P19102: Hybrid Rocket Engine
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

The team was able to finalize an engine design that would successfully integrative individual subsystems into a functioning engine that will successfully integrate into P19105's test stand.

The testing of the engine is currently in an unsure state. Originally, the engine was to be tested in a Bunker located just off campus. The secondary option was to propose and build an engine testing bunker. The bunker located off campus was deemed to be unfit for testing. The secondary option is still being worked out. If accepted, it is unlikely to be built in time for testing.

Design Freeze

Combustion Chamber

Functions
Acts as a pressure vessel (500 psi)
Contains combustion gases (5000 degrees F)
Combines oxidizer with solid fuel
Allows location for nozzle placement
Combustion Chamber Cross Section

Combustion Chamber Cross Section

Feed System

Feed System

Feed System

Pressurant Panel (N2)

Pressurant Panel (N2)

Propulsion Panel (N20)

Propulsion Panel (N20)

CAD version Panels

CAD version Panels

Tubing Assembly

Tubing Assembly

Ignition System

Overview
The proposed ignition method uses an off the shelf oxy-acetylene torch system, widely used for common welding applications. Due to the systems wide use, control and assembly will be trivial. The system will create a flame parallel to the injector plate which allows the wax fuel grain to be burned more evenly than was done in the past. Previous proposed designs (butane torch system) required a specific amount of oxygen within the combustion chamber that would just not exist. After determining the chamber would not contain enough oxygen in its volume, it was determined that oxygen must be pumped into the chamber. To minimize design time the off the shelf oxy-acetylene system was chosen.
Controllability
The system is comprised of 3 controllable components.
1) Oxygen solenoid
2) Acetylene solenoid
3) Spark generator

Using the proposed 'power distribution system', all components are controlled using simple 3.3v TTL.

Ignition System Flow Diagram

Ignition System Flow Diagram

Prototype
The system is pretty much the same as the detailed design. Some extra precautionary items have been added to the system, such as a spring loaded relieve valve.
Torch Prototype

Torch Prototype

Power Distribution

Power Distribution Proto-board

Power Distribution Proto-board

Overview
The power distribution system is constructed on a prototype board for easy circuit debugging and low cost assembly. The system uses three off the shelf "Pololu" Step-up power converters to create 3 distinct power rails. Ignition System, and Control system are all completely power by 4 Lithium Ion Batteries.
Power Distribution Proto-board

Power Distribution Proto-board

Voltage Rails
5V - Controller System Power
5V - High Voltage Spark Generator (Ignition System)
12V - Oxy-Acetylene Control Solenoids (Ignition System)
Power Distribution Schematic

Power Distribution Schematic

A small voltage level shifter was constructed to provide adequate power to the spark generator, while allowing the spark generator input power to be switched on/off by 3.3v TTL logic.

Communication System

The goal of the communication system is to create a line of contact between the engine system (including ignition, sensors, etc.) and a computer designated "mission control" that is located 300+ feet away.

(Photo of the control system with the orange circle) Communication between the engine controller and mission control occurs serially between a UART to an RS485.

Engine Controller

PCB Design Considerations
Places to mount both Teensy 3.6 boards
A place to mount a battery
Connectors for Pressure Transducers and Thermocouples
Amplifiers for the sensor signals
UART to RS-485 circuit
RS-485 Connector
Mission Control Needs

Mission Control Needs

Interface

Interface

Mission Controller

PCB Design Considerations
A place to mount Raspberry Pi Model 3 B
A place to mount a battery
UART to RS-485 circuit
RS-485 Connector
1 Ignition Key
1 Ignition Switch
4 Valve Switches
1 Switch with dedicated line to cut power to the Engine Controller
A way to handshake with the DAQ

Mission Control GUI Implementation - To be done using Python. The goal is to see data in real time, python allows for a flexible, easy to use way to accomplish this. The previous team's GUI was located and a large chunk of it will be recycled for this project.

Injector

The injector requires multiple designs to be created, tested, and analyzed in order to determine which geometry will best support our system. Originally the selection contained:

The Vortex/Swirl has determined to be slightly too complex. Moving forward, only the pintle and showerhead designs will be created and tested.

Pintle Design

Pintle Design

Showerhead Design

Showerhead Design

Prototyping, Engineering Analysis, Simulation

Iterative activities to demonstrate feasibility, including assumptions you made in your analyses or simulations. Have you completed sufficient analysis to ensure that your design will satisfy requirements? Have you included all usage scenarios in your modeling?

Drawings, Schematics, Flow Charts, Simulations

Describe your design in enough detail for someone else to recreate it. Have you included assembly plans and user manuals? Your team may want to create separate nodes and directories within the Detailed Design Documents directory for CAD, schematics, or software

Purpose

Bill of Material (BOM)

BOM

Test Plans

Purpose

Demonstrate objectively the degree to which the Engineering Requirements are satisfied

Instructions

  1. Instructions and EXAMPLE must be deleted before the first Detailed Design Review AND Identify an owner for this document.
  2. Complete test plans specifying the data to be collected, instrumentation to be used, testing procedures and personnel who will conduct the tests.
  3. Plans should use data collected to define the accuracy of models generated during feasibility analysis.
  4. Tests demonstrate that you met engineering requirements, which map back to your customer requirements. You should include a snapshot of your test plans here, but maintain the continuity of using your team's master requirements and testing document.
  5. If your team's testing will involve human subjects, you must review the RIT Human Subjects Research Office "Protecting Human Subjects" page for details on securing approval for work with human subjects

Inputs and Source

  1. Engineering Requirements.
  2. Test standards (e.g., ASTM). The RIT library maintains an infoguide with links to standards databases, many of which provide industry-standard test procedures for a variety of components and systems.
  3. Feasibility Models.

Outputs and Destination

  1. Report that summarized the degree to which Eng Reqs are satisfied.
  2. Assessment of accuracy of feasibility models.

Design and Flowcharts

This section should continue to be updated from your systems level design documentation.

Risk Assessment

Design Review Materials

Include links to:

Plans for next phase


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