Page 195 - Kỷ yếu hội thảo quốc tế: Ứng dụng công nghệ mới trong công trình xanh - lần thứ 9 (ATiGB 2024)

186 TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT - ĐẠI HỌC ĐÀ NẴNG

coefficient of thermal expansion of C45 alloy steel is
0.28 [8].
According to the results of the durable pressure
simulation (Figure 2a), we can see that the
compressive strength of C45 alloy steel is 400 MPa,
8
2
equivalent to 4 × 10 N/m . The simulation results
show that the highest pressure-bearing area of the
nozzle pushbar is the cross-section in direct contact
with combustible gas. The maximum pressure that the
Figure 2. Test results of the valve seat nozzle details nozzle pushbar receives under operating conditions is
2
Testing durability for valve base (a); Pmax = 1,990.107 (N/m ). This limit is fully in line
with the compressive strength limit of the C45 alloy
Heat transfer test for valve base (b)
steel material, which ensures that the details of the
Thermal durability test results for the valve seat: nozzle pushbar are durable when operating.
According to the heat transfer test results (Figure Durable heat test method of the nozzle pushbar:
2b), the melting temperature of the C45 steel alloy is For the nozzle pushbar detail, the temperature
1500°C [9]. The simulation results showed that the
highest temperature-resistant area of the valve base simulation is equivalent to the bottom valve detail due
was the cut surface that was in direct contact with the to the same working conditions. The largest
temperature received by the propulsion at the end of
ignition gas. The maximum temperature this detail the compression stroke and the beginning of the
receives under operating conditions is 1427°C, which o
is lower than the melting temperature of the material. expansion stroke is Tmax = 1700 K = 1426.85 C [4].
It should be detailed to ensure heat resistance and no Since the nozzle pushbar receives the pressure as
melting during operation. And this temperature combustible gas pressure, the contact cross-section
appears in a short period of time at the end of the should also be considered. The cross-section of the
compression stroke and the beginning of the beginning nozzle pushbar surface in contact with combustible
of the expansion stroke, so the heat transfer time is gas pressure is calculated by:
very short. On the other hand, the heat generated will 2
exchange heat with the cooling system, so the heat S =πr (19)
resistance is absolutely guaranteed. However, all In it, r is the radius of the circular cross-section in
materials will expand when exposed to high direct contact with combustible gas; the heat transfer
temperatures, and when expanded several times, the coefficient of C45 alloy steel is 46.5.
mechanism of the material will decrease and affect Temperature simulation is carried out under the
the lifespan of the materials, so for long-term use, the condition of temperature exchange detail with the
cooling system needs to be arranged to optimize the environment at 27°C. Detailed heat resistance test
operation process. results of the nozzle pushbar:
The simulation results showed that the valve base
details have stable heat transfer and do not affect the
other parts of the nozzle.
3.3. Nozzle pushbar
The maximum pressure received by the nozzle
pushbar is the same as the pressure received by the
bottom of the valve at the end of the compression
stroke and the beginning of the combustion stroke:
Pmax = 23 bar [1]. Since the pushbar of the nozzle
receives pressure as pressure, the cross-section of the
applied face is an important parameter.
The area of the injector pushbar surface in contact
with the combustible gas pressure is calculated as Figure 3. Test results of the nozzle pushbar details
follows:
Testing durability for nozzle pushbar (a);
2
S = πr (18) Heat transfer test for nozzle pushbar (b)
In it, r is the radius of the circular cross-section in The melting point of C45 alloy steel is 1520°C.
direct contact with combustible gas; the Poisson The simulation results show that the highest

ISBN: 978-604-80-9779-0