Rotorcraft Rotor Speed Regulation Under Icing Conditions

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Solution Overview

Problem

Rotorcraft performance is significantly affected by icing conditions, leading to increased drag and reduced aerodynamic efficiency due to the formation of rime or ice on blades, particularly in critical temperature domains.

Innovation Solution

A method to regulate the drive speed of rotorcraft rotors by adjusting the NR speed based on ambient temperature ranges within the critical temperature domain, decreasing speed in low temperature icing ranges to reduce ice formation and increasing speed in high temperature icing ranges to prevent ice accumulation, utilizing on-board instrumentation and control units to calculate and apply appropriate NR setpoints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotor speed is maintained at nominal value under icing conditions, then the rotorcraft maintains optimal lift and propulsion performance, but ice accumulation on blades increases drag and deteriorates aerodynamic characteristics

Engineering Contradiction:

Improverotorcraft performanceVSAvoidice accumulation on blades

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the rotor speed variable rather than fixed. The control system continuously adjusts the rotor speed based on detected icing conditions, transitioning from a static nominal speed to a dynamic adaptive speed that responds to changing environmental conditions, thereby preventing ice accumulation while maintaining performance

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of rotor speed in response to icing conditions. By detecting temperature and icing status, the system modifies the rotor speed parameter from its nominal value to a corrected value that prevents ice formation, directly addressing the harmful effect of ice accumulation

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the rotor speed is decreased to prevent ice formation, then ice accumulation is reduced, but rotorcraft lift and propulsion performance deteriorate

Engineering Contradiction:

Improveice formation on bladesVSAvoidrotorcraft lift and propulsion

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent implements feedback control by using on-board instrumentation to detect icing conditions and feed this information back to the control system. The control system then adjusts rotor speed based on this feedback, creating a closed-loop system that prevents ice formation while minimizing performance loss through intelligent, condition-based adjustments

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-service by using its own instrumentation and control capabilities to detect and respond to icing conditions autonomously. The rotorcraft monitors its own operational state and automatically adjusts rotor speed without external intervention, maintaining performance while preventing ice accumulation

Inventive Principle:

Principle #25Self-service

3Measurement precision

If on-board instrumentation is used to detect icing conditions, then accurate identification of critical temperature domains is achieved, but device complexity increases

Engineering Contradiction:

Improveicing condition detection accuracyVSAvoidon-board instrumentation system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by designing the control system to perform multiple functions: it detects icing conditions, identifies critical temperature domains, calculates corrected rotor speed, and controls rotor operation all through a single integrated control system. This multi-functionality reduces overall system complexity despite the need for precise measurements

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach limits the formation of rime and ice on rotor blades, reducing drag and maintaining performance by optimizing blade surface temperature and aerodynamic shape, thereby attenuating the overall loss of rotor performance under icing conditions.

Implementation Method 1

the blades being heated as a result of the impact of supercooled drops of water contained in the ambient outside air striking their leading edges

Methodology Applied

Scientific EffectImpact heating: Impact Force

Implementation Method 2

A method to regulate the drive speed of rotorcraft rotors by adjusting the NR speed based on ambient temperature ranges within the critical temperature domain

Methodology Applied

Scientific EffectSpeed regulation:

Data Source

PatentUS9580182B2Method of regulating the speed at which a rotorcraft rotor is driven under icing conditions

Publication Date: 2017.02.28 EUROCOPTER FRANCE SA

AI summary

A method of regulating the NR speed at which the rotor of a rotorcraft is driven in rotation. On detecting that the rotorcraft is flying under icing conditions in a previously identified critical temperature domain (Dct), the NR speed is either decreased in the situation where the ambient outside air temperature (OAT) lies in a low temperature icing range (Ptb) of the critical temperature domain (Dct), or else it is increased in the situation where the ambient outside air temperature (OAT) lies within a high temperature icing range (Pth) of the critical temperature domain (Dct).