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Results for “lateral force”

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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Experimental investigation of lateral forces induced by flow through model labyrinth glands

The lateral forces induced by flow through model labyrinth glands were investigated. Circumferential pressure distributions, lateral forces and stiffness coefficients data obtained are discussed. The force system is represented as a negative spring and a tangential force orthogonal to eccentricity. The magnitude of these forces are dependent on eccentricity, entry swirl, rotor peripheral velocity and seal size. A pressure equalization chamber at midgland tests should in significantly reduced forces and stiffness coefficients.

Leong, Y. M. M. S.↗
NASA NTRS1978

Lateral forces induced by a misaligned roller

The magnitude of the lateral force induced by a roller, misaligned in its direction of travel is considered. Consequences of the induced lateral forces and examples of wheel suspension designs are given.

Mcginness, H.↗
NASA NTRS1984

Tropical response to lateral forcing with a latitudinally and zonally nonuniform basic state

The dynamics of lateral forcing of a stable tropical atmosphere by incident waves from the midlatitudes are examined. Attention is focused on conditions where the WKB method is invalid, and only given to barotropic flows. The tropical atmosphere is treated as a steady planetary wave and a zonal shear flow. The 200 mb level is investigated in terms of a midlatitude wave with self-compatible parametric values that is constrained to satisfy the radiation conditions at the boundary. Wave modes are found to be susceptible to trapping between two turning points in the equatorial zone in the presence of a zonal shear flow. Quasi-resonant waves can then appear over a wide range of parametric conditions of the forcing wave and the basic state. The zonal wind structure determines the resonance conditions.

Wilson, J. D.↗
NASA NTRS1992

Robotic Gripper Resists Torsion And Lateral Forces

Gripper for end effector of robot shaped to tolerate large initial misalignments with object gripped. Gripping surfaces contoured to prevent lateral forces from prying them apart. Ridges on handle mate with grooves in finger. Same ridge-end-slope pattern appears on opposite face of handle so two opposed fingers grip it.

Voellmar, George M.↗
NASA NTRS1989

Influence of impeller and diffuser geometries on the lateral fluid forces of whirling centrifugal impeller

Lateral fluid forces on two-dimensional centrifugal impellers, which whirl on a circular orbit in a vaneless diffuser, were reported. Experiments were further conducted for the cases in which a three-dimensional centrifugal impeller, a model of the boiler feed pump, whirls in vaneless and vaned diffusers. The influence of the clearance configuration between the casing and front shroud of the impeller was also investigated. The result indicated that the fluid dynamic interaction between the impeller and the guide vanes induces quite strong fluctuating fluid forces to the impeller, but nevertheless its influence on radial and tangential force components averaged over a whirling orbit is relatively small.

Ohashi, Hideo↗
NASA NTRS1990

Lateral restoring force on a magnet levitated above a superconductor

The lateral restoring force on a magnet levitated above a superconductor is calculated as a function of displacement from its original position at rest using Bean's critical-state model to describe flux pinning. The force is linear for small displacements and saturates at large displacements. In the absence of edge effects the force always attracts the magnet to its original position. Thus it is a restoring force that contributes to the stability of the levitated magnet. In the case of a thick superconductor slab, the origin of the force is a magnetic dipole layer consisting of positive and negative supercurrents induced on the trailing side of the magnet. The qualitative behavior is consistent with experiments reported to date. Effects due to the finite thickness of the superconductor slab and the granular nature of high-Tc materials are also considered.

Davis, L. C.↗
NASA NTRS2013

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

Cordova, Luis↗
NASA NTRS2014

Ground Contact Modeling for the Morpheus Test Vehicle Simulation

The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

Cordova, Luis↗
NASA NTRS1959

An Investigation of the Performance of Various Reaction Control Devices

An investigation of a small-scale reaction control devices in still air with both subsonic and supersonic internal flows has shown that lateral forces approaching 70 percent of the resultant force of the undeflected jet can be obtained. These results were obtained with a tilted extension at a deflection of 40 deg. The tests of tilted extensions indicated an optimum length-to-diameter ratio of approximately 0.75 to 1.00, dependent upon the deflection angle. For the two geometric types of spoiler tabs tested, blockage-area ratio appears to be the only variable affecting the lateral force developed. Usable values of lateral force were developed by the full-eyelid type of device with reasonably small losses in the thrust and weight flow. Somewhat larger values of lateral force were developed by injecting a secondary flow normal to the primary jet, but for conditions of these tests the losses in thrust and weight flow were large. Relatively good agreement with other investigations was obtained for several of the devices. The agreement of the present results with those of an investigation made with larger-scale equipment indicates that Reynolds number may not be critical for these tests. In as much as the effects of external flow could influence the performance and other factors affecting the choice of a reaction control for a specific use, it would appear desirable to make further tests of the devices described in this report in the presence of external flow.

Hunter, Paul A.↗
NASA NTRS1954

Experimental investigation of the forces and moments due to sideslip of a series of triangular vertical and horizontal tail combinations at Mach numbers

An experimental investigation was made at Mach numbers of 1.62, 1.93, and 2.41 of a series of tail combinations consisting of triangular vertical tail attached symmetrically to a triangular horizontal tail to determine the lateral force, yawing moment, and rolling moment due to sideslip. The apex angles of both the vertical- and horizontal-tail surfaces were varied systematically in order to obtain results for an appreciable range of operating conditions. The results of the investigation indicated that, for tails having subsonic leading edges and supersonic trailing edges, the lateral-force derivative and the yawing-moment derivative were predicted satisfactorily by the method presented in NACA TN 3071 except when the leading edges approach a sonic condition. The theoretical rolling-moment derivative was in fair agreement with the experimental derivative. For the limited tests in which both the leading and trailing edges were supersonic, the prediction of the lateral-force derivative and the yawing-moment derivative obtained from NACA TN 2412 was in good agreement with the experimental derivatives, whereas the prediction of the rolling-moment derivative was fair.

Coletti, Donald E↗
NASA NTRS1980

Flow Induced Spring Coefficients of Labyrinth Seals for Application in Rotor Dynamics

Flow induced aerodynamic spring coefficients of labyrinth seals are discussed and the restoring force in the deflection plane of the rotor and the lateral force acting perpendicularly to it are also considered. The effects of operational conditions on the spring characteristics of these components are examined, such as differential pressure, speed, inlet flow conditions, and the geometry of the labyrinth seals. Estimation formulas for the lateral forces due to shaft rotation and inlet swirl, which are developed through experiments, are presented. The utilization of the investigations is explained and results of stability calculations, especially for high pressure centrifugal compressors, are added. Suggestions are made concerning the avoidance of exciting forces in labyrinths.

Benckert, H.↗