Showing papers on "Overpressure published in 1975"

Minimization of sonic-boom parameters in real and isothermal atmospheres

Abstract: The procedure for sonic-boom minimization introduced by Seebass and George for an isothermal atmosphere was converted for use in the real atmosphere by means of the appropriate equations for sonic-boom pressure signature advance, ray-tube area, and acoustic impedance. Results of calculations using both atmospheres indicate that except for low Mach numbers or high altitudes, the isothermal atmosphere with a scale height of 7620 m (25 000 ft) gives a reasonable estimate of the values of overpressure, impulse, and characteristic overpressure obtained by using the real atmosphere. The results also show that for aircraft design studies, propagation of a known F-function, or minimization studies at low supersonic Mach numbers, the isothermal approximation is not adequate.

Numerical simulation of regular and Mach reflections

Abstract: The results of an M∞=2 shock wave propagating in air down a shock tube and impinging on a wedge were calculated using both a two‐dimensional Eulerian code and a two‐dimensional Lagrangian code. The air was considered to be an ideal gas with γ=1.4. Both 2:1 and 1:2 wedges were used; these angles are known to generate regular and Mach reflected shock waves, respectively. The calculated results agreed quite well in both shock angle and overpressure with the appropriate theoretical or experimental results. A comparison of the two methods showed that the Eulerian calculation was easier and cheaper, gave equally good shock and expansion wave results, but ’’washed out’’ the slip line whose approximate position was still observable in the Lagrangian calculation.

Motor vehicle headlamp lens washer - has fluid released through multiple nozzles from high pressure warmed supply container

Abstract: The container is heated to a temp of over 50 deg. and has an overpressure of at least 5 atm. The reservoir is mutated in the flow circuit of the vehicle engine cooling fluid. Alternatively the reservoir can be heated by the vehicle exhaust gas. the overpressure is achieved by compressed air and the reservoir is thermally insulated. It is made from elastic, deformable material. The jets are operated by the driver by means of magnetically actuated valve, to spray directly onto lamp lenses.

Estimating External Blast Loads from Suppressive Structures

Abstract: : This report describes methods for predicting blast overpressure outside suppressive structures. Prediction curves are in scaled form. Data are compred to free-field data for large high-explosive detonations on the ground.

On Nuclear Height-of-Burst Airblast at High Overpressure

Abstract: : Results of a brief review and evaluation of height-of-burst (HOB) airblast environments produced by nuclear weapons, with emphasis placed on the high overpressure side of the thermal precursor shock envelope, are presented. It is concluded that no significant precursors will be formed at and above the 1000 psi overpressure level for any value of weapon yield or height-of-burst, and that blast environment prescriptions for ideal surfaces may be used with acceptable confidence for bursts over thermally non-ideal surfaces in this overpressure range. It is concluded further that no degradation in the values of airblast kill mechanisms with respect to ground burst values should occur over a substantial portion of the shins of the HOB curves at and above 1000 psi.

Capacitor cover plate with overpressure protection - has sealing plate with weakened points forcing plate into flexure under over-pressure

Abstract: The cover plate with an overpressure protection is intended for shearing off lead-in wires and similar connections in a capacitor under overpressure conditions in its housing. The arrangement contains a sealing plate with weakened points which actuate a flexing motion of the sealing plate under internal overpressure conditions. Preferably shearing blades are connected to the sealing plate whose flexing actuates the shearing off of the lead-in wire.

Quarry blast acoustic wave (concussion)—response of structures and human annoyance

Abstract: Quarry blasts were monitored during 1973–1974 at several locations in Southern Ontario to determine if the acoustic wave (concussion) was likely to be of significance from the points of view of structural damage and human annoyance. The monitoring instrumentation used included sonic boom microphone‐carrier system and FM tape recorder. The characteristics of the blast wave, overpressure, spectrum, and duration were analyzed using a storage oscilloscope and real‐time analyzer and were compared with the characteristics of sonic booms. The two phenomena were shown to be similar in spectral content to most energy in the infrasonic region; the overpressure at several thousand feet from a blast can be similar to that of a sonic boom, whereas the duration of the pressure perturbation is several times longer for a blast than for a sonic boom. It is concluded that damage and annoyance criteria developed from sonic boom research may reasonably be applied to quarry blasts. It was also found that in many instances the acoustic wave can be of greater significance than ground vibration induced by the same blast.

Prediction of sonic boom from experimental near-field overpressure data

Abstract: A computerized procedure for predicting sonic boom from experimentalnear-field overpressure data has been developed. The procedureextrapolates near-field pressure signatures for a specified flightcondition to the ground by ;the Thomas method. Near-field pressuresignatures are interpolated from a data bas.e of experimentalpressure signatures. 'The program is an independently operatedODIN (Optimal Design Integration) program which obtains flightpath information from other ODIN programs or from, input. .. •.-

Prediction of sonic boom from experimental near-field overpressure data. Volume 1: Method and results

Abstract: A computerized procedure for predicting sonic boom from experimental near-field overpressure data has been developed. The procedure extrapolates near-field pressure signatures for a specified flight condition to the ground by the Thomas method. Near-field pressure signatures are interpolated from a data base of experimental pressure signatures. The program is an independently operated ODIN (Optimal Design Integration) program which obtains flight path information from other ODIN programs or from input.