Engineering topics

Rao, G.

Publications and source records attributed to Rao, G..

6 records

NASA NTRS2006

The Long-Term Performance of Small-Cell Batteries Without Cell-Balancing Electronics

Tests approx.8 yrs ago showed Sony HC do not imbalance. AEA developed a theory (ESPC 2002): a) Self-discharge (SD) decreases with state-of-charge (SOC); b) Cells diverge to a state of dynamic equilibrium; c) Equilibrium spread depends on cell SD uniformity. Balancing model verified against test data. Short-term measures of SD difficult in Sony cells and very small values, depends on technique. Long-term evidence supports lower SD at low SD. Battery testing best proof of performance, typically mission specific tests.

Pearson, C.↗

NASA NTRS2006

Performance of AEA 80 Ah Battery Under GEO Profile

To date completed three Solar Dynamic Observatory SDO real-time eclipse seasons. Sony 18650HC has a low rate of capacity fade under GEO cycling regime. Real time test results correlate with accelerated GEO lifetest data and AEA capacity fade prediction tool. This data, together with other AEA test data, justify the SDO Project decision to baseline Lithium-Ion chemistry for the spacecraft battery.

Russel, N.↗

NASA NTRS2004

Design, Build and Qualification of the ST-5 Nanosat Batteries

This viewgraph presentation provides information about battery configuration, GSFC performance requirements, unique ST-5 mission requirements, battery design, materials, and testing.

Curzon, D.↗

NASA NTRS2004

Performance of AEA 80 Ah Battery under GEO Profiles

This viewgraph presentation is divided into the following sections: 1) AEA Geosynchronous Earth Orbit (GEO) Life Testing; 2) AEA/Goddard Space Flight Center (GSFC) 20 Ah Battery; 3) AEA/GSFC 80 Ah Battery; 4) Solar Dynamic Observatory (SDO) Life Test; 5) Test Results; 6) Correlation; 7) Conclusions.

Russel, N.↗

NASA NTRS2003

Design, Build and Qualification of 28 Volt Lithium-Ion battery

Contents include the following: 1. GSFC performance specifications requirements. 2. AEA philosophy: battery configuration. 3. AEA battery design: SONY cell, cell screening, 20Ah and 60Ah. 4. Testing: 20Ah battery qualification (environmental); 60Ah battery LEO life cycle. 5. Conclusion.: summary and lessons learned.

Curzon, D.↗

NASA NTRS1987

Reducing Fatigue in a Rotary Flowmeter

Redesign of vanes straightening flow of liquid in rotary flowmeter increase fatigue lives of vanes and rotor. Purpose of vanes to eliminate turbulence so proportionality between flow and rotor speed constant. Nonuniform but symmetrical, new spacing of straightener vanes prevents flow wake from strongly interacting with rotor blades. At same time, vanes ensure accurate flow-rate measurement.

Rao, G.↗