Obviously, the influence of two items (a) and (c) is too great, and necessary
adjustments are needed, otherwise the deviation of combustion pressure will
certainly exceed the allowable deviation.
If n Æ Dn ¼ 0:28 1 Æ 4%
ð
Þ is used, the corresponding deviation of combustion pressure is Æ1:5%.
If a T Æ Da T ¼ 0:00282 1 Æ 3%
ð
Þ is used, the corresponding deviation of
combustion pressure is Æ1:3%.
After adjustment, the order of main parameter deviation and its influence on
combustion pressure deviation is as follows:
(a) The relative manufacturing accuracy of nozzle diameter and grain
diameter are still þ 1:3% and À0:13%, respectively, which still affects
the combustion pressure deviation d 1 ¼ À5:5%.
(b) The relative deviation Æ4% of the grain pressure index affects the
combustion pressure deviation d 2 ¼ Æ1:5%.
(c) The relative deviation Æ3% of the grain temperature sensitivity coefficient affects the combustion pressure deviation d 3 ¼ Æ1:3%.
The deviations of main parameters are eventually allocated and determined
by working nozzle design drawings and retarded grain development task
book.
(2) Computation of Combustion Pressure Comprehensive Deviation
Calculating criteria: It mainly depends on the combined effects of the
combustion pressure deviation d 1 caused by the relative manufacturing
accuracy of nozzle diameter and grain diameter, the combustion pressure
deviation d 2 caused by the relative deviation of grain pressure index, and the
combustion pressure deviation d 3 caused by the relative deviation of grain
temperature sensitivity coefficient.
Calculating method: In engineering practice, it should not only be considered
that the maximum of each deviation is unlikely to occur at the same time, and
that the three deviations are unlikely to overlap without compensation, but also
take into account the actual situation of small batch production and production
instability in the development process. Therefore, the three deviations should be
added up by statistics and multiplied by a certain coefficient as the comprehensive deviation of combustion pressure. The computational equation is
k ¼ 1:2
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
r 2
1 þ r 2
2 þ r 2
2
q
ð9:37Þ
where
k Combustion pressure comprehensive deviation;
d 1 Combustion pressure deviation caused by relative manufacturing accuracy of nozzle and grain diameter;
134
9 High-Temperature and High-Speed Gas Turbine Pump …
adjustments are needed, otherwise the deviation of combustion pressure will
certainly exceed the allowable deviation.
If n Æ Dn ¼ 0:28 1 Æ 4%
ð
Þ is used, the corresponding deviation of combustion pressure is Æ1:5%.
If a T Æ Da T ¼ 0:00282 1 Æ 3%
ð
Þ is used, the corresponding deviation of
combustion pressure is Æ1:3%.
After adjustment, the order of main parameter deviation and its influence on
combustion pressure deviation is as follows:
(a) The relative manufacturing accuracy of nozzle diameter and grain
diameter are still þ 1:3% and À0:13%, respectively, which still affects
the combustion pressure deviation d 1 ¼ À5:5%.
(b) The relative deviation Æ4% of the grain pressure index affects the
combustion pressure deviation d 2 ¼ Æ1:5%.
(c) The relative deviation Æ3% of the grain temperature sensitivity coefficient affects the combustion pressure deviation d 3 ¼ Æ1:3%.
The deviations of main parameters are eventually allocated and determined
by working nozzle design drawings and retarded grain development task
book.
(2) Computation of Combustion Pressure Comprehensive Deviation
Calculating criteria: It mainly depends on the combined effects of the
combustion pressure deviation d 1 caused by the relative manufacturing
accuracy of nozzle diameter and grain diameter, the combustion pressure
deviation d 2 caused by the relative deviation of grain pressure index, and the
combustion pressure deviation d 3 caused by the relative deviation of grain
temperature sensitivity coefficient.
Calculating method: In engineering practice, it should not only be considered
that the maximum of each deviation is unlikely to occur at the same time, and
that the three deviations are unlikely to overlap without compensation, but also
take into account the actual situation of small batch production and production
instability in the development process. Therefore, the three deviations should be
added up by statistics and multiplied by a certain coefficient as the comprehensive deviation of combustion pressure. The computational equation is
k ¼ 1:2
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
r 2
1 þ r 2
2 þ r 2
2
q
ð9:37Þ
where
k Combustion pressure comprehensive deviation;
d 1 Combustion pressure deviation caused by relative manufacturing accuracy of nozzle and grain diameter;
134
9 High-Temperature and High-Speed Gas Turbine Pump …