UNCLASSIFIED · This range of cam speeds is obtained from the speedranger output shaft speeds of 15 to RPM and a 5' to 1 worm gear ratio in conjunction with three gear- train-ratios

j i I

UNCLASSIFIED

ßepAaduced

lui ike

UNCLASSIFIED

NOTICE: When government or other drivings, speci¬

fications or other data are used for any purpose

other than in connection with a definitely related

government procurement operation, the U. S.

Government thereby incurs no responsibility, nor any

obligation whatsoever; and the fact that the Govern¬

ment may have formulated, furnished, or in any way

supplied the said drawings, specifications, or other

data is not to be regarded by implication or other¬

wise as in any manner licensing the holder or any

other person or corporation, or conveying any rights

or permission to manufacture, use or sell any

patented invention that may in any way be related

thereto.

MATERIAL LABORATORY NEW YORK NAVAL SHIPYARD

BROOKLYN 1, NJW YORK

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A S 1 I A

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DEVELOPMENT REPORT ON

A MEA.N5 OF MONITORING LABORATOEï EXPOSURES

TO INTENSE THERMAL RADIATION IN ACCORDANCE

WTH THE GENERALIZED FIELD PULSE

Labe Project ï>Oh.6-2, Part 12

FEB ï 0 1955

Final Report NS O8I-OOI

Technical Objective AW-7 AFS'^P-81|3

Jefferson A0 Carter

Optics and Nucleonics Branch

J,M. McGREEVY, Head

Superintending Engineer

GEO. J. DASHEFSKY

The Director

CAPT. A. B. JONESj Jr,, USN

NAVAL MATERIAL LABORATORY

New York Naval Shipyard

Brooklyn lÿ New York

ATOMIC ENERGY ACT OF I946 VW.'- W

CONFIDENTIAL RESTRICTED DATA

Lab. Project 501).6-2, Pt. 12 Final Report

CONTENTS

Page

AMINISTRATIVE INFIRMATION 3

INTRODUCTION ^

DESCRIPTION OF PULSE MECHANISM ^

ANALYSIS 7

CONaUSIONS 9

FIGURES

1 - Laborato.ry Simulated Field Pulse Mechanism - Photo L-I60OO-I

2 - Driving Mechanism for Laboratory Simulated Field Pulse Assembly Photo L-16000-2 J

3 ~ Photo^1^16^0^3°Labora'bor^ Simula ted-Field-Pulse Mechanism

ll - Control and Monitoring Panel for Laboratory Simulated Field Pulse Mechanism - Photo L-lóÔOO-l)

5 - Normalized Laboratory and Field Pulse Shapes

BIBLIOGRAPHY

2


ATOMIC ENERGY ACT OF 1946


Lab. Project 50116-2., Pt. 12

Final Report

ADMINISTRATIVE INFORMATION

1. This project has been conducted as part of the program originally

proposed by COMNYKNAVSHIPYD (Material Laboratory) confidential letter

S99/L5, Ser 960-92 of lit March 1950 and formally approved by Bureau

of Ships speedletter S99-(0)-(3li8), Ser 3¡48-75 of 6 April 1950, The

Naval Material Laboratory's thermal radiation program is under the

sponsorship of the Armed Forces Special Weapons Project.

2. This project was planned and executed under the general direction of

T. I. Monahan, Supervisor of the Optics Section.

INTRODUCTION

3» Most studies to date at the Naval Material Laboratory on the effects

of intense thermal radiation on materials have utilized either stationary

exposures,, employing rectangular pulses, or dynamic exposures in which

the time dependence of irradiance is essentially Gaussian.1 It is not

possible always to predict the behavior of organic materials, when

exposed to a nuclear detonation, on the basis of exposures to either of ‘

these laboratory sources, because of the evolution of smoke and volatile

products which can not be represented mathematically. The Naval Material

Laboratory has undertaken the development of a laboratory source in which

the irradiance is monitored in accordance with the normalized variation

of intensity of irradiation with time for a nuclear detonation. 'Thai ):




Lab. Project $Ok6-2s Pt, 12 Final Report

normalized fiield pulse is characterized by the irradiance rising to

maximum value at a timej called t,,,^, and then falling exponentially to

a value of h per cent of the maximum value at a time equal to lOt^.

DESCRIPTION OF PULSE MECHANISM

iu The basic exposure mechanism for the laboratory simulated field

pulse is a standard 2b inch carboneare signalling searchlight, shown as

part (a) in Figure (1). The searchlight beam pattern has been altered

by substituting a first surface ellipsoidal mirror, part (b) of

Figure (1), for the standard paraboloidal reflector, which has a sec¬

ondary focus at a distance of 55+1 inches in front of the ellipsoidal

mirror.

5» The manual signalling lever was replaced with a 30-tooth, lii|-degree,

Ig-inch pitch diameter steel spur gear, |art (c) of Figure (1), which

serves as the rotary coupling for driving the signalling shutter or

attenuator, part (d) of Figure (1)„ The attenuator or signalling shutter

is a radia] venetlan-blind-type unit, with long tapered flat blades that

normally overlap in the vertical dosed shutter plane position.

6. Ä precision cut cam, part (a) of Figures (1) and (2), which is rigidly

coupled to the signalling shutter spur gear by a steel rack, part (f) of

Figures (1) and (2), feeds the pulse shape information to the attenuator

through a spring loaded cam follower, part (g) of Figures (1) and (2).

b CONFIDENTIAL RESTRICTED DATA



Lab0 Project 501).6-2^ pte 12 Final Report

The radii of the pulse shape cam are based on the following calculationss

X A - B = A - C(Cos0)

A A

ediere T-^ = transmittance or relative irradiance at time ?!ttf from normalized field p’olss

A ” mean center line distance between b'j.ades

B “ mean projected width of shutter blades at rotation position "Q"

and & angle blades make with vertical or normally closed shutter plane«


ATOMIC ENERGY ACT OF 19½


Lab. Project 50i|6-2, pt. 12. Pinal Report

= 2

A(1 - Tx) then cos /9 =

17 G

and

where - change in pulse cam radius

and D - pitch diameter of signalling shutter spur gear.

7o The pulse shaPe cajn is drlven 'ey a geared down I/J4-H.P. speedranger

motor, part (h) of Figures (1) and (2), through a gear system, part (i)

of Figures (1) and (2), which gives continuously variable cam speeds of

1.3ÍI through 23.3 HPM. This range of cam speeds is obtained from the

speedranger output shaft speeds of 15 to RPM and a 5' to 1 worm gear

ratio in conjunction with three gear- train-ratios of 70/27, $5/k2 and

30/67.

8. A ?-bj.ade cr knife shutter, operated in conjunction with the signalling

shutter and activated by a micro switch working off a timing cam, which is

concentric with the pulse shape cam, initiates and terminates the pulsed

exposure. The V-blade shutter which is solenoid operated is shown as part

(j) in Figure(l).

9. The pulse shape mechanism is operated from a control box, part (a)

°f (2)s whlch provides for a nearby automatic exposure cycles

depressing the speedranger start button activates one complete exposure

cycle and returns the mechanism to its original starting position. The



6


Lab« Project 501^0-2* Pt.0 12 Final Report

speedranger employed has a built-in electric brake which is activated

by a cam attached to the pulse shape cam and prevents overshooting of

the exposure cycle«

IO« A complete wiring diagram for laboratory simulated field pulse

mechanism is shown in Figure (3)0 The control and monitoring panel

is shown in Figure (l±)o

ANALISIS

lio An evaluation of the performance of the laboratory simulated field

pulse mechanism gave the following resultss at pulse cam speeds of 103

to 23 RPM., the times to pulse peaks«, were. G02 to 3®7 seconds with

pulse lengths,, of 2ci to hO secondso The irradiance at pulse cutoff

is 3 P®* cent of the peak irradiance value and the total radiant energy in

the normalized laboratory simulated field pulse shape 1 per cent greater

than the to uai radiant energy in the generalized field pulse shape«»

Successive exposures at any speedranger setting give times to pulse peaks

and pulse lengths that are reproducible with an accuracy of greater than

.7 per cent«

12« The peak irradiance obtained with this exposure system is 12 cal/cm^

sec over »n area Stmrn in diameter5 and .*-0 eai/cm^ sec over an area 17mm

in diameter without the searchlight doorglas3« Employing the doorglass*

part (K) of Figure (1), the peak Irradiance is attenuated by 10 to

per cents but this procedure has the advantage of stabilizing the arc




Lab. Project 50^6-2, pt, 12 Final Report

during long exposures. The peak irradiance of successive exposures is

reproducible within the range of the arc fluctuations, which is + 6

per cento

130 An analysis of laboratory pulse traces derived from exposures of

various copper disc calorimeters and radiometers to the pulse cam source

gave the follcving empirical expressions for the total radiant energy

in the laboratory simulated field pulse and the times to peak irradiance

as follows 2

Q = 0.216 Hofj

where Q = radiant energy (cal/cm2),

H0= peak irradiance (cal/cm2sec),

T= pulse length (sec),

and t = C„09hT, max ^5

'Aere tmax = time to peak irradiance of laboratory pulse (sec).

-A. A grapnical comparison of the normalized laboratory pulse shape with

“he normalized field pulse shape is shorn in Figure (5).

n n « t OpNJTDENTIAL RESTRICTED DATA


8


Lab. Project Ôh6-2s Pt. 12 Final Report

CONCLUSIONS

Ig.. jhe laboratory simulated field pulse mechanism has performed more

than satisfactorily during its numerous test runs and has also shown

that it is quite versatile and rugged in construction. The infrequent

adjustments to the mechanism are very simple to make and are of the order

of magnitude that if left unadjusted do not materially affect the operation

of the mechanism or the empirical expressions derived for the pulse.

16» Exposures of materials to the laboratory simulated field pulse have

shown the need of additional units that will generate times to peak

irradiances somewhat less than now obtainable and also peak irradiances

somewhat greater than presently obtained. With these factors the basis,

the Naval Material Laboratory is presently constructing an additional

unit identical to the existing mechanism but with faster cam speeds to

cover a range of umax from 0.1^ to 2.3 seconds. The Material Laboratory

is also modifying the pulse generating mechanism for adoption to the

36 inch parabolic carbon-arc source for obtaining higher peak irradiances

at the t range of 0.15> to 2.3 seconds. IÏÏclX.

Appro ve eu


9 ATOMIC ENERGY ACT OF I9H6s bas

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D IS TR I BUT I ON LIST No. 100

Thermal Radiation Reports (Research)

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California Forest and Range Experimental Station, U.S. Forest Service, P0 Box 245, Berkeley, California ATTN: W.L.Fons, Division Forest Fire Research

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Mr. A. A. Brown, Chief, Fire Research Division, Forest Service. USDA, Washington 25, D.C.

Technical Operations Inc., 6 Schouler Court, achusetts ATTN: Dr. Frederick C. Henriques

Ar I ington Mass-

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^CLASSIFIED