NUMERICAL MODELING OF A ROTARY VANE EXPANDER FOR A POWER CYCLE ON A PROPOSED LANDED MISSION TO VENUS

Open Access
Author:
Warmate, Tamuno Negiye
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Alexander S Rattner, Thesis Supervisor
  • Daniel Humberto Cortes Correales, Honors Advisor
Keywords:
  • Rotary Vane Expander
  • Venus Power Cycle
  • Numerical Modeling
Abstract:
Exploring Venus is a daunting task due to its extreme ambient conditions: a surface temperature exceeding 800K, high atmospheric pressure (about 90 bar), and high levels of atmospheric sulfur. This environment necessitates unconventional power generation approaches. Conventional power generating turbomachinery such as radial flow turbines, are expensive, require extreme rotation rates at planetary lander capacities, and are sensitive to two-phase flow (condensation). Rotary vane expanders can operate in mixed flow, operate at low rotational speed, and minimizes mechanical complexity, thereby reducing the likelihood of failure. The operating characteristics of a rotary vane expander are suitable for a small-scale system that can be incorporated into a lander-scale Rankine power system (100 W to 10kW). Additionally, traditional Rankine cycle working fluids (e.g., water/steam) would not be feasible as they would be supercritical at ambient conditions. The robustness of rotary vane expanders allows for the use of exotic working fluids such as vapor mercury. However, limited research has been done to explore the operational capabilities of using exotic working fluid in a rotary vane expander. Therefore, developing a computational model to estimate the performances and capabilities is the first critical step to determining the feasibility of the system. Two dynamic and adaptable models were developed to analyze the performance of rotary vane expanders in this application. The first model characterizes the expander at the individual working chamber and vane scale at a given operating condition. The second higher level model maps the power, torque, and efficiency over various operating conditions. The performance plots were comparable to those of similarly sized rotary vane expanders, but further validation is required.