Blade fatigue, due to cavitation in rocket engine turbopumps, often triggers catastrophic system failures, costing insurers of space missions, launch vehicle operators and their customers billions of dollars every year. Next Planet Research’s Supercor VFI-689 / Vortex Force Impeller (VFI) System can potentially reduce rocket engine failures by optimizing launch vehicle performance and improving aerospace industry safety margins.

PROBLEM:

The combined effects of hydrodynamic cavitation and unbalanced rotordynamic forces, as well as the accumulation of turbopump operational efficiency losses can trigger a cascade of rocket motor propellant fuel feed subsystem and component malfunctions that can result in catastrophic failure. Rapidly dropping pressure in the turbopump’s volute, as the fluid mixes with the impeller produces vapor cavities or bubbles. Ultralow pressure causes the bubbles to collapse, producing a cycle of intense shockwaves. This cycle of implosions erodes the impeller blades, rotor hub and casing; exploiting areas where hydrodynamic, disk-friction and leakage losses occur. Fatigue failure of the impeller blades due to fluid dynamic instabilities, forces the supporting rotor platform into erratic oscillations causing undesired vibrations in the turbopump system and failing.

SOLUTION:

The VFI’s architecture consists of three interdependent structural components that work in concert to balance the pressure forces in the volute with the rotordynamic forces produced by the accelerating hub plate or rotor platform, vanes and flow channels.

The impeller’s hemispherical superstructure provides the VFI a system platform and attachment points for the substructure and metastructure complex, also providing suction surfaces and a secondary gravity damping feature.

The centrally located substructure contains the VFI’s thermoregulation system and primary gravity damping feature. The thermoregulation system helps maintain consistent temperatures, thus contributing to fluid dynamic stability inside the turbopump case. The gravity damping feature reduces vibrations caused by high-velocity rotation through maintaining the impeller’s weight and balance.

The spiraling metastructure flow channel complex are a series of sinusoidal quadrahelixes that wind about the superstructure’s axis of rotation and provides an inverted hydrofoil blade configuration. These quadrahelical metastructures contain and harness the flow field - optimizing suction, reducing vorticity, lowering hydrodynamic cavitation occurrences and delivering fluid propellant at lower RPM’s, thus requiring less power.

MANUFACTURABILITY:

Producing the VFI requires a subtractive manufacturing strategy, a multiaxis machining process capable of rendering complex geometric objects. The VFI reveals multiple freeform surfaces—it contains a network of quadrahelix flow channels spiraling about the axis of a hemisphere solid.

The most efficient approach to “finish machine” the VFI is to direct a 5-axis CNC machine tool in a spiral around the flow channel areas. Multiaxis machining saves time and eliminates mistakes that can be made with processes that require numerous setups.

OPPORTUNITY:

The Supercor 689 / VFI system is a world-class fuel feed solution that shows great promise for providing safer passage to space, saving launch systems manufacturers and their customers billions of dollars in unforeseen annual costs. Likewise, the Supercor system is a dual technology platform that provides both impeller and turbine solutions with numerous vertical market targets and high revenue generation potential.