advantageous over single-phase systems. Two-...
| Main Author: | |
|---|---|
| Format: | Thesis eBook |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2004.
|
| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Summary: | As NASA programs such as the International Space Station, the Space Shuttle, the Space Nuclear Power Initiative, and other future spacecraft become more demanding, two-phase (gas-liquid) systems for advanced life support and thermal management are highly advantageous over single-phase systems. Two-phase fluid loops provide significant thermal transport advantages over their single-phase counterparts and are able to carry more energy per unit mass than single-phase systems. They are also able to transport more energy per unit pumping power than single-phase systems. These two advantages alone offer great reductions in both mass and volume, which are two primary design parameters for space-based systems. Unfortunately, the ability to predict two-phase phenomena such as flow regime transitions and void fraction at microgravity conditions is greatly limited and its development is still in its infancy. A Texas A&M University two-phase flow loop was tested aboard NASA's KC-135 aircraft to collect two-phase microgravity data for dichlorodifluoromethane (R-12). A wide variety of flow rates were tested and many different flow regimes were observed. Data produced by the two-phase microgravity experiment were analyzed in accordance with the drift-flux model to calculate the distribution parameter, C₀, and the drift-velocity, V[gj], of the two-phase mixture. The C₀and V[gj] found for each flow regime were compared with other microgravity and a one-g upflow data. The C₀ for the slug flow regime was greater than that of the transition and annular flow regimes respectively for the microgravity data and correlated well with other R-12 microgravity data for the slug flow regime. The V[gj] for slug flow was found to be negative, which was unexpected, but the drift velocities for the transition and annular flow regimes provided expected results. The V[gj] for the annular flow regime in microgravity was less than that of the one-g upflow system due to the lower superficial velocities required in microgravity. Similarly, the C₀ for the R-12 microgravity data was higher than for a one-g upflow system due to its lower void fraction. A common C₀ and V[gj] can be used to predict void fraction for the transition and annular flow regimes for R-12 for the same pipe diameter and operating conditions. |
|---|---|
| Item Description: | "Major subject: Nuclear Engineering". Vita. |
| Physical Description: | xi, 58 leaves : illustrations ; 28 cm. Also available online. Issued also on microfiche from Lange Micrographics. |
| Bibliography: | Includes bibliographical references (leaves 53-55). |