Experimental Flow Models for SSME Flowfield Characterization

Full scale flow models with extensive instrumentation were designed and manufactured to provide data necessary for flow field characterization in rocket engines of the Space Shuttle Main Engine (SSME) type. These models include accurate flow path geometries from the pre-burner outlet through the throat of the main combustion chamber. The turbines are simulated with static models designed to provide the correct pressure drop and swirl for specific power levels. The correct turbopump-hot gas manifold interfaces were designed into the flow models to permit parametric/integration studies for new turbine designs. These experimental flow models provide a vehicle for understanding the fluid dynamics associated with specific engine issues and also fill the more general need for establishing a more detailed fluid dynamic base to support development and verification of advanced math models

A quantification of hydrodynamical effects on protoplanetary dust growth

Context. The growth process of dust particles in protoplanetary disks can be modeled via numerical dust coagulation codes. In this approach, physical effects that dominate the dust growth process often must be implemented in a parameterized form. Due to a lack of these parameterizations, existing studies of dust coagulation have ignored the effects a hydrodynamical gas flow can have on grain growth, even though it is often argued that the flow could significantly contribute either positively or negatively to the growth process. Aims. We intend to provide a quantification of hydrodynamical effects on the growth of dust particles, such that these effects can be parameterized and implemented in a dust coagulation code. Methods. We numerically integrate the trajectories of small dust particles in the flow of disk gas around a proto-planetesimal, sampling a large parameter space in proto-planetesimal radii, headwind velocities, and dust stopping times. Results. The gas flow deflects most particles away from the proto-planetesimal, such that its effective collisional cross section, and therefore the mass accretion rate, is reduced. The gas flow however also reduces the impact velocity of small dust particles onto a proto-planetesimal. This can be beneficial for its growth, since large impact velocities are known to lead to erosion. We also demonstrate why such a gas flow does not return collisional debris to the surface of a proto-planetesimal. Conclusions. We predict that a laminar hydrodynamical flow around a proto-planetesimal will have a significant effect on its growth. However, we cannot easily predict which result, the reduction of the impact velocity or the sweep-up cross section, will be more important. Therefore, we provide parameterizations ready for implementation into a dust coagulation code.Comment: 9 pages, 6 figures; accepted for publication in A&A; v2 matches the manuscript sent to the publisher (very minor changes

An investigation in the NASA MSFC 14-inch trisonic wind tunnel to determine the pressure distribution over the components of a 0.004 scale version of the Rockwell MCR 0074 baseline shuttle ascent configuration (IA32F), volume 3

For abstract, see N76-11223

Aerodynamic static stability and control effectiveness of a parametric shuttle launch configuration

Experimental aerodynamic investigations were conducted in the NASA/MSFC 14-inch Trisonic Wind Tunnel on a 0.004-scale model of the NR ATP baseline Shuttle launch configuration. The test model consisted of the NR ATP baseline orbiter, external tank, and SRB's with nozzles. Six component aerodynamic force and moment data were recorded over an angle of attack range from minus 10 deg to 10 deg at zero degrees sideslip and angle of sideslip range of minus 10 deg to 10 deg at zero angle of attack for a Mach range of 0.6 to 4.96. Rudder flare was constant at 10 deg during the entire test. The purpose of the test was to define the performance, stability, and control characteristics of the launch configuration as well as to investigate the buildup effect of two geometrical parameters

Aerodynamic characteristics of a 0.00563 scale 142-inch diameter solid rocket booster (MSFC model 449 and 480) with side mounted stings in the NASA/MSFC 14-inch trisonic wind tunnel (SA14FA)

An experimental investigation (SA14FA, TWT 620) was conducted in the MSFC 14-inch Trisonic Wind Tunnel (TWT) to determine the entry static stability of a 0.00563 scale shuttle solid rocket booster (SRB). The primary objective was to determine the effects of four side mounted sting configurations and to improve the definition of the aerodynamic characteristics in the vicinity of the SRB entry trim point. Data were obtained for two 60 and two 90 degree side mounted stings and a straight nose mounted sting. The angle of attack range for the side-mounted stings was 100 to 170 degrees while that for the nose mounted sting was 150 to 170 degrees. The Mach number range consisted of 0.6 to 3.48. Except for the aft attach ring, no protuberances were considered and the side slip and roll angles were zero. The test model was scaled from the 142-inch diameter SRB known as configuration 139 which was used during test TWT 572 (SA5F)

Space shuttle: Aerodynamic stability, control effectiveness and drag characteristics of a shuttle orbiter configuration at Mach numbers from 0.6 to 4.96

Experimental aerodynamic investigations were conducted in the NASA/MSFC 14-inch Trisonic Wind Tunnel from Sept. 27 to Oct. 7, 1972 on a 0.004 scale model of the NR ATP baseline shuttle orbiter configuration. Six component aerodynamic force and moment data were recorded at 0 deg sideslip angle over an angle of attack range from 0 to 20 deg for Mach numbers of 0.6 to 4.96, 20 to 40 deg for Mach numbers of 0.6, 0.9, 2.99, and 4.96, and 40 to 60 deg for Mach numbers of 2.99 and 4.96. Data were obtained over a sideslip range of -10 to 10 deg at 0, 10, and 20 deg angles of attack over the Mach range and 30 and 50 deg at Mach numbers of 2.99 and 4.96. The purpose of the test was to define the buildup, performance, stability, and control characteristics of the orbiter configuration. The model parameters, were: body alone; body-wing; body-wing-tail; elevon deflections of 0, 10, -20, and -40 deg both full and split); aileron deflections of plus or minus 10 deg (full and split); rudder flares of 10 and 40 deg, and a rudder deflection of 15 deg about the 10 and 40 deg flare positions

Aerodynamic roll characteristics of a 0.00548 scale 146-inch solid rocket booster reentry configuration (MSFC Model Number 486) over a portion of the reentry flight regime in the NASA MSF 14-inch trisonic wind tunnel

An experimental investigation was conducted in the MSFC 14 inch TWT to study the roll characteristics of a 0.00548 scale model of the 146 inch shuttle solid rocket booster to obtain more accurate rolling moment data on the solid rocket booster. A sensitive single component roll balance was utilized. Data were obtained for a single nose mounted sting. The angle of attack range consisted of angles from 150 deg to 190 deg; roll angles consisted of angles from 0 deg to 337 1/2 deg in increments of 22 1/2 deg; and Mach numbers were 1.46, 1.96, 2.74 and 2.48

Two-Source Dispersers for Polylogarithmic Entropy and Improved Ramsey Graphs

In his 1947 paper that inaugurated the probabilistic method, Erd\H{o}s proved the existence of $2\log{n}$-Ramsey graphs on $n$ vertices. Matching Erd\H{o}s' result with a constructive proof is a central problem in combinatorics, that has gained a significant attention in the literature. The state of the art result was obtained in the celebrated paper by Barak, Rao, Shaltiel and Wigderson [Ann. Math'12], who constructed a $2^{2^{(\log\log{n})^{1-\alpha}}}$-Ramsey graph, for some small universal constant $\alpha > 0$. In this work, we significantly improve the result of Barak~\etal and construct $2^{(\log\log{n})^c}$-Ramsey graphs, for some universal constant $c$. In the language of theoretical computer science, our work resolves the problem of explicitly constructing two-source dispersers for polylogarithmic entropy

An investigation to determine the pressure distribution on the 0.0137 scale solid rocket booster forebody (MSFC model 467) at angles of attack at or near 90 deg and high Reynolds numbers in the MSFC High Reynolds Number Wind Tunnel (SA29F)

An aerodynamic investigation was conducted in the MSFC High Reynolds Number Wind Tunnel to determine the pressure distribution over the foresection of the current 146 inch diameter shuttle SRB. The test model consisted of a 0.0137 scale version of the SRB nose cone and a forward portion of the cylindrical body which was approximately 2.7 calibers in length. The pressure distributions are plotted as a function of longitudinal station ratioed to body diameter and circumferential location for each angle of attack and Mach number. A Reynolds number variation study was made for Mach numbers of 0.4 and 0.6 at an angle of attack of 270 deg and roll angle of 180 deg