ISO 4679:2023

INTERNATIONAL ISO
STANDARD 4679
First edition
2023-06
Ships and marine technology —
Hydraulic performance tests for
waterjet propulsion system
Navires et technologie maritime — Essais de performance
hydraulique pour le système de propulsion hydrojet
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
4 Measurement and acceptance criteria . 3
4.1 General . 3
4.2 Measurement range . 4
4.3 Stable operating conditions of measuring systems . 4
4.4 E valuation of flow and head . 5
4.5 E valuation of efficiency or power . 5
5 Measurement uncertainty .6
5.1 General . 6
5.2 Statistical evaluation of overall measurement uncertainty . 6
5.2.1 E valuation of the random uncertainty . 6
5.2.2 E valuation of the systematic uncertainty . 6
5.2.3 Overall uncertainty . 7
5.2.4 Determination of overall uncertainty of efficiency . 7
5.3 Conversion . 8
5.3.1 Conversion to the guarantee conditions . 8
5.3.2 Translation of the test results. 8
6 Test method . 9
6.1 Test condition . 9
6.1.1 Test location . . 9
6.1.2 Test personnel . . 9
6.1.3 Test date . 9
6.1.4 Test outline . 9
6.1.5 Environment and water quality . . 9
6.2 Test device . 10
6.3 Test items . 10
6.3.1 General . 10
6.3.2 Performance test . 10
6.3.3 NPSH test . 11
7 Test report .11
Annex A (informative) Test report .12
Annex B (informative) Working section of the test device .15
Bibliography .18
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 8, Ship design.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
INTERNATIONAL STANDARD ISO 4679:2023(E)
Ships and marine technology — Hydraulic performance
tests for waterjet propulsion system
1 Scope
This document specifies the measurement and acceptance criteria and the test report of hydraulic
performance tests for waterjet propulsion system of Class A and Class B.
The test methods for the waterjet propulsion pump with and without the inlet duct are both specified.
This document is applicable to the hydraulic performance test of water jet propulsion under the
specified test conditions. This document specifies the precision grade of Class A for hydraulic model
tests of water jet propulsion and Class B for acceptance tests of small and middle-sized or intermediate
test models.
In addition, this document specifies the test conditions of Class A and Class B, and recommendations
and requirements for test equipment to ensure that the test can be carried out under the conditions of
corresponding accuracy.
This document does not include miscellaneous parts of waterjet unit, such as steering and reversing
gear, hydraulic system and control system.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
waterjet unit
unit that consists of waterjet propulsion system (3.2), steering and reversing gear, hydraulic system and
control system which is able to steer and reverse the main body
3.2
waterjet propulsion system
propulsion system that consists of waterjet pump (3.3), nozzle and inlet duct (generally the impeller of
waterjet pump is integrated with the nozzle) and that is able to drive the main body moving
3.3
waterjet pump
pump that transfers the energy of prime mover to water by rotating impeller
Note 1 to entry: The waterjet pump obtains a counter-acting force and drives the main body moving. It consists
of impeller, guide vane, shell and shaft (hereinafter referred to as “pump”). The main types are mixed-flow type
and axial flow type. The axial flow waterjet pump is one in which the liquid is discharged axially from the
impeller. The mixed-flow waterjet pump is one in which the liquid is discharged from impeller with an angle α (
09°<α <°0 ) to the shaft line, also called the inclined waterjet pump.
3.4
flow rate
Q
volume of liquid discharged by waterjet pump (3.3) per unit time
3.5
pump total head
H
algebraic difference between the outlet total head, H , and the inlet total head, H
2 1
Note 1 to entry: Pump total head is given by Formula (1):
HH=− H (1)
where
H is the inlet total head, expressed in Pa;
H is the outlet total head, expressed in Pa.
Note 2 to entry: Unless otherwise specified, the baseline of the head is the waterjet propulsion shaft line.
[SOURCE: ISO 9906:2012, 3.2.15, modified — notes 1 and 2 to entry have been modified.]
3.6
pump power input
P
power transmitted to the pump by its driver
[SOURCE: ISO 17769-1:2012, 2.1.11.2, modified — note 1 to entry has been deleted.]
3.7
pump efficiency
η
proportion of the pump power input (3.6), P, delivered as pump power output, P , at given operating
u
conditions
Note 1 to entry: Pump efficiency is given by Formula (2):
P
u
η= (2)
P
where
P is useful mechanical power transferred to the liquid during its passage through the pump, given
u
by Formula (3);
Pg=ρ QH (3)
u
[SOURCE: ISO 17769-1:2012, 2.1.12.1, modified — Formula (3) has been added and the symbols have
been explained.]
3.8
type number
K
dimensionless quantity, defined by Formula (4):
1 1
2 2
′ ′
2πnQ ωQ
K = = (4)
3 3
′ 4 ′ 4
()gH ()y
where
Q′ is volume flow rate per eye, expressed in m /s;
H′ is head of the first stage, expressed in m;
−1 −1
ω is expressed in time, like s , and n is expressed in 60 × min form.
Note 1 to entry: The type number should be taken according to the maximum diameter of the first stage impeller.
3.9
net positive suction head
NPSH
pump inlet total head above the head, equivalent to the vapour pressure per unit volume liquid, i.e.
pump inlet total head adds head equivalent to atmospheric pressure and subtracts head equivalent to
the vapour pressure
Note 1 to entry: Net positive suction head is calculated by Formula (5):
pp−
bv
NPSH=−Hz + (5)
1D
ρg
where
p
is (absolute) atmospheric pressure, expressed in Pa;
b
p
is (absolute) vapour pressure, expressed in Pa;
v
z
is height of impeller inlet, expressed in m.
D
[SOURCE: ISO 17769-1:2012, 2.1.5.5, modified — definition has been modified; the symbols have been
modified and the notes 2, 3 and 4 to entry have been deleted.]
3.10
guarantee point
operating performance of the pump which the supplier guarantees to be achieved under specified
conditions
[SOURCE: ISO 17769-1:2012, 2.1.13.2, modified — note 1 to entry has been deleted.]
4 Measurement and acceptance criteria
4.1 General
The basic parameters of the waterjet hydraulic performance tests directly obtained from the
measurement are flow rate, pressure, torque and speed of rotation. The derived parameters calculated
from the basic parameters are head, shaft power and efficiency. All of these parameters shall meet the
acceptance criteria specified in this clause.
Table 1 gives the acceptance level of pump head, flow rate, shaft power and efficiency. All acceptance
criteria are expressed as percentages of guarantee values. The test equipment shall meet the measuring
precision requirements. The measuring apparatus and their calibration should be confirmed. Both the
purchaser and manufacturer shall be entitled to have representatives present at all tests. The date of
the test shall be mutually agreed by the purchaser and manufacturer. Acceptance criteria shall meet the
requirements in Table 1 and if applicable, any agreements between the purchaser and manufacturer.
Table 1 — Acceptance criteria for Class A and Class B
Class A Class B
Quantity
% %
Flow rate ±1,5 ±2,0
Speed of rotation ±0,2 ±0,5
Torque ±1 ±1,4
Pump total head ±1 ±1,5
Pump power input ±1 ±1,5
Pump efficiency ±2,25 ±2,9
A guarantee point may be detailed in a written contract, a customer-specific waterjet performance
curve, or similar written and project specific documentation.
If not otherwise agreed upon between the purchaser and the manufacturer, the following should apply.
a) The acceptance grade should be in accordance with the grades given in Table 1.
b) Tests should be carried out on the test stand of the manufacturer’s works with clean, cold water,
using the methods and test arrangements specified in this document.
c) The waterjet performance should be guaranteed between the waterjet’s inlet connection and outlet
connection.
d) Pipe and fittings (bends, reducers, and valves) outside the waterjet are not a part of the guarantee.
The combination of manufacturing and measurement tolerances in practice necessitates the usage of
tolerances on tested values. The tolerances given in Table 1 take into account both manufacturing and
measurement tolerances.
The performance of a waterjet varies substantially with the nature of the liquid being pumped. Although
it is not possible to give general requirements and guidelines in which clean, cold water can be used to
predict performance with other liquids, it is desirable for the parties to agree on empirical rules to suit
the particular circumstances.
For batch products, the number of waterjets which are tested should be agreed between the purchaser
and manufacturer.
4.2 Measurement range
The flow rate is measured within the range of 80 % to 110 % of the best efficiency point or duty point at
identical speed of rotation.
The variation between the measured speed of rotation and specified speed of rotation should be
within ±20 % for Class A and the range from 60 % to 120 % for Class B.
4.3 Stable operating conditions of measuring systems
The test should be carried out on the test stand which meets the corresponding precision grade. The
test stand may be the manufacturer’s test works, or a test stand mutually agreed between the purchaser
and the manufacturer. The precision grade of the test equipment is decided by the measuring system.
The flow rate, inlet and outlet pressure, speed of rotation, torque, which are naturally fluctuating
when measured in the tests, as well as the signals, are automatically recorded or the statistical records
accumulate. The readings of delivered signals should satisfy the stable condition.
If the design or operation of the pump causes a large fluctuation in the measured value, a buffer device
may be installed in the measuring instrument or its connecting pipeline, to reduce the fluctuation
to the range given in Table 2 for measurement. Buffer devices should be symmetrical and linear, like
capillaries, which should provide integral values that contain at least one complete fluctuation period.
Table 2 — Permissible amplitude of fluctuation as a percentage of mean value of quantities
being measured
Permissible amplitude of fluctuations
Measured quantity
Class A Class B
% %
Flow rate ±2 ±3
Differential head ±3 ±4
Pressure ±2 ±3
Pump power input ±2 ±3
Speed of rotation ±0,5 ±1
Torque ±2 ±3
Temperature 0,3 °C 0,3 °C
Several sets of readings should be taken for each operating point considered. The arithmetic mean of
the mean values from all sets of readings for each quantity should be taken as the actual value given
by the test for the operating conditions considered. This actual value is used to ensure that the overall
tolerance of the measuring system meets the uncertainty requirement of the corresponding grade. A
minimum of three sets of readings should be taken at unequal intervals at the chosen point and the
mean value of each quantity and the efficiency derived from each set of readings should be recorded.
The variation of quantities shall meet the requirement of Table 3 (see ISO 5198).
Table 3 — Limits of variation between repeated mean values of the same quantity
(based on 95 % confidence limits)
Flow rate, pump total head, torque and pump power input Speed of rotation
Number of sets
of readings
% %
3 0,8 0,25
5 1,6 0,5
7 2,2 0,7
9 2,8 0,9
4.4 Evaluation of flow and head
Guarantee point evaluation should be performed at the rated rotational speed. It is not necessary to
recalculate the test points based on rotational speed in cases where the test rotational speed is identical
to the rated rotational speed. For tests in which the test rotational speed is different from the rated
rotational speed, each test point should be recalculated to the rated rotational speed, using the affinity
laws.
The acceptance criteria of flow rate should be applied to its guarantee point at the guarantee head, and
vice versa.
If there is no special requirement, the guarantee pump total head, H , is usually measured under the
G
condition of guarantee flow rate of Q . It shall meet the acceptance requirements that the absolute
G
value of the deviation between the head and the guarantee pump total head H is not greater than the
G
head tolerance value. If the purchaser and the manufacturer agree, the method of determining
guarantee flow rate, Q , under guarantee pump total head, H , may also be used.
G G
4.5 Evaluation of efficiency or power
If the efficiency or power has been guaranteed, it should be evaluated against the applicable acceptance
grade tolerance factor, i.e. the same as for QH/ in the following manner.
After a best-fit test curve (QH− / Q−η / or QP− curves) is drawn and smoothly fitted through the
measured test points, an additional str
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