Rocket Engine Turbo Pump Constant Speed Control

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Solution Overview

Problem

Conventional turbo pump-type rocket engines face challenges in achieving high-speed responsiveness required for vertical takeoff and landing aircraft due to the moment of inertia of the rotary shaft, which limits thrust variability and responsiveness during landing and maneuvering.

Innovation Solution

The rocket engine design maintains a constant number of rotations of the rotary shaft regardless of the pump flow rate by optimizing the turbine efficiency curve and pump efficiency, allowing the turbo pump to operate within an equivalent region where the number of rotations remains constant, thereby reducing the reliance on moment of inertia for responsiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the moment of inertia of the turbo pump rotary shaft is reduced to improve responsiveness, then responsiveness is improved, but the structural integrity and durability of the rotary shaft deteriorate

Engineering Contradiction:
ImproveresponsivenessVSAvoidstructural integrity
Core Design Contradiction:
SpeedVSStrength

Solution Approach 1:

The patent applies composite materials to the rotary shaft structure, combining materials with different properties to achieve both low moment of inertia for high responsiveness and sufficient structural integrity for durability. The composite structure allows optimization of mass distribution while maintaining strength requirements.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and geometric parameters of the rotary shaft, such as cross-sectional shape, mass distribution, and structural configuration, to reduce moment of inertia while maintaining structural integrity. This includes optimizing the spatial arrangement of shaft components.

Inventive Principle:
Principle #35Parameter changes

2Speed

If the diameter of the rotor is decreased to reduce moment of inertia, then responsiveness is improved, but the pumping performance deteriorates

Engineering Contradiction:
ImproveresponsivenessVSAvoidpumping performance
Core Design Contradiction:
SpeedVSPower

Solution Approach 1:

The patent optimizes multiple parameters simultaneously, including rotor diameter, blade geometry, rotational speed, and chamber dimensions, to compensate for the reduced diameter effect. By adjusting these parameters in combination, the system maintains pumping performance while achieving lower moment of inertia.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic operation modes where the rotor can operate at variable rotational speeds and adjust its operational characteristics in real-time. This allows the system to maintain required pumping performance even with a smaller rotor diameter by optimizing the operational regime.

Inventive Principle:
Principle #15Dynamics

3Power

If the number of rotations is increased to maintain pumping performance after reducing rotor diameter, then pumping performance is maintained, but the centrifugal force increases beyond the decreasing effect on moment of inertia

Engineering Contradiction:
Improvepumping performanceVSAvoidcentrifugal force
Core Design Contradiction:
PowerVSForce

Solution Approach 1:

The patent optimizes the rotational speed parameter within an optimal range that balances centrifugal force effects with pumping performance requirements. Rather than continuously increasing rotations, the system finds an optimal operating point where performance is maximized without excessive centrifugal forces.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies different local structural characteristics to different parts of the rotor assembly, with reinforced sections in areas subjected to high centrifugal forces and optimized lighter sections in areas where responsiveness is critical, achieving local optimization of the force-performance tradeoff.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design enables high-speed response and thrust control without depending on the moment of inertia, significantly improving responsiveness from 0.2 Hz to 6 Hz, enhancing the engine's capability for vertical takeoff and landing operations.

Implementation Method 1

a turbine efficiency curve obtained on the basis of a conditional expression where the number of rotations of the rotary shaft is maintained constant

Methodology Applied
Scientific EffectTurbine: Turbine

Implementation Method 2

a pump efficiency curve where the number of rotations of the rotary shaft is maintained constant without depending on a pump flow rate

Methodology Applied
Scientific EffectPump: Pump

Data Source

PatentEP2476887B1Rocket engine system for realizing high-speed response
Publication Date: 2016.10.26 IHI CORP
  • EP2476887B1 patent drawingFigure 1
  • EP2476887B1 patent drawingFigure 2~3
  • EP2476887B1 patent drawingFigure 4A~4B

AI summary

Disclosed is a turbo pump in which a pump impeller is connected to one end of a rotary shaft and a turbine is connected to the other end of the rotary shaft. The turbo pump is designed such that an equivalent region, between a turbine efficiency curve obtained on the basis of a conditional expression where the number of rotations of the rotary shaft is maintained constant regardless of a pump flow rate and a turbine efficiency curve of an actual machine, becomes an operation region.