Guentert, Donald C

Hatch, James E

Medeiros, Arthur A

English

NASA Technical Reports Server

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RESEARCH MEMORANDUM 
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*' P E R FORMANCE OF J35-A-2.3 COMPRESSOR 
I - OVER-ALL P ERFORMANCE CHARAC TERISTICS AT EQUIVALENT 
SPEEDS FROM 20 TO 100 PERCENT OF D E SIGN 
By A r thur A . Medeiros, Donald C. Guentert, and J ames E. H a tch 
Lewis F light Propulsion Laboratory 
Cleveland, Ohio 
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CLASSIFIED DCCUMENT 
This document contains classlfJed !nJorrnatlon affecting the National Defense of the United Slates within the 
meaning of the EspIonage Act, USC 50:31 and 32. Its transmission or the revelation of its contents in any 
manner to an unauthorized person Is pr oh1bited by law. 
Information so classified may be imparted only to persons in the military and naval services of the United 
States, appropriate civilian officers and employees of the Federal Government who have a legitimate interest 
therein, and to United Stales citizens of known loyally and discretion who of necessity must be Wormed thereof. 
NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
WASHINGTON 
October 1, 1951 
https://ntrs.nasa.gov/search.jsp?R=19930086610 2020-06-17T13:59:14+00:00Z

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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 
RESEARCH MEMORANDUM 
PERFORMANCE OF J35-A-23 COMPRESSOR 
I - OVER-ALL PERFORMANCE CHARACTERISTICS P!f EQUIVALENT 
SPEEDS FROM 20 TO 100 PERCENT OF DESIGN 
By Arthur A. Medeiros, Donald C. Guentert, and James E. Hatch 
SUMMARY 
An investigation of the over-all performance of the J35-A-23 
compressor was conducted as the preliminary step in an investi-
gation of surging and off-design performance of high-pres sure-ratio 
axial-flow compressors. The J35-A-23 compressor is a l6-stage com-
pressor designed to produce a total-pressure ratio of 8.75 at an 
equivalent flow of 155 pounds per second and an equivalent speed of 
6100 rpm. 
Tests were run over a range of flows at speeds from 20 to 100 per-
cent design speed. The maximum calculated total-pressure ratio 
obtained was 9.50 at an efficiency of 0.792 at an equivalent flow of 
157.7 pounds per second. The measured total-pressure ratio at this 
point was 9.78. Because the compressor was not operated to surge at 
design speed, this value may not represent the maximum obtainable. 
At the design pressure ratio of 8.75, the equivalent weight flow was 
158.4 pounds per second with an efficiency of 0.802 as compared with 
a design equivalent flow of 155 pounds per second and an assumed 
efficiency of '0.830. The maximum eff-iciency obtained was 0.835 at 
85 percent of design speed at an equivalent flow of 123.2 pounds per 
second. 
INTRODUCTION 
Improvement in the altitude performance and the economy of 
turbojet engines can be realized through the use of compressors pro-
ducing pressure ratios higher than those currently in use. Serious 
problems have been encountered, however, in surging and off-design 
performance of high-pressure-ratio compressors. As a preliminary 
RESTRICTED 
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step in an investigation of these problems, over-all performance tests 
have been made, with the cooperation of the U. S. Air Force and the 
Allison Division of General Motors Corporation, on a J35-A-23 axial-flow 
compressor of 16 stages designed to produce a total-pressure ratio of 
8.75 at an equivalent flow of 155 pounds per second and equivalent speed 
of 6100 rpm. 
Tests were run over a range of flows at speeds from 20 to 100 per-
cent of design. Because of power limitations, tests at design speed 
were run at an inlet pressure of 5.7 inches of mercury absolute. At 
speeds below design speed, the inlet pressure was adjusted so that the 
average Reynolds number relative to the first rotor-blade row was 
approximately 230,000 at all speeds. Speeds from 20 to 50 percent of 
design were run with room-air inlet temperature; speeds above 50 per-
cent of design were run with refrigerated air at a temperature of 
-55 0 F. 
APPARATUS AND INSTRUMENTATION 
Compressor 
Type 
Number of stages 
Design equivalent weight flow, pounds per second 
Design total-pressure ratio 
Design efficiency 
Design equivalent speed, rpm 
Tip diameter, inches 
Diameter ratio at first rotor inlet 
Diameter ratio at compressor discharge 
Driving Power 
Axial-flow 
16 
155 
8.75 
0.830 
6100 
33.5 
0.55 
0.90 
Drive motor 
Speed control 
Gear box 
9000-horsepower synchronous motor 
Variable frequency 
Power available at 6100 rpm 
Compressor pow'er required at 
design point with sea-level 
inlet conditions 
5.016 ratio double-helical speed 
increaser 
6100 horsepower 
28,220 horsepower 
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Installation and Instrumentation 
Air supply 
Exhaust 
Air Control 
Air metering 
Compressor inlet 
Compressor inlet pressure 
Compressor inlet temperature 
Compressor discharge pressure 
Compressor discharge temperature 
Compressor insulation 
Pressure measurement 
Temperature measurement 
Motor-speed measurement 
Atmospheric air or refrigerated air 
at pressure of 50 inches mercury 
absolute 
Altitude exhaust at 10 inches 
mercury absolute 
Butterfly throttles in inlet and 
outlet ducting 
Calibrated, adjustable, submerged 
orifice 
Depression tank 6 feet in diame~er 
and approximately 10 feet long 
Two wall static-pressure taps 
1800 apart and six total-pressure 
tubes located at area center of 
equal areas in depression tank 
Six shielded total-temperature 
probes located at area center of 
equal areas in depression tank 
Eight wall static-pressure taps 
spaced around Circumference, and 
16-tube circumferential total-
pressure rake surveyed over five 
equispaced radial positions I inch 
downstream of discharge guide 
vanes 
Four double stagnation-chamber 
thermocouple rakes spaced around 
the circumference with five equally-
spaced radial measuring stations 
located I inch downstream of 
discharge guide vanes 
At speeds above 50 percent of 
design7compressor insulated with 
2 inches of glass wool. No insu-
lation used below 50 percent of 
design speed 
Water and mercury manometers 
Calibrated potentiometer in con-
junction with spotlight 
galvanometer 
Electric chronometric tachometer 
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The precision of measurements is estimated to be within the follow-
ing limits: 
o Temperature, R. • . ••• 
Pressure, inches mercury 
Weight flow, percent 
Speed, percent •••••• 
RESULTS AND DISCUSSION 
• ±1.0 
. • . • . • • ±O. 05 
. . ±1.5 
• • • ±0.3 
The total-pressure ratio and the efficiency are presented in fig-
ure 1 as functions of equivalent weight flow at equivalent speeds of 
20 to 100 percent of design. Figures 2 and 3 are larger scale plots of 
the pressure ratio, with efficiency contours, as a function of equiva-
lent weight flow. At each flow point the discharge total pressure was 
obtained by two methods. The measured total pressure is the arithmetic 
average of the circumferential-rake measurements at five radial posi-
tions. The calculated total pressure was obtained by the method 
presented in reference 1. Adiabatic temperature-rise efficiencies were 
calculated using both pressures for the isentropic power input and the 
arithmetic average of the 20 discharge temperatures for the actual 
power input. The differences in the total-pressure ratios and effi-
ciencies obtained by the two methods are largest at the high-flow end 
of the curves ~nd are probably due to losses at the walls and in the 
blade wakes. 
At the design pressure ratio of 8.75, the equivalent weight flow 
was 158.4 pounds per second at an efficiency of 0.802 as compared with 
a design equivalent weight flow of 155 pounds per second and an 
assumed efficiency of 0.830. The maximum calculated pressure ratio 
obtained was 9.50 at an efficiency of 0.792 and an equivalent weight 
flow of 157.7 pounds per second. The measured total-pressure ratio 
at this point was 9.78. This value does not represent the maximum 
obtainable pressure ratio because the compressor was not surged at 
design speed. The maximum efficiency of 0.835 occurred at 85 percent 
of design speed at an equivalent weieht flow of 123.2 pounds per sec-
ond and a pressure ratio of 5.80. The peak efficiency dropped sharply 
at speeds below 82 percent of design to a value of 0.495 at 20 percent 
of design speed. 
Surge was encountered at all speeds above 20 percent of design 
with the exception of design speed where it was not thought advisable 
to surge the compressor and risk mechanical failure. At speeds from 
30 to 85 percent of deSign, the flow was decreased until the compressor 
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surged. A point was then taken at the flow and pressure ratio closest 
to surge at which stable compressor operation could be obtained. At 
85 percent of design speed incomplete data were obtained at the surge 
point beceuse the flow conditions changed enough while data were being 
taken to cause surge. The pressure ratio at this point is therefore 
based on the total pressure at the mean radius of the diffuser dis-
charge instead of the average compressor-discharge pressure. The 
surge-limit line has two distinct slopes - one for speeds up to 80 per-
cent of design and a steeper slope for speeds above 80 percent of 
design. 
SUMMARY OF RESULTS 
The following results were obtained from an investigation of the 
over-all performance of a J35-A-23 IS-stage axial-flow compressor: 
1. At the design pressure ratio of 8.75, the equivalent weight 
flow was 158.4 pounds per second with an efficiency of 0.802 as com-
pared with the design equivalent weight flow of 155 pounds per second 
and an assumed efficiency of 0.830. 
2. The maximum calculated total-pressure ratio was 9.50 at an 
efficiency of 0.792 and an equivalent weight flow of 157.7 pounds per 
second. The measured total-pressure ratio at this point was 9.78. 
3. The maximum efficiency of 0.835 occurred at 85 percent of 
design speed at an equivalent weight flow of 123.2 pounds per second 
and a pressure ratio of 5.80. 
Lewis Flight Propulsion Laboratory, 
National Advisory Committee for Aeronautics, 
Cleveland, Ohio. 
REFERENCE 
1. NACA Subcommittee on Compressors: Standard Procedures for Rating 
and Testing Multistage Axial-Flow Compressors. NACA TN 1138, 
September 1945. 
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20 1220 25 . 8 80 159, 
30 1830 25 . 8 80 237,300 
50 3050 16 . 6 80 249 , 100 
65 3965 8.8 - 55 236 , 300 
75 4575 7.7 50 232 , . 14 
80 4880 7 . 0 -50 220 , 
82 5002 6 . 9 -50 224, 
85 5185 6.6 -50 221, 
100 6100 5.7 - 50 211 , 
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Equivalent weigh t flow, lb/sec 
Figure 1 . - Over- all performance of J35- A-23 compressor. 
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Figure 2. - Performance characteristics of J35-A-23 compressor at low speeds. 
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Equivalent weight flow, lb/sec 
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Figure 3 . - Performance characteristics of J35-A-23 compressor at 
high speeds. 
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Performance of J35-A-23 Compressor I : Over-all Performance Characteristics at Equivalent Speeds from 20 to 100 Percent of Design

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