Propellant Tank Level Sensing by EM Attenuation and Latency

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Solution Overview

Problem

Existing methods for measuring the level of a propellant tank, particularly for cryogenic media like liquid oxygen, are costly and inaccurate, and face limitations due to movement of the liquid propellant, especially in launch vehicles.

Innovation Solution

A method and apparatus using the degree of attenuation and latency of propagated power passing through the liquid propellant in a tank, measured by multiple reception antennas, to accurately determine the height level and flow of the propellant, incorporating a miniaturized transmission and reception antenna system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods (multiple thermometers, ultrasonic wave, or radio wave) are used to measure propellant tank level, then measurement capability is provided, but cost increases and measurement accuracy is limited

Engineering Contradiction:

Improvelevel measurement accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical measurement systems (multiple thermometers) and complex wave-based systems (ultrasonic/radio wave instruments) with an electromagnetic field-based measurement approach. By generating electromagnetic signals inside the tank and measuring their attenuation properties, the system achieves accurate level measurement without the mechanical complexity or high costs of conventional methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent measures level by detecting changes in electromagnetic signal attenuation parameters as the signal passes through different media (liquid propellant vs. gas). By monitoring the degree of attenuation and transfer time latency of the electromagnetic signal, the system determines the liquid level without requiring complex mechanical or wave-based measurement infrastructure.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If ultrasonic wave or radio wave methods are used for level measurement, then measurement is possible, but errors occur due to liquid propellant movement and instrument movement

Engineering Contradiction:

Improvelevel measurement accuracyVSAvoidmeasurement stability during vehicle movement

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The measurement system generates electromagnetic signals directly inside the propellant tank through a transmission antenna, eliminating the need for external instruments that could move relative to the tank. The system uses the tank's own electromagnetic environment for measurement, making it inherently more stable during vehicle movement and eliminating errors caused by relative motion between measurement instruments and the propellant.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If available instruments for cryogenic media are used, then measurement is possible, but cost increases and durability is limited

Engineering Contradiction:

Improvemeasurement capability for cryogenic mediaVSAvoiddurability in cryogenic environment

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces mechanical measurement instruments that have durability limitations in cryogenic environments with an electromagnetic field-based system. Electromagnetic signals can penetrate cryogenic media like liquid oxygen without being affected by extreme temperatures, providing both measurement capability and enhanced durability in cryogenic propellant tanks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Accurate and cost-effective measurement of propellant level and flow is achieved, even during vehicle movement, by considering both attenuation and latency, enabling precise fuel consumption estimation in launch vehicles.

Implementation Method 1

generating propagated power for level measurement at a specified generation intensity inside the propellant tank through a transmission antenna

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

receiving the propagated power for level measurement passing through the liquid fuel through a reception antenna

Methodology Applied

Scientific EffectElectromagnetic wave reception: Electromagnetic Induction

Implementation Method 3

calculating a degree of attenuation between the generation intensity and a reception intensity of the propagated power for level measurement

Methodology Applied

Scientific EffectElectromagnetic attenuation: Absorption (EM radiation)

Data Source

PatentUS12618705B2Method and apparatus for measuring level for calculating flow of propellant tank

Publication Date: 2026.05.05 KOREA AEROSPACE RES INST

AI summary

A method and apparatus for measuring a level for calculating a flow of a propellant tank are provided. The method of measuring a level for calculating a flow of a propellant tank includes, in response to an instruction to measure a level in a propellant tank storing a liquid fuel, generating propagated power for level measurement at a specified generation intensity inside the propellant tank through a transmission antenna, receiving the propagated power for level measurement passing through the liquid fuel through a reception antenna, calculating a degree of attenuation between the generation intensity and a reception intensity of the propagated power for level measurement, and measuring a height level of the liquid fuel by considering the degree of attenuation.