The Combustion Integrated Rack (CIR), located in the US Laboratory Module (Destiny), enables investigators to perform combustion research to understand the fundamentals of the combustion process, understand fire safety, and methods for suppression of fires in space. The CIR’s main feature is a 100-liter combustion chamber to provide the necessary safety features necessary for the various combustion investigations and is the only rack on ISS dedicated to combustion experimentation. Developed by NASA’s Glenn Research Center, the CIR was launched to the International Space Station (ISS) in November 2008 by the Space Shuttle (STS-126).
The CIR provides up to 90% of the required hardware to perform a majority of future microgravity combustion experiments on board the ISS. The remaining 10% of the hardware (fuel, igniters, etc.) is provided by the specific investigation teams. A significant amount of diagnostic hardware is designed for many of the planned experiments. The CIR accommodates experiments that address critical needs in the areas of spacecraft fire safety (i.e., fire prevention, detection and suppression), fundamental understanding of the combustion process, flame spread, soot production, material selection, power generation, and incineration of solid wastes.
|CIR MDCA Hardware Overview||CIR Rack Installation|
The Combustion Integrated Rack (CIR) features a 100-liter combustion chamber for performing the combustion experiments, a fluid/oxidizer management assembly to condition gases for the experiments, and easily reconfigurable diagnostics (digital cameras and light sources) to meet a wide range of combustion research requirements. Experiments are conducted in the chamber by remote control from the ISS Payload Operations Center (ISSPOC) or the Principal Investigator’s (PI’s) home institution.
The CIR hardware is mounted in an International Standard Payload Rack (ISPR), with a Passive Rack Isolation System (PaRIS), that provides the supporting elements for the CIR subsystems and mechanical connections to the US Laboratory Module. The PaRIS enhances the microgravity environment for the CIR experiment by attenuating on-orbit vibration transmitted from the Destiny Module to the CIR. The Combustion Integrated Rack (CIR) features a 100-liter combustion chamber surrounded by optical and other diagnostic packages including a gas chromatograph
The centerpiece of the CIR structural sub-system is the optics bench. The optics bench supports the combustion chamber and the key interface for the diagnostics packages, gas resource distribution, cooling to the packages, and key control avionics. The optics bench can translate out of the ISPR volume and rotate to allow access to the back of the bench. The combustion chamber provides the containment for the combustion experiments along with eight removable, optical windows for the diagnostics. A set of experiments, such as liquid fuels, utilize an insert into the combustion chamber for performing specific science necessary operations (fuel deployment, ignition, etc.). The environmental subsystem utilizes air and water to remove heat generated by the CIR and payload hardware. The Electrical Power Control Unit (EPCU) is the heart of the electrical subsystem. All power from ISS flows through the EPCU. The EPCU provides power management and control functions, as well as fault protection. Payload hardware has access to 120 VDC (up to 1400 W) and 28 VDC (up to 672 W) of power from the EPCU. The CIR provides payloads with access to the ISS gaseous nitrogen and vacuum systems through the gas interface subsystem. These resources are available to support experiment operations such as the evacuating the combustion chamber and providing nitrogen for establishing the experiments atmospheric conditions. The CIR Command and Data Management Subsystem (CDMS) provides command and data handling for both facility and payload hardware. The main components of the CIR CDMS are the Input Output Processor(main command and control computer), the Image Processing and Storage Unit (interface with digital cameras), and the Fluids Science Avionics Package (additional control and data acquisition capability for the payloads). In addition, the CMDS can support real-time image analysis as well as post-processing data capabilities.
The CIR design allows different experiment packages within the combustion chamber to be removed, replaced or upgraded. Modular diagnostics are mounted on the optics bench and are easily repositioned. Standard diagnostic packages, constructed from modular elements provide key diagnostic capabilities for the CIR. These are a High Bit Depth/Multispectral Imaging Package (HiBMs), Low Light Level Camera Packages, and an Illumination Package.
The CIR and associated ground systems will offer the Principal Investigators the opportunity to participate in the conduct of their experiment on-board the ISS through remote operation and observation. Once a test point has been completed, the PI can assess the results and provide information for changes to the test matrix.
The first insert, or “mini-facility”, that was developed and integrated in the CIR is the Multi-User Droplet Combustion Apparatus (MDCA). The MDCA is designed to accommodate different droplet combustion science experiments. It consists of two major components: a chamber insert assembly and an avionics package. The chamber insert assembly is a framework for mounting the internal components that consist of the droplet dispensing and deployment mechanisms, igniters, fiber, deployment camera, and radiometers. It is mounted on guide rails in the CIR combustion chamber. The MDCA avionics package, located on the backside of the CIR optics bench, provides for the command, control, and data handling of the MDCA insert.
The first experiment in CIR to utilize the MDCA insert was the Flame Extinguishment in Microgravity experiment (FLEX). The FLEX investigation will utilize the spherically symmetric geometry of burning fuel droplets as a model environment for determining the effectiveness of gaseous fire suppressants in microgravity. This initial research provided valuable data in the area of spacecraft fire safety to help define large-scale fire suppression tests and selection of the fire suppressant for next generation crew exploration vehicles.
The Italian Combustion Experiment for Green Air (ICE-GA) studied single droplets of various biofuel mixtures to determine how efficiently they burn. By studying fuel burning in space, researchers can study evaporation and combustion without the influence of gravity. Data obtained in the ICE-GA experiments is currently being analyzed to help develop a database of evaporation and combustion statistics for a variety of biofuel mixtures. This data can be used in computer models, which can evaluate biofuel efficiency and accelerate the adoption of the most efficient fuel mixtures.
Future investigations with the CIR include the following:
MDCA/FLEX-2J – 2015
The FLEX-2J experiment will be operated within the current CIR insert, Multi-user Droplet Combustion Apparatus (MDCA), to investigate the influence of a flame spreading along a linear array of droplets. The experiment will examine the flame spread and droplet motion interactions. The information will help in the understanding of the mechanisms of a flame spread in a fuel spray.
MDCA/Cool Flames Experiment – 2016
The Cool Flames Experiment (CFE) will be operated within the current CIR insert, MDCA, to investigate the structure and dynamics of the cool flame mode of burning during the second stage of a non-premixed droplet flame. Understanding this burning regime can lead to decreased emissions and increased efficiency in advanced low temperature internal combustion engines, as well as a better understanding for fire safety in space.
ACME – 2017-2019
The Advanced Combustion via Microgravity Experiments (ACME) is a series of experiments that will be performed in the CIR with the incorporation of a new insert, along with a new color diagnostic package and associated control box. The experiments will focus on gaseous fuels investigations to study combustion structure and stability near flammability limits, soot inception, surface growth, and oxidation processes. Also, an investigation on nitrogen exchange to reduce emissions will be performed. The data developed will help verify computation models to enable the design of high efficiency, low emission combustors and improve our understanding of nearly every practical combustion device.
SoFIE – 2019-2012
The Solid Fuel Ignition and Extinction (SoFIE) experiments is a series experiments that will be performed in the CIR with the incorporation of a new insert. The experiments will study and characterize ignition and flammability of solid spacecraft materials in practical geometries and realistic atmosphere conditions. The data will help improve EVA suit designs, determine selection of proper materials, improve understanding of early fire growth behavior, validate existing models, and determine optimal suppression techniques.
Read the Adobe Acrobat (PDF) Principal Investigator’s Guide to the CIR Payload Accommodations document for more information or the public relations brochure Combustion Research in the Fluids and Combustion Facility.
Contacts at NASA Glenn Research Center
Project Manager: Robert Corban, NASA GRC