Integral Composite Rocket Motor Dome Nozzle Structure

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Solution Overview

Problem

Conventional rocket motor nozzles face challenges with thermal performance, structural weight, and fabrication cost due to multiple insulation layers and bond joints that can fail under extreme heat loads, particularly in pulsed rocket motors, which require maintaining structural integrity during multiple burn periods.

Innovation Solution

A composite dome and nozzle structure is fabricated using a single high-temperature resin system with different fiber layers for structural strength, thermal ablation, and insulation, eliminating the need for multiple bond joints by integrating the dome and nozzle as a single composite component with a common resin system, reducing thermal stress and fabrication complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple insulation layers with different TCEs are used between carbon-carbon insulation and metal shell, then thermal expansion compatibility is improved, but bond joint reliability deteriorates under extreme heat loads

Engineering Contradiction:
Improvethermal expansion compatibilityVSAvoidbond joint integrity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges the dome and nozzle into a single integral composite structure made of high-temperature resin and fiber layers, eliminating the need for separate insulation layers and bond joints between dissimilar materials. This integration resolves the contradiction by removing the interface where thermal expansion incompatibility causes bond failure, while maintaining thermal protection through the composite material design itself.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention uses a composite material system consisting of high-temperature resin combined with specific fiber layers (such as carbon fibers, ceramic fibers, or ablative fibers) that provide both thermal insulation and structural integrity. This composite approach allows the material itself to handle thermal expansion stresses without requiring multiple intermediate layers, thus maintaining bond joint reliability while achieving thermal compatibility.

Inventive Principle:
Principle #40Composite materials

2Reliability

If multiple laminate interfaces with differing materials are used in traditional rocket motor aft bodies, then thermal shock capability is achieved, but structural weight and fabrication complexity increase

Engineering Contradiction:
Improvethermal shock capabilityVSAvoidfabrication complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functional layers (structural support, thermal insulation, and thermal shock resistance) into a single integral composite dome/nozzle structure. The high-temperature resin matrix combined with strategically oriented fiber layers provides all necessary functions in one monolithic component, eliminating the need for multiple separate laminate interfaces and reducing fabrication complexity while maintaining thermal shock capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention employs a sophisticated composite material system where the high-temperature resin matrix is reinforced with fiber layers having specific properties (carbon fibers for strength, ceramic fibers for insulation, ablative fibers for heat protection). This multi-functional composite material achieves thermal shock resistance without requiring assembly of multiple separate components, thereby reducing fabrication complexity.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If multiple bond joints are used in conventional dome/nozzle assemblies, then assembly flexibility is improved, but structural integrity deteriorates under repeated thermal cycling

Engineering Contradiction:
Improveassembly flexibilityVSAvoidstructural integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent merges the dome and nozzle into a single integral structure formed as one piece through composite manufacturing processes. This eliminates all bond joints between the dome and nozzle, removing the weak points that would fail under repeated thermal cycling, while still allowing for manufacturing flexibility through modular fiber layering and curing processes.

Inventive Principle:
Principle #5Merging (Combining)

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

The integrated composite structure enhances thermal performance, reduces structural weight, and lowers production costs by simplifying fabrication and eliminating redundancy, while maintaining robust structural integrity and tighter angular assembly tolerances, improving the overall efficiency and range of rocket motors.

Implementation Method 1

a single high temperature resin system with different fibers for airframe continuity, structural strength, and thermal ablation characteristics

Methodology Applied
Scientific EffectThermal ablation: Ablation

Implementation Method 2

different fibers for airframe continuity, structural strength, and thermal ablation characteristics

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2155546B1Integral composite rocket motor dome/nozzle structure
Publication Date: 2018.11.28 RAYTHEON CO
  • EP2155546B1 patent drawingFigure 1~2
  • EP2155546B1 patent drawingFigure 3
  • EP2155546B1 patent drawingFigure 4a~4b

AI summary

An integral composite rocket motor nozzle (100). The novel nozzle (100) includes a first layer of a first reinforcement material (110), a second layer of a second reinforcement material (112), and a common matrix material (116) surrounding the first and second reinforcement materials (110, 112) such that the reinforcement materials (110, 112) and matrix material (116) form a single integral composite structure. In an illustrative embodiment, the first reinforcement material (110) includes graphite fibers for providing structural support and the second reinforcement material (112) includes glass or quartz fibers for providing thermal insulation on a first side of the first layer (110). The nozzle (100) may also include a third layer of a third reinforcement material (114) for providing thermal insulation on a second side of the first layer (110). In a preferred embodiment, the first layer (110) is shaped to form an integrated dome and nozzle structure.