Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “thermal system modeling”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14

Fuel Cell Model Validation with Power Module Test Data

The AES Modular Power Systems (AMPS) Fuel Cell team at the NASA Glenn Research Center (GRC) has created a Microsoft Excel model of a regenerative fuel cell (RFC) system for potential lunar and Martian applications. Due to some limitations of this model, including the ability to predict transient effects in the thermal and fluidic performance of the system, a system-level transient thermal/fluids model was desired. GT-SUITE is a transient multi-physics simulation tool that is popular in the automotive industry and has a built-in template for proton exchange membrane (PEM) fuel cells. However, terrestrial fuel cells used in the automotive industry vary significantly from aerospace fuel cells. A validation effort was undertaken to compare GT SUITE model results to actual data collected during the 2015 AMPS (Advanced Exploration Systems (AES) Modular Power Systems) Power Module Demonstration in which the AMPS team used a PEM fuel cell system to power a 478 kilogram rover assembly at the Dunes test site located at GRC. The purpose of the model was to evaluate the efficacy of using GT SUITE to model a non-flow through PEM fuel cell system. The validation effort examined electrochemical performance including fuel cell stack voltage and power supplied, the thermal performance of the stack namely stack temperature and heat rejection rates, and the fluidic performance of the system including pressures, reactant consumption, and water production rates.

Model Validation↗

Thermal Analysis of the MC-1 Chamber/Nozzle

This paper will describe the thermal analysis techniques used to predict temperatures in the film-cooled ablative rocket nozzle used on the MC-1 60K rocket engine. A model was developed that predicts char and pyrolysis depths, liner thermal gradients, and temperatures of the bondline between the overwrap and liner. Correlation of the model was accomplished by thermal analog tests performed at Southern Research, and specially instrumented hot fire tests at the Marshall Space Flight Center. Infrared thermography was instrumental in defining nozzle hot wall surface temperatures. In-depth and outboard thermocouple data was used to correlate the kinetic decomposition routine used to predict char and pyrolysis depths. These depths were anchored with measured char and pyrolysis depths from cross-sectioned hot-fire nozzles. For the X-34 flight analysis, the model includes the ablative Thermal Protection System (TPS) material that protects the overwrap from the recirculating plume. Results from model correlation, hot-fire testing, and flight predictions will be discussed.

Davis, Darrell W.↗

Thermal Analysis of the Fastrac Chamber/Nozzle

This paper will describe the thermal analysis techniques used to predict temperatures in the film-cooled ablative rocket nozzle used on the Fastrac 60K rocket engine. A model was developed that predicts char and pyrolysis depths, liner thermal gradients, and temperatures of the bondline between the overwrap and liner. Correlation of the model was accomplished by thermal analog tests performed at Southern Research, and specially instrumented hot fire tests at the Marshall Space Flight Center. Infrared thermography was instrumental in defining nozzle hot wall surface temperatures. In-depth and outboard thermocouple data was used to correlate the kinetic decomposition routine used to predict char and pyrolysis depths. These depths were anchored with measured char and pyrolysis depths from cross-sectioned hot-fire nozzles. For the X-34 flight analysis, the model includes the ablative Thermal Protection System (TPS) material that protects the overwrap from the recirculating plume. Results from model correlation, hot-fire testing, and flight predictions will be discussed.

Davis, Darrell↗

Performance Evaluation of Intravehicular Activity Spacesuit Without the Use of a Liquid Cooling Garment

The Orion Crew Survival Systems (OCSS) suit is equipped with safety technology that protects the crew during launch and re-entry and Intravehicular Activities (IVA). It was designed to be used with a Liquid Cooling Garment (LCG), an undergarment with tubes that circulate water to remove excess heat from a crew member. The objective of this study is to determine if the Modified Advanced Crew Escape Suit (MACES), which has very similar material, assembly, and pressure characteristics as the OCSS suit, can be used without the LCG to maintain the crew within their heat storage requirements where exceedances can lead to cognitive and physiological impairment. Testing was completed for both hot and cold environments where test subjects wore varying configurations of the MACES suit ensemble without the LCG. The tests were conducted in a temperature and humidity-controlled chamber with four test subjects ranging from extra small to large. Target metabolic rates were reached using an arm ergometer. To represent the different suit configurations seen in the concept of operations, the suit was tested with visor-down, visor-up, and without helmet and gloves. The test data was analyzed to determine how the environment, test subject size, metabolic rate, and suit configuration affected heat storage. Furthermore, the test data was used to correlate the METMAN model, a transient metabolic man program that simulates the heat transfer within a crew member’s body and from a crew member to the surrounding environment. The METMAN correlation showed good agreement between predicted heat storage and test data at the end of the test duration, with a coefficient of determination (R 2 ) value of 0.8999 for visor-down cases and R 2 of 0.8902 for visor-up and helmet off cases. A correlated METMAN model allows for the analysis and prediction of IVA suit performance without an LCG in additional scenarios.

Spacesuit↗

Thermal control for the ground simulation of a space IR sensor system

Active and passive thermal controls for simulations of a space IR sensor system operating in cryogenic temperatures were designed, built, and tested from a component level to a system level. The test results from component tests and integrated system tests have compared very well with theoretical predictions, and thus verify component and integrated thermal math models. These verified models can be modified for use to predict flight systems thermal performance. Thermal vacuum simulations and demonstrations of a space IR system consisted of a target and background scene generator, telescope mirrors supported by a graphite-epoxy metering structure, and an IR sensor. These components are required to operate at cryogenic temperature levels. Each component has its unique thermal control needs. Descriptions are presented of thermal control systems for the test article from component design level to integrated system level along with discussions of component and integrated demonstration tests, and correlation of test data with thermal finite difference models.

Lee, E.↗

Numerical Investigation of Heat Transfer and Fluid Flow within Electrochemical Hydrogen Peroxide Generation Unit

Long-term manned space missions require the onboard production of disinfectants essential for maintaining crew health and supporting life systems. Currently, disinfection aboard the International Space Station (ISS) relies on disposable wetted wipes, which are regularly resupplied from Earth. This approach imposes a significant burden on resupply logistics, storage, and waste management. To address these challenges and support future missions, efforts are underway to develop an in-situ solution that electrochemically generates hydrogen peroxide disinfectant using onboard resources. In collaboration with NASA, Faraday Technology, Inc. has advanced this concept through a series of Small Business Innovation Research (SBIR) projects, resulting in the development of a Peroxide Generation Unit (PGU). The PGU can produce up to 3 wt.% hydrogen peroxide on-demand at a rate of 1 liter per day, providing a sustainable alternative to Earth-dependent supplies. The resulting aqueous hydrogen peroxide (H₂O₂) is an effective disinfectant, safe for crew use, compatible with spacecraft systems, and free from volatiles, off-gassing, or residues. This innovation offers a reliable, efficient solution for onboard disinfection, reducing dependence on Earth-based resupply while ensuring the health and safety of space crews. Generating hydrogen peroxide at the required rate needs high voltages and currents, exceeding 20V and 2A respectively, which leads to significant heat generation from Joule heating. This temperature rise poses a risk to sensitive system components, especially critical and expensive membranes that can degrade under thermal stress. To mitigate this risk, the thermal, fluid, and electrical flows within the system are modeled computationally using the commercial software COMSOL. The numerical simulations are validated against experimental data from both sub-scale and alpha-scale systems. Once verified, the model is employed to identify thermal hotspots, investigate their underlying causes, and explore solutions to prevent them.

Life Support Systems (LSS)↗

A title-gap flow model for use in aerodynamic loads assessment of space shuttle thermal protection system: Parallel gap faces

The problem of predicting aerodynamic loads on the insulating tiles of the space shuttle thermal protection system (TPS) is discussed and seen to require a method for predicting pressure and mass flux in the gaps between tiles. A mathematical model of the tile-gap flow is developed, based upon a slow viscous (Stokes) flow analysis, and is verified against experimental data. The tile-gap pressure field is derived from a solution of the two-dimensional Laplace equation; the mass-flux vector is then calculated from the pressure gradient. The means for incorporating this model into a lumped-parameter network analogy for porous-media flow is given. The means for incorporating this model into a lumped-parameter network analogy for porous-media flow is given. The flow model shows tile-gap mass flux to be very sensitive to the gap width indicating a need for coupling the TPS flow and tile displacement calculation. Analytical and experimental work to improve TPS flow predictions and a possible shuttle TPS hardware modification are recommended.

Dwoyer, D. L.↗

Fluid Distribution for In-space Cryogenic Propulsion

The ultimate goal of this task is to enable the use of a single supply of cryogenic propellants for three distinct spacecraft propulsion missions: main propulsion, orbital maneuvering, and attitude control. A fluid distribution system is sought which allows large propellant flows during the first two missions while still allowing control of small propellant flows during attitude control. Existing research has identified the probable benefits of a combined thermal management/power/fluid distribution system based on the Solar Integrated Thermal Management and Power (SITMAP) cycle. Both a numerical model and an experimental model are constructed in order to predict the performance of such an integrated thermal management/propulsion system. This research task provides a numerical model and an experimental apparatus which will simulate an integrated thermal/power/fluid management system based on the SITMAP cycle, and assess its feasibility for various space missions. Various modifications are done to the cycle, such as the addition of a regeneration process that allows heat to be transferred into the working fluid prior to the solar collector, thereby reducing the collector size and weight. Fabri choking analysis was also accounted for. Finally the cycle is to be optimized for various space missions based on a mass based figure of merit, namely the System Mass Ratio (SMR). -. 1 he theoretical and experimental results from these models are be used to develop a design code (JETSIT code) which is able to provide design parameters for such a system, over a range of cooling loads, power generation, and attitude control thrust levels. The performance gains and mass savings will be compared to those of existing spacecraft systems.

Lear, William↗

Development of an improved model for runback water on aircraft surfaces

A computer simulation for 'running wet' and evaporative aircraft anti-icing systems is developed. The model is based on the analysis of the liquid water film which forms in the regions of direct impingement and, then, breaks up near the impingement limits into rivulets. The wetness factor distribution resulting from the film breakup and the rivulet configuration on the surface are predicted using a stability analysis theory and the laws of mass energy conservation. The solid structure is modeled as a multiple layer wall. The anti-icing system modeled is of the thermal type utilizing hot air and/or electrical heating elements embedded within the wall layers. Experimental observations revealing some of the basic physics of the water flow on the surface are presented. Detailed qualitative documentation of the tests are given. Several numerical examples are considered, and the effect of some of the involved parameters on the system performance are investigated.

Al-Khalil, Kamel M.↗

Rates of fluvio-thermal erosion on Mars

In order to get some ideas about the order of magnitude of fluvio-thermal recession rate, a mathematical thermal model for Martian outflow channels is proposed. This model corresponds to a system undergoing a permanent thermal regime where the surface temperature is constant and equal to the phase change temperature (due to the immediate removal of melted materials). This is an ablation model. For its application, estimations of the heat transfer coefficient h and thermal flux q are necessary. Determination of these coefficients needs the calculation of dimensionless numbers (Reynolds, Prandtl, and Nusselt), and the consideration of turbulent regime of the flow.

Aguirre-Puente, J.↗

Numerical Thermal Model of a 30-cm NSTAR Ion Thruster

A thermal computer model of the NSTAR (Nasa Solar Electric Propulsion Technology Applications Readiness) xenon ion thruster has been produced using a lumped parameter thermal nodal network scheme. This model contains 104 nodes on the thruster and was implemented using SINDA (Systems Improved Numerical Differencing Analyzer) and TRASYS (Thermal Radiation Analyzer System) on various UNIX workstations. The model includes radiation and conduction heat transfer, the effect of plasma interaction on the thruster, and an account for finely perforated surfaces. The model was developed in conjunction with an NSTAR thruster outfitted with approximately 20 thermocouples for thermal testing at the NASA Lewis Research Center. The results of these experiments were used to calibrate and confirm the computer model first without and then with the plasma interaction. The calibrated model was able to predict discharge chamber temperatures to within 10 C of measured temperatures. To demonstrate the ability of the model under various circumstances the heat flux was examined for a thruster operating in the environment of space.

VanNoord, Jon↗

Development of a Thermal Management System for Electrified Aircraft

This paper describes the development and optimization of a conceptual thermal management system for electrified aircraft. Here, a vertical takeoff and landing (VTOL) vehicle is analyzed with the following electrically sourced heat loads considered: motors, generators, rectifiers, and inverters. The vehicle will employ liquid-cooling techniques in order to acquire, transport, and reject waste heat from the vehicle. The purpose of this paper is to threefold: 1) Present a potential modeling framework for system level thermal management system simulation, 2) Analyze typical system characteristics, and 3) Perform optimization on a system developed for a specific vehicle to minimize weight gain, power utilization, and drag. Additionally, the paper will study the design process, specifically investigating the differences between steady state and transient sizing, comparing simulation techniques with a lower fidelity option and quantifying expected error.

Chapman, Jeffryes W.↗

Thermal and optical performance of encapsulation systems for flat-plate photovoltaic modules

The electrical power output from a photovoltaic module is strongly influenced by the thermal and optical characteristics of the module encapsulation system. Described are the methodology and computer model for performing fast and accurate thermal and optical evaluations of different encapsulation systems. The computer model is used to evaluate cell temperature, solar energy transmittance through the encapsulation system, and electric power output for operation in a terrestrial environment. Extensive results are presented for both superstrate-module and substrate-module design schemes which include different types of silicon cell materials, pottants, and antireflection coatings.

Minning, C. P.↗

New Developments In NASA’s Entry Systems Modeling Project

This paper describes recent developments for modeling entry, descent, and landing (EDL)of spacecraft in support of NASA’s exploration missions. Mission-specific research and model development for entry systems occurs across the Agency (e.g., within flight programs like Artemis/Orion and Mars Sample Return), however the aim of this paper is to discuss the research conducted by NASA’s Entry Systems Modeling (ESM) Project, which serves as the Agency’s only effort dedicated to advancing modeling capabilities that cross-cut multiple technical disciplines, missions and destinations. The ESM portfolio is developed to address the specific needs expressed by a cross-section of NASA stakeholders, including flight and research projects, technical leadership, and subject matter experts. Technology development in ESM is organized and prioritized from a system-level perspective, resulting in four broad technical areas of investment: (1) Thermal Protection System (TPS) material modeling, (2) Shock layer kinetics and radiation, (3) Aerosciences, and (4) Guidance, navigation, and control. In addition to the core technical areas, special topics are rolled into the project portfolio as specific demands arise. Current special topics include TPS Certification by Analysis, improving understanding of woven TPS material performance; Hypersonic Wake Flows, assessing and improving predictions of base flows; and the MEDLI2 Deep Dive, furthering analysis of data obtained during Mars2020 mission’s entry and descent at Mars. Key results from each of these areas are presented in this paper, along with associated references to serve as a roadmap for other EDL researchers to access NASA’s publications.

Aaron M Brandis↗

From Exploration Flight Test-1 to Artemis II--A NASA Langley's Orion Aerosciences Overview

The Orion Aerosciences program at NASA Langley has played a central role in advancing the aerodynamic and aeroheating prediction capabilities required for the Orion crew vehicle’s return from deep space. This presentation provides a technical overview of aerosciences contributions spanning Exploration Flight Test-1 (EFT-1), Artemis I, and the ongoing post-flight analysis of Artemis II. EFT-1 provided the first high-energy entry dataset for Orion, enabling critical validation of aerodynamic force and moment predictions, static and dynamic stability characteristics, and aeroheating environments at relevant flight Mach and Reynolds numbers. Flight-derived pressure data were used to refine the Flush Air Data System (FADS) methodology for atmospheric density reconstruction and to improve Best Estimated Trajectory (BET) solutions. The EFT-1 data also offered key insights into heat shield performance, including char layer recession, in-depth thermal response, and material retention behavior under flight conditions, informing updates to both thermal response models and uncertainty quantification practices. Building on EFT-1, Artemis I extended the database to true lunar-return conditions. Observations of heat shield performance, including localized char loss, bondline response, and recession variability, provided an unprecedented opportunity to reassess Thermal Protection System (TPS) and aeroheating modeling assumptions. Aerodynamic reconstruction efforts incorporated improved FADS calibration, enhanced atmospheric modeling, and refined force and moment databases to reduce trajectory and load uncertainties. Aeroheating comparisons between pre-flight predictions and flight data enabled targeted model updates, particularly in transitional flow environments and wake heating regions. For Artemis II, these lessons were systematically incorporated into the pre-flight prediction process. Updates included refined aerodynamic databases anchored to flight-validated corrections, improved density estimation and BET methodologies using enhanced database interpolation algorithm and FADS modeling, and revised aeroheating design environments informed by Artemis I material response observations. By the time of the workshop, Artemis II post-flight analysis will be underway, and preliminary findings will be presented where available, including early comparisons of aerodynamic reconstruction, atmospheric density estimation, and thermal protection system performance relative to updated predictions. Collectively, this body of work is a testament to the dedicated and multidisciplinary team whose sustained efforts have contributed to the program’s success and to the progressive maturation of Orion aerosciences modeling through numerical modeling, ground and flight data assimilation. The integrated advancement of aerodynamics, trajectory reconstruction, FADS-based density estimation, and aeroheating analysis has reduced predictive uncertainty and strengthened confidence for future crewed lunar and deep-space missions.

Orion↗

Thermal barrier coating life prediction model development

This report describes work performed to determine the predominat modes of degradation of a plasma sprayed thermal barrier coating system and to develop and verify life prediction models accounting for these degradation modes. The primary TBC system consisted of a low pressure plasma sprayed NiCrAlY bond coat, an air plasma sprayed ZrO2-Y2O3 top coat, and a Rene' 80 substrate. The work was divided into 3 technical tasks. The primary failure mode to be addressed was loss of the zirconia layer through spalling. Experiments showed that oxidation of the bond coat is a significant contributor to coating failure. It was evident from the test results that the species of oxide scale initially formed on the bond coat plays a role in coating degradation and failure. It was also shown that elevated temperature creep of the bond coat plays a role in coating failure. An empirical model was developed for predicting the test life of specimens with selected coating, specimen, and test condition variations. In the second task, a coating life prediction model was developed based on the data from Task 1 experiments, results from thermomechanical experiments performed as part of Task 2, and finite element analyses of the TBC system during thermal cycles. The third and final task attempted to verify the validity of the model developed in Task 2. This was done by using the model to predict the test lives of several coating variations and specimen geometries, then comparing these predicted lives to experimentally determined test lives. It was found that the model correctly predicts trends, but that additional refinement is needed to accurately predict coating life.

Hillery, R. V.↗

Testbed for an autonomous system

In previous works we have defined a general architectural model for autonomous systems, which can easily be mapped to describe the functions of any automated system (SDAG-86-01), and we illustrated that model by applying it to the thermal management system of a space station (SDAG-87-01). In this note, we will further develop that application and design the detail of the implementation of such a model. First we present the environment of our application by describing the thermal management problem and an abstraction, which was called TESTBED, that includes a specific function for each module in the architecture, and the nature of the interfaces between each pair of blocks.

Dikshit, Piyush↗

TRASYS/SSPSTA thermal modeling comparison

The Thermal Radiation Analysis System (TRASYS) and the Simplified Shuttle Payload Analyzer (SSPTA) are applied for the purpose of comparison to the Solar Maximum Repair Mission (SMRM) and Astro-1/UVT (Ultraviolet Telescope), making use also of the System Improved Numerical Differencing Analyzer (SINDA). The majority of radiation conductances obtained from the TRASYS and SSPTA computer codes are shown to be within + or - 20 percent of each other, though the interchange factors associated with some crucial components of the system are located beyond this region. A sample model is also considered, which consists of an outer and an inner boxes with emisivities of 0.32 and 0.80 respectively. It is concluded that a thorough, methodical comparison between the two codes is necessary.

Noravian, H.↗