Engineering topics

Burton, R. A.

Publications and source records attributed to Burton, R. A..

6 records

NASA NTRS1979

Observation of self-excited wobble in face seals

A face seal model consisting of a rigidly mounted rotor and a flexibly mounted stator was tested under conditions of eccentric loading. Self-excited oscillations in the form of combined precession and nutation of the stator were observed. The nature of the motion and its frequency are dependent on rotational speed, seal clearance, and external tilting moment. It is possible that some unexplained seal failures and waviness of seal faces are the result of such self excited wobble.

Etsion, I.↗

NASA NTRS1978

The thermoelastic patch contact problem for large Peclet number

An equation in the form of a Fourier series was derived in an earlier study to give displacements of the originally straight edge of a plate as the result of a small heat input patch moving at speed c along that edge. That unwieldly formulation is reduced to a simple integral equation, which is shown to be manageable in an example calculation. The integral equation is shown to be closely related to that of Ling and Mow, although it is much simpler to use. Comparison of the results of the simplification to results of the original series formulation suggest that the equation proposed for 'high Peclet number' may be a valid approximation for Peclet number as low as 2.5.

Kilaparti, S. R.↗

NASA NTRS1978

Thermoelastic effects in frictionally heated line contact of slablike bodies

Many sealing configurations incorporate the geometry of line contact on bluff, slablike bodies. When sliding speed is sufficiently high along or across the line of contact, instabilities may arise from interactions of thermal expansion, elastic deformation and frictional heating. These lead to concentrated contact with elevated temperatures and pressures. Previous studies have been largely restricted to two-dimensional models of such contact. The present study shows how those earlier results must be modified to apply to the more realistic geometry, and show also that the principal features of the interactions are the same in both geometries.

Heckmann, S. R.↗

NASA NTRS1976

Pressure distribution for patchlike contact in seals with frictional heating, thermal expansion, and wear

Sliding contact in seals is known to change at high sliding speed from initially uniform pressure to a deformed state where contact is restricted to small patches of the surface. An earlier analysis of such contact was based upon the assumption of uniform pressure on the small patches. The present study draws upon a thermoelastic influence function to provide simultaneous equations for pressure on subdivisions of the patches. The final result is that at high wear rate (and, consequently, high traversal speed of the patch along the surface of the more conductive body of the contacting pair) the pressure distribution becomes roughly triangular with the maximum pressure toward the leading edge of the patch.

Kilaparti, S. R.↗

NASA NTRS1975

Modeling of turbine blade tip contact

A mathematical model is developed to evaluate a number of physical effects in turbomachine blade tip contact on the basis of a broad brush approach to provide insights without undue complexity. The analysis is restricted to the case of a shoe encountering a moving blade row and pressing against it with a fixed time-average force. Relative displacement components in the contact region are identified and determined. Two key equations are derived, where it is shown that wear rate plays a strong role in determining the traversal speed of the contact patch. The formula for estimating the size of the contact patch shows that the higher the traversal speed is, the wider is the contact patch.

Burton, R. A.↗

NASA NTRS1974

Navy participation in the development of airframe parameter identification techniques

The Navy is currently involved in the development of advanced parameter identification techniques for use in aircraft flight testing and refinement of aircraft dynamic systems modeling. An overview is presented of the Navy's research programs, capabilities, and facilities. The use of parameter identification techniques are related to the flight testing, development, and simulation of aircraft and aircraft systems in the areas of flying qualities, automatic flight controls, flight dynamics, and advanced landing systems. Preliminary analytical and flight test results are presented. The impact that new parameter identification technology has on Navy flight test philosophy is discussed. Future plans are outlined.

Burton, R. A.↗