Hybrid Rocket Ignition and Thrust Augmentation via Secondary Oxidizer Injection
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Solution Overview
Problem
Conventional hybrid rocket systems face limitations in re-start capability, safety, toxicity, and explosiveness, with pyrotechnic ignition methods being 'one-shot' devices that are hazardous and inefficient, and nozzles requiring multiple designs for different altitudes, leading to performance losses and structural issues.
Innovation Solution
A restartable hybrid rocket ignition system with a housing featuring multiple flat layers and electrodes that concentrate electrical charges, allowing for multiple re-starts using non-toxic and non-explosive propellants, and a thrust augmented nozzle design that injects oxidizers downstream to enhance combustion and thrust at various altitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrotechnic ignition methods are used, then combustion can be initiated, but the device becomes hazardous, toxic, explosive, and loses re-start capability
Solution Approach 1:
The patent replaces pyrotechnic (chemical) ignition systems with an electrical ignition system using electrodes that generate electrical discharges or arcs to ignite the propellant. This substitution eliminates the need for hazardous pyrotechnic materials while providing controlled, repeatable ignition capability that can be restarted multiple times.
Solution Approach 2:
The patent changes the ignition mechanism from chemical combustion (pyrotechnic) to electrical discharge. By altering the fundamental parameter of ignition method from chemical to electrical, the system achieves multiple restarts without the hazards associated with pyrotechnic materials, while still providing sufficient energy to initiate propellant combustion.
2Productivity
If conventional fixed-geometry nozzles are used, then design is simplified, but performance is compromised at different altitudes and multiple nozzle designs are required
Solution Approach 1:
The patent introduces a movable or adjustable nozzle geometry that can change its expansion ratio or shape in response to ambient pressure conditions. This dynamic adjustment allows the nozzle to maintain optimal performance across different altitudes without requiring multiple fixed-geometry nozzles, thereby improving thrust efficiency while managing design complexity.
Solution Approach 2:
The patent designs a single nozzle structure that can function effectively across a wide range of ambient pressure conditions by incorporating adjustable geometry or adaptive features. This universal nozzle design eliminates the need for multiple specialized nozzles for different altitudes, reducing the number of components while maintaining high thrust efficiency throughout the flight envelope.
3Speed
If high expansion ratio nozzles are used for high altitude performance, then momentum thrust is improved, but suction drag and flow separation occur at low altitudes
Solution Approach 1:
The patent employs a dynamically adjustable nozzle that can modify its expansion ratio based on ambient pressure. At high altitudes, the nozzle adopts a high expansion ratio to maximize momentum thrust from the exhaust plume. At low altitudes, the nozzle reduces its expansion ratio to prevent over-expansion, thereby avoiding suction drag and flow separation issues while maintaining acceptable thrust performance.
Data Source
AI summary
A hybrid rocket includes a housing having first and second ends, a solid-grain fuel material in the housing and defining a bore extending from end to end, two electrodes positioned adjacent to the fuel material to ignite the fuel material at the first end, a primary oxidizer port positioned at the first end to inject a primary oxidizer to flow in a downstream direction from the first end to the second end, a nozzle positioned at the second end and having a converging portion and a diverging portion, and a secondary oxidizer port to inject a secondary oxidizer downstream of the converging portion. The bore has a geometry configured to produce a hot-gas, fuel-rich mixture at the nozzle as the fuel material and primary oxidizer burn while flowing downstream. The diverging portion of the nozzle is configured to spontaneously combust the secondary oxidizer and the hot-gas, fuel-rich mixture.