Flow Boiling & Condensation Experiment (FBCE)
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flow boiling, two-phase heat transfer coefficient,↗
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Spin Investigation Of A 1/20-Scale Model Of An Unswept-Wing, Twin-Engine, Observation Airplane
An investigation was conducted in the Langley 20-foot free-spinning tunnel on a 1/20-scale model of an unswept-wing, twin-engine, observation airplane. The effects of control settings and movements on the erect spin and recovery characteristics for the normal loading and the most rearward center-of-gravity loading (external wing tanks full) were determined. Also, tests were made to determine the effect on the spin and recovery characteristics of a large radar store, of empty and full external wing tanks, and of an asymmetrical condition when one empty or one full external wing tank is carried. Spin-recovery parachute tests were also performed. The results of the tests indicate that erect spins obtained on the airplane for the normal loading should be satisfactorily terminated by rudder reversal to full against the spin, ailerons moved to with the spin, followed one-half turn later by forward movement of the stick to neutral. With the radar store, with wing tanks empty, or with an asymmetrical condition when one empty tank is on either wing, satisfactory recoveries can be obtained by using the same technique as for the normal loading. Recoveries for the model with a rearward center-of-gravity loading (external wing tanks full) or with a full tank on the wing inboard of the spin axis will be slow to unsatisfactory with rudder reversal to full against the spin followed by brisk forward stick movement. With a full tank on the wing outboard of the spin axis, the recoveries will be satisfactory. Spins in the landing configuration should be terminated by first retracting the flaps, slats, and landing gear, after which recovery should be attempted immediately by using the recovery technique recommended for the normal loading condition. Inverted spins can be satisfactorily terminated by rudder reversal to full against the spin followed by neutralization of the longitudinal and lateral controls. A 12.7-foot-diameter tail parachute with a towline length of 21.7 feet and a drag coefficient of 0.65 should be satisfactory for recoveries from erect and inverted demonstration spins when used simultaneously with movement of rudder to neutral.
SPIN↗
Flow Visualization, Heat Transfer, and Critical Heat Flux of Flow Boiling in Earth Gravity with Saturated Liquid-Vapor Mixture Inlet Conditions – In Preparation for Experiments Onboard the International Space Station
This study investigates flow boiling of n-Perfluorohexane with saturated two-phase mixture inlet in a rectangular channel of dimensions 114.6-mm heated length, 2.5-mm width, and 5 mm-height. The experiments were performed as part of the Mission Sequence Testing of the Flow Boiling and Condensation Experiment’s (FBCE) Flow Boiling Module (FBM) in the vertical upflow configuration in Earth gravity using the same experimental system that was launched to the International Space Station (ISS) in August 2021. The operating parameters varied are heating configuration (single- and double-sided), mass velocity (380 – 2400 kg/m2s), inlet quality (0.011 – 0.519), and inlet pressure (120 – 179 kPa). High-speed video photographs are presented to explain the two-phase flow patterns within the channel’s heated length. Flow patterns are constituted by low-density and high-density fronts moving along the channel, with the high-density fronts gradually reducing in length due to evaporation. Heat transfer results in terms of flow boiling curves, streamwise wall temperature profiles, streamwise heat transfer coefficient profiles, and average heat transfer coefficients are presented and trends discussed. CHF data from the present experiments are combined with prior databases to compile a consolidated FBCE-CHF database for saturated inlet to expand the ranges of operating conditions and include other flow orientations in Earth gravity. Experimental CHF trends are also discussed. The interfacial lift-off model shows a good CHF predictive accuracy evidenced by a mean absolute error of 11.97% for this consolidated database after constraining it to mass velocities greater than or equal to 500 kg/m2s. Finally, this study confirmed reliability of the upcoming ISS experiments for saturated inlet conditions and the collected Earth-gravity data will be compared to ISS microgravity data.
Flow boiling↗
Two-dimensional Cascade Investigation of the Maximum Exit Tangential Velocity Component and Other Flow Conditions at the Exit of Several Turbine Blade Designs at Supercritical Pressure Ratios
The nature of the flow at the exit of a row of turbine blades for the range of conditions represented by four different blade configurations was evaluated by the conservation-of-momentum principle using static-pressure surveys and by analysis of Schlieren photographs of the flow. It was found that for blades of the type investigated, the maximum exit tangential-velocity component is a function of the blade geometry only and can be accurately predicted by the method of characteristics. A maximum value of exit velocity coefficient is obtained at a pressure ratio immediately below that required for maximum blade loading followed by a sharp drop after maximum blade loading occurs.
TURBINES - AXIAL FLOW↗
Carbon-Temperature-Water Change Analysis for Peanut Production Under Climate Change: A Prototype for the AgMIP Coordinated Climate-Crop Modeling Project (C3MP)
Climate change is projected to push the limits of cropping systems and has the potential to disrupt the agricultural sector from local to global scales. This article introduces the Coordinated Climate-Crop Modeling Project (C3MP), an initiative of the Agricultural Model Intercomparison and Improvement Project (AgMIP) to engage a global network of crop modelers to explore the impacts of climate change via an investigation of crop responses to changes in carbon dioxide concentration ([CO2]), temperature, and water. As a demonstration of the C3MP protocols and enabled analyses, we apply the Decision Support System for Agrotechnology Transfer (DSSAT) CROPGRO-Peanut crop model for Henry County, Alabama, to evaluate responses to the range of plausible [CO2], temperature changes, and precipitation changes projected by climate models out to the end of the 21st century. These sensitivity tests are used to derive crop model emulators that estimate changes in mean yield and the coefficient of variation for seasonal yields across a broad range of climate conditions, reproducing mean yields from sensitivity test simulations with deviations of ca. 2% for rain-fed conditions. We apply these statistical emulators to investigate how peanuts respond to projections from various global climate models, time periods, and emissions scenarios, finding a robust projection of modest (<10%) median yield losses in the middle of the 21st century accelerating to more severe (>20%) losses and larger uncertainty at the end of the century under the more severe representative concentration pathway (RCP8.5). This projection is not substantially altered by the selection of the AgMERRA global gridded climate dataset rather than the local historical observations, differences between the Third and Fifth Coupled Model Intercomparison Project (CMIP3 and CMIP5), or the use of the delta method of climate impacts analysis rather than the C3MP impacts response surface and emulator approach.
climate change↗
Effects of Heating Configuration and Operating Parameters on Heat Transfer and Interfacial Physics of Microgravity Flow Boiling With Subcooled Inlet Conditions –Experiments Onboard the International Space Station
This study is part of the Flow Boiling and Condensation Experiment (FBCE), a collaborative effort between the Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) and the NASA Glenn Research Center. The FBCE fitted with the Flow Boiling Module (FBM) was launched to the International Space Station (ISS) in August 2021 and experiments were successfully performed from February to July 2022 to amass a large microgravity-flow-boiling database. This study is focused on heat transfer and flow visualization of microgravity flow boiling of n-Perfluorohexane in a rectangular channel of 5.0 mm height, 2.5 mm width (heated), and 114.6 mm length, with subcooled inlet conditions. High-speed-video photography is utilized to present flow patterns and temporal interfacial behavior. Heat transfer results are presented in the form of flow boiling curves and both parametric curves and streamwise profiles of wall temperature and heat transfer coefficient. Firstly, the parametric effects of mass velocity (199.4 – 3200.0 kg/m 2 s), inlet subcooling (0.2 – 46.0°C), and inlet pressure (124.2 – 176.7 kPa), on the aforementioned aspects are assessed for double-sided heating to establish them for a microgravity environment. Of these three parameters, mass velocity and inlet subcooling mostly determine the microgravity flow boiling behavior, while inlet pressure plays an insignificant role. Flow patterns for double-sided heating are more complex than those for single-sided heating due to interaction between the two vapor layers. Vapor interaction is minimized at high subcoolings and high mass velocities due to strong condensation offered by the subcooled bulk liquid layer separating them. Despite the different flow patterns, both single- and double-sided heating generally result in similar parametric trends and local heat transfer coefficients for similar operating conditions. Flow instabilities manifest as temporal flow anomalies and temperature oscillations, and their severity increases with increasing boiling number. Secondly, the effects of heating configuration are analyzed by comparing and contrasting several aspects of single- and double-sided heating data. The heat fluxes at which onset of nucleate boiling degradation (ONBD) and critical heat flux (CHF) occur are distinctly different for single- and double-sided heating. There exists a threshold inlet subcooling demarcating the dominance of flow acceleration and condensation effects in vapor removal from the near-wall region and replenishment of fresh liquid for boiling. Above the threshold, condensation from the near-wall region is dominant and single-sided heating yields higher heat fluxes, and below it, acceleration is dominant and double-sided yields higher heat fluxes. At mass velocity in the range of 200 – 2400 kg/m 2 s, the threshold inlet subcooling lies in the approximate range of 20 – 30°C (corresponding inlet quality of roughly -0.40 – -0.20).
Microgravity↗
Results of thermal vacuum tests for the PASP Plus flight panels
The PASP+ experiment is collection of 16 individual cell strings on 12 different photovoltaic modules, representing a wide variety of cell and array technologies, which will be launched from a Pegasus in early 1993. The main objectives of the experiment are to obtain environmental interaction data between the modules and the space plasma; and to obtain radiation damage data on the newer types of cells. The orbit will be about 1050 nautical miles by 190 nautical miles with an inclination of 70 degrees. During late June and early July of this year, we took the PASP+ panels with all 12 modules and the flight controller to Boeing for a series of thermal vacuum tests. The main objectives of these tests were to verify the thermal balance model of the space experiment; to obtain good data for temperature coefficients of the various modules; and to have an 'end-to-end' test of the modules and controller. We will present data on the module temperatures and the measured temperature coefficients. We shall discuss the limitations of the test setup and some of the assumptions that were made. We shall also present some module performance as a function of temperature.
Guidice, Don↗
Experimental, Computational, Theoretical and Analytical Investigation of Flow Boiling in Reduced Gravity
Two-phase thermal management systems are far superior to their single-phase counterparts because of their ability to capitalize on the coolant’s both sensible and latent heats, thereby yielding orders of magnitude higher heat transfer coefficients and smaller system footprints. A vital knowledge necessary for their implementation in future space systems is performance in microgravity. Long-duration microgravity experiments are necessary to obtain reliable databases, which would then be used to build reliable predictive tools. To achieve this goal, investigators at the Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) and the NASA Glenn Research Center (NASA-GRC) have been collaborating towards the development of the Flow Boiling and Condensation Experiment (FBCE) and eventual execution onboard the International Space Station (ISS). FBCE has now matured to a point where it is ready for transport to the ISS, where first tests will be conducted using the Flow Boiling Module (FBM). In preparation for the ISS tests, a series of pre-launch Mission Sequence Tests (MSTs) was performed at GRC in Earth gravity with FBM mounted in a vertical upflow orientation using n-perfluorohexane as working fluid. The pre-launch tests included variations of flow rate, surface heat flux, inlet conditions, and both single-sided and double-sided wall heating. This presentation will summarize experimental results from these tests as well as both analytic and theoretical tools for prediction of two-phase heat transfer coefficient and critical heat flux (CHF). Also discussed will be an assessment of predictive accuracy of these tools against the experimental data.
Mission Sequence tests↗
Results of thermal vacuum tests for the PASP+ flight modules
The PASP PLUS (Photovoltaic Array Space Power Plus Diagnostics) program is a photovoltaic experiment which will be flown on the Air Force satellite APEX (Advanced Photovoltaic And Electronic Experiment). APEX will be launched with a Pegasus during the summer of 1993. There are two other small experiments on APEX but PASP+ is the largest, uses the most power, and accounts for over 90 percent of the data requirements. The orbit is elliptical with apogee and perigee of 1050 and 190 nautical miles respectively. The inclination is 70 deg. The two main objectives of PASP+ are to determine the interactions between high voltage arrays and the space plasma environment and to determine the radiation damage characteristics of several newer types of solar cells. In order to determine the interactions with the space plasma, several of the individual cell strings will be biased to voltages up to plus or minus 500 V, and leakage currents and arcing rates will be measured. The radiation degradation characteristics will be determined by the continuous monitoring of I-V data for all of the cell strings. As part of an overall testing program, the PASP+ panels and controller were put through a thermal vacuum test in order to check the thermal analysis, obtain temperature coefficients for the individual modules, and have an end-to-end test of the entire PASP+ experiment. This thermal vacuum test is described briefly and the results obtained during that testing are discussed.
Curtis, Henry↗
Preliminary Results of an Investigation at Transonic Speeds to Determine the Effects of a Heated Propulsive Jet on the Drag Characteristics of a Related Series of Afterbodies
Preliminary results are presented from an investigation to determine the influence of afterbody geometry on the effects of a sonic propulsive jet at transonic speeds. The results presented are base pressure coefficient and afterbody pressure-drag coefficient as a function of jet pressure ratio for different values of Mach number and jet temperature. Geometric parameters investigated include boattail angle, jet-to-model diameter ratio, and jet-to-base diameter ratio.
Henry, Beverly Z , Jr↗
Supplementary Investigation in the Langley Free-Spinning Tunnel of a 1/20-Scale Model of the Douglas XF4D-1 Airplane Including Spin-Recovery Parachute Tests of the Model Loaded to Simulate the Douglas F5D-1 Airplane
A supplementary investigation has been conducted in the Langley 20-foot free-spinning tunnel of a l/20-scale model of the Douglas XF4D-1 airplane to determine the effect of only neutralizing the rudder for recovery from an inverted spin, and the effect of partial aileron deflection with the spin for recovery from an erect spin. An estimation of the size parachute required for satisfactory recovery from a spin with the model ballasted to represent the Douglas F5D-1 (formerly the Douglas XF4D-2) airplane was also made. Results of the original investigation on the XF4D-1 design are presented in NACA RM SL50K30a. The results indicated that satisfactory recoveries from inverted spins of the airplane should be obtained by rudder neutralization when the longitudinal stick position is neutral or forward. Recoveries from erect spins from the normal-spin control configuration should be satisfactory by full rudder reversal with simultaneous movement of the ailerons to two-thirds with the spin. For the parachute tests with the model loaded to represent the F5D-1 airplane, the tests indicated that a 16.7-foot-diameter hemispherical-tail parachute (drag coefficient of 1.082 based on the projected area) with a towline 20.0 feet long (full- scale values) should be satisfactory for an emergency spin-recovery device during demonstration spins of the airplane.
Klinar, Walter J.↗
Cryo-Infrared Optical Characterization at NASA GSFC
The development of large space infrared optical systems, such as the Next Generation Space Telescope (NGST), has increased requirements for measurement accuracy in the optical properties of materials. Many materials used as optical components in infrared optical systems, have strong temperature dependence in their optical properties. Unfortunately, data on the temperature dependence of most of these materials is sparse. In this paper, we provide a description of the capabilities existing in the Optics Branch at the Goddard Space Flight Center that enable the characterization of the refractive index and absorption coefficient changes and other optical properties in infrared materials at cryogenic temperatures. Details of the experimental apparatus, which include continuous flow liquid helium optical cryostat, and a Fourier Transform Infrared (FTIR) spectrometer are discussed.
Boucarut, Ray↗
INITIAL ASSESSMENT OF SURFACE PRESSURE CHARACTERISTICS OF TWO ROTARY WING UAV DESIGNS
This paper presents results of an experimental investigation of two rotary-wing UAV designs. The primary goal of the investigation was to provide a set of interactional aerodynamic data for an emerging class of rotorcraft. The present paper provides an overview of the test and an introduction to the test articles, and instrumentation. Sample data in the form of fixed system pressure coefficient response to changes in configuration attitude and flight condition for both rotor off and on conditions are presented. The presence of the rotor is seen to greatly affect the magnitude of the response. Pressure coefficients were measured using both conventional pressure taps and via pressure sensitive paint. Comparisons between the two methods are presented and demonstrate that the pressure sensitive paint is a promising method; however, further work on the technique is required.
Jones, Henry E.↗
Investigation of the Spinning and Tumbling Characteristics of a 1/25-Scale Model of the Lockheed XFV-1 Airplane in the Langley 20-Foot Free-Spinning Tunnel
An investigation has been conducted in the Langley 20-foot free-spinning tunnel on a l/23-scale model of the Lockheed XFV-1 airplane to determine the effects of control setting and movement upon the erect-spin and recovery characteristics for a range of airplane loading conditions. A windmilling propeller was simulated on the model for some of the tests. The investigation included determination of the size of tail parachute required for emergency recovery from demonstration spins. The tumbling tendencies of the model were also investigated. The results indicated that any erect or inverted spin obtained on the airplane will be satisfactorily terminated if recovery is attempted by full rudder reversal accompanied by simultaneous lateral and longitudinal movement of the stick to neutral, The model test results showed that an 11.5-foot flat-type tail parachute (drag coefficient approximately 0.73) with a 27.5-foot towline will be effective as an emergency spin-recovery device during demonstration spins of the airplane. The model results also indicate that the airplane will not tumble for any.loading condition indicated possible.
Lee, Henry A.↗
Chromospherically active stars. X - Spectroscopy and photometry of HD 212280
The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of about 0.15 mag and a mean period of 29.46 days. Our V data were divided into 11 sets and in all but one case two spots were required to fit the data. Lifetimes of 650 days and a minimum of 1350 days have been determined for two of the four spots. The differential rotation coefficient of 0.05 is relatively small. The age of the system is about 1.9 X 10 exp 9 yrs. The G subgiant is rotating slower than pseudosynchronously while the F-type star is rotating faster.
Fekel, Francis C.↗
The 11 year history of starspots on V1149 Ori = HD 37824
All available radial-velocity measures, published and unpublished, yield an improved period and a new (assumed circular) solution. The period is 53.58 d +/- 0.02 d, and conjunction (K1 giant in front) was at 2 444 325.93 +/- 0.12 d. Eleven years of V-band photometry, published and unpublished, between 1978-1979 and 1989-1990 are analyzed. Eighteen data groups are fit with a two-spot light-curve-modeling technique. Six spots existing sometime during the 11 years are identified, and the 4-percent range of their rotation periods is used to estimate a differential rotation coefficient of k = 0.08 +/- 0.02. Observed lifetimes of those six spots are consistent with times calculated on the assumption that large spots are disrupted by the shear of differential rotation. The two best observed spots each lasted about five years.
Hall, Douglas S.↗
Experimental Investigation of Flow Condensation in Microgravity
Future manned missions to Mars are expected to greatly increase the space vehicle's size, weight, and heat dissipation requirements. An effective means to reducing both size and weight is to replace single-phase thermal management systems with two-phase counterparts that capitalize upon both latent and sensible heat of the coolant rather than sensible heat alone. This shift is expected to yield orders of magnitude enhancements in flow boiling and condensation heat transfer coefficients. A major challenge to this shift is a lack of reliable tools for accurate prediction of two-phase pressure drop and heat transfer coefficient in reduced gravity. Developing such tools will require a sophisticated experimental facility to enable investigators to perform both flow boiling and condensation experiments in microgravity in pursuit of reliable databases. This study will discuss the development of the Flow Boiling and Condensation Experiment (FBCE) for the International Space Station (ISS), which was initiated in 2012 in collaboration between Purdue University and NASA Glenn Research Center. This facility was recently tested in parabolic flight to acquire condensation data for FC-72 in microgravity, aided by high-speed video analysis of interfacial structure of the condensation film. The condensation is achieved by rejecting heat to a counter flow of water, and experiments were performed at different mass velocities of FC-72 and water and different FC-72 inlet qualities. It is shown that the film flow varies from smooth-laminar to wavy-laminar and ultimately turbulent with increasing FC-72 mass velocity. The heat transfer coefficient is highest near the inlet of the condensation tube, where the film is thinnest, and decreases monotonically along the tube, except for high FC-72 mass velocities, where the heat transfer coefficient is enhanced downstream. This enhancement is attributed to both turbulence and increased interfacial waviness. One-ge correlations are shown to predict the average condensation heat transfer coefficient with varying degrees of success, and a recent correlation is identified for its superior predictive capability, evidenced by a mean absolute error of 21.7%.
microgravity↗
Fabrication of Lightweight Radiation Shielding Composite Materials by Field Assisted Sintering Technique (FAST)
Advances in radiation shielding technologies are needed to protect humans and electronic components from all threats of space radiation over long durations. In this paper, we report on the use of the innovative and novel fabrication technology known as Field Assisted Sintering Technology (FAST) to fabricate lightweight material with enhanced radiation shielding strength to safeguard humans and electronics suitable for next generation space exploration missions. The base materials we investigated were aluminum (Al), the current standard material for space hardware, and Ultra-High Molecular Weight Polyethylene (UHMWPE), which has high hydrogen content and resistance to nuclear reaction from neutrons, making it a good shielding material for both gamma radiation and particles. UHMWPE also has high resistance to corrosive chemicals, extremely low moisture sensitivity, very low coefficient of friction, and high resistance to abrasion. We reinforced the base materials by adding high density (ie, high atomic weight) metallic material into the composite. These filler materials included: boron carbide (B4C), tungsten (W), tungsten carbide (WC) and gadolinium (Gd).
Prasad, Narasimha↗