NAqA- CR-191647 ONERA M6 wing, and (5) unsteadyflow of a compressible jet impinging on a ground p... more NAqA- CR-191647 ONERA M6 wing, and (5) unsteadyflow of a compressible jet impinging on a ground plane (with and without cross flow). The emphasisof the test caseswas validation of code,and assessment of performance, as well as demonstrationof flexibility.
A literature survey was conducted to review concepts previously proposed for reducing aerodynamic... more A literature survey was conducted to review concepts previously proposed for reducing aerodynamic skin friction, with ah emphasis toward reviewing those with potential for aircraft application. The four main concepts discussed are suction, gaseous injection, particle additives, and compliant wall. Each of these concepts has significantly reduced skin friction in experimental studies. Laminar flow control by suction on full-scale aircraft may offer sizable potential rewards; however, no significant experimental-development effort is currently being pursued. Previous practical knowledge attained in laminar flow-control flight studies should be extended to a flightexperimental-development program utilizing a large subsonic transport. Gaseous tangential slot injection offers an attractive potential at hypersonic speeds, where both large reductions in skin-friction drag and surface temperatures have been measured. Continuing efforts are underway to determine the effect of swept and multiple slots. The simplicity of the compliant wall concept (no internal hardware) makes it particularly appealing. Preliminary guidelines have been presented for the selection of compliant materials to match the test conditions in future studies. Future efforts with particle additives should concentrate on defining the basic mechanisms involved, and therein allow for selection of optimum size, density, and concentration of particles for the largest drag reduction. Tangential slot injection of these optimum particles should be the most feasible method.
Virginia Space Grant Consortium Upper Atmospheric Payload Balloon System, V_. It is a comprehensi... more Virginia Space Grant Consortium Upper Atmospheric Payload Balloon System, V_. It is a comprehensive overview covering launch activities, post-launch activities, experimental results, and future flight recommendations. It is maintained by the Project Manager.
The variational principle of Hamilton is applied to develop an analytical formulation to describe... more The variational principle of Hamilton is applied to develop an analytical formulation to describe the volume viscosity in fluids. The procedure described here differs from those used in the past in that a dissipative process is represented by the chemical affinity and progress variable ͑sometimes called "order parameter"͒ of a reacting species. These state variables appear in the variational integral in two places: first, in the expression for the internal energy, and second, in a subsidiary condition accounting for the conservation of the reacting species. As a result of the variational procedure, two dissipative terms appear in the Navier-Stokes equation. The first is the traditional volume viscosity term, proportional to the dilatational component of velocity; the second term is proportional to the material time derivative of the pressure gradient. Values of the respective volume viscosity coefficients are determined by applying the resulting volume-viscous Navier-Stokes equation to the case of acoustical propagation and then comparing expressions for the dispersion and absorption of sound. The formulation includes the special case of equilibration of the translational degrees of freedom. As examples, values are tabulated for dry and humid air, argon, and sea water.
Earth-orbiting objects, large enough to be tracked, have been surveyed for possible systematic de... more Earth-orbiting objects, large enough to be tracked, have been surveyed for possible systematic debris removal. Based upon the statistical collision studies of others, it was determined that objects in orbits approximately 1000 km above the Earth's surface are at greatest collisional risk. This study has identified Russian C-1B boosters as the most important target of opportunity for debris removal. Currently, more than 100 in tact boosters are orbiting the Earth with apogees between 950 km and 1050 km. Using data provided by Energia USA, specific information on the C-1B booster, in terms of rendezvous and capture strategies, has been discussed.
Wake vortex trajectories and strengths are altered radically by interactions with the ground '_ P... more Wake vortex trajectories and strengths are altered radically by interactions with the ground '_ Professor and Chairman, Mechanical Engineering and M¢cahanics Deparm_nt,
The proposed Mars sample return mISSIon will be completed using natural Martian resources for the... more The proposed Mars sample return mISSIon will be completed using natural Martian resources for the majority of its operations. The system uses the following technologies: In-Situ Propellant Production (ISPP), a methane-oxygen propelled Mars Ascent Vehicle (MA V), a carbon dioxide powered hopper, and a hydrogen fueled balloon system (large balloons and small weather balloons). The ISPP system will produce the hydrogen, methane, and oxygen using a Sabatier reactor. a water electrolysis cell, water extracted from the Martian surlace, and carbon dioxide extracted from the Martian atmosphere. Indigenous hydrogen will fuel the balloon systems and Iocally-dclivcd methane and oxygen will fuel the MAV for the return of a 50 kg sample to Earth. The ISPP system will have a production cycle of 800 days and the estimated overall mission length is 1355 days from Earth departure to return to low Earth orbit. Combining these advanced technologies will enable the proposed sample return mission to be executed with reduced initial launch mass and thus be more cost efficient. The successful completion of this mission will serve as the next step in the advancement of Mars exploration technology. • C" C • " TABLE OF CONTENTS INTERFACES 39 COST ANALYSIS 41 RISK ASSES~IENT 41 CONCLUSIONS 42 Phase 2 or Phase 3 or an Ares V derivative. After check-but, the interplanetary cruise stage will C• .• . •. . l execute a burn to provide the necessary hyperbolic transfer orbit to intercept Mars. The cruise stage will enter Mars orbit through an aerocapture operation and then commence EDL. The heavy landing mass currently exceeds the technology capability of Viking derived decelerators. EDL will require the use of an inflatable aerodynamic decelerator (lAD), currently being developed at NASA Langley Research Center, to deploy and initially slow the vehicle in the thin atmosphere. After the vehicle has reached subsonic speeds, a ring sail parachute deploys and the lAD will be discarded. In the final phase of EDL the lander will separate from the parachute and descend to the surface under rocket power [2]. Upon confirmation of a successful landing, the lander will begin systems checks and commence surface operations. The surface operations CONOPS are depicted in Figure . sIc Bus* (kg) 2100 C&DH (kg) 114 Thermal (kg) 162 Balloon System (kg) 2014 ISPP (kg) 1500 C02 Hopper (kg) 350 MAV(kg) 80 Margin (kg) 15% *Includes 815 kg Entry System Flight Element Total (kg) 7268 ',,-,.0 '" 'L••"c-j re.r Vl-l .c ~= ~.4-~15 a~~B.29 ",.~~.
Computational analysis of two 1911 Wright brothers " Bent End " wooden propeller reproductions ha... more Computational analysis of two 1911 Wright brothers " Bent End " wooden propeller reproductions have been performed and compared with experimental test results from the Langley Full Scale Wind Tunnel. 1 The purpose of the analysis was to check the consistency of the experimental results and to validate the reliability of the tests. This report is one part of the project on the propeller performance research of the Wright "Bent End" propellers, intend to document the Wright brothers' pioneering propeller design contributions. Two computer codes were used in the computational predictions. The FLO_MG Navier-Stokes code 2 is a CFD code based on the Navier-Stokes Equations. It is mainly used to compute the lift coefficient and the drag coefficient at specified angles of attack at different radii 3. Those calculated data are the intermediate results of the computation and a part of the necessary input for the Propeller Design Analysis Code 4 (based on Adkins and Libeck method), which is a propeller design code used to compute the propeller thrust coefficient, the propeller power coefficient and the propeller propulsive efficiency. Nomenclature x, y, z = physical direction x,_, z, = the coordinate of the leading edge at the physical domain x,=, z,¢ -the coordinate of the trailing edge at the physical domain .
different approach for calibrating hot-wires, which simplifies the calibration procedure and redu... more different approach for calibrating hot-wires, which simplifies the calibration procedure and reduces the tunnel run-time by an order of magnitude was sought. In general, it is accepted that the directly measurable quantities in any flow are velocity, density, and total temperature. Very few facilities have the capability of varying the total temperature over an adequate range. However, if overheat temperature parameter, a w , is used to calibrate the hot-wire then the directly measurable quantity, voltage, will be a function of the flow variables and the overheat parameter i.e., E-f(u,p,a w ,T w ) where a w will contain the needed total temperature information. In this report, various methods of evaluating sensitivities with different dependent and independent variables to calibrate a 3-wire hot-wire probe using a constant temperature anemometer (CTA) in subsonic/transonic flow regimes is presented. The advantage of using a w as the independent variable instead of total temperature, T 0 , or overheat temperature parameter, T, is that while running a calibration test it is not necessary to know the recovery factor, the coefficients in a wire resistance to temperature relationship for a given probe. It was deduced that the method employing the relationship E = f(u,p,a w ) should result in the most accurate calibration of hot wire probes. Any other method would require additional measurements. Also this method will allow calibration and determination of accurate temperature fluctuation information even in atmospheric wind tunnels where there is no ability to obtain any temperature sensitivity information at present. This technique greatly simplifies the calibration process for hot-wires, provides the required calibration information needed in obtaining temperature fluctuations, and reduces both the tunnel run-time and the test matrix required to calibrate hot-/ wires. Some-of.the.results using the above techniques are presented in an appendix.
We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint ... more We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy.
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Papers by ROBERT ASH