the following equation, as inlet condition, are given to the GT Power software.

(10)

3. Experimental

A heavy-duty diesel engine (16RK215) was tested in this study in the DESA Company in Iran. A model of this engine is shown in Figure 5. This is a turbocharged intercooled engine and the major parameters of the engine are shown in Table 2. Also environmental condition of the test is shown in Table 3. At the beginning the engine will start and leave it on for 2 hours to let the oil reach its normal temperature. This test was performed in four different stages.

At the first step, four rows of filters holes are blocked which equal to 17.4% of all holes and then the engine will work at 1000 rpm speed and at its full load. Next some parameters such as pressure cylinder and bearings, temperature inlet and out of the intercooler and other parameters are measured by processor. Also suction pressure is gauged by a computer.

The four steps of the procedure is repeated for air filter masking of 34.7%, 52.2% and 74%, each taking about 30 minutes. Hole masking of 17.4% and 74%, as two examples of the test are shown in Figure 6.

Some parameters gained from the test are listed in Table 4. Equivalent altitude is then calculated using pressure suction and considering the following equations:

(11)

(12)

4. Results and Discussion

1) Pressure drop prediction under different mass flow inlet and holes masking by the CFD

Pressure drop was measured at four mass flow rates and five percentage of masking by the CFD and the results are shown in Figure 7. Mass flow rate ranges from 1 kg/s to 4 kg/s. At mass flow rate of 1 kg/s the pressure drop rises from 0.376 KPa at 0% masking to 0.939 Kpa at 74% masking. At mass flow rate of 2 kg/s the pressure drop varies from 1.486 KP to 3.622 Kpa at 0% and 74% respectively.

Also it can be seen that the same value soars from 3.316 KPa to 8.108 Kpa and 5.789 KPa to 13.909 Kpa at mass flow rate of 3 kg/s and 4 kg/s for 0% and 74% masking respectively.

As can be seen, the pressure drop increases as mass flow rate rises. It can also be observed that for masking of 50% and higher, pressure drops increase more dramatically than the same value for masking of less than 50% which is not considerable.

2) Prediction of altitude at 16 RK215 engine in different speed engines As mentioned, pressure drop obtained as two parameters a and c according to equation 10 were input to the GT Power software. Table 5 shows the parameters obtained by the numerical method at 1000 rpm engine speed. In this table suction pressure and equivalent altitude are obtained by following equations;

(13)

(14)

As can be seen in Table 5, air filter holes masking does not have a significant effect on power and torque. It can also be observed that for masking of 50% and higher, altitude increases more dramatically than the same value for masking of less than 50%, which is not considerable.

According to Table 5 and interpolation equivalent altitude at different hole masking percentages can be gained. Figure 8 shows the altering of the altitude

Figure 4. Air filter at 16RK215 engine model using GT-Power.

Figure 5. A model of 16RK215 heavy-duty engine.

Table 1. Specification of the engine.

Table 2. Parameters of test engine.

Table 3. Environmental condition of the test.

against different masking of air filter holes.

To check the validity, Table 6 shows the comparison of numerical and experimental results in 1000 rpm engine speed. The computed altitudes are in good agreement with the measured data.

Figure 9 shows equivalent altitude at diverse speed engine.

In order to reach a certain equivalent altitude at reduced speeds, higher masking is required. For instance, to reach altitude of 400 m at 1000 rpm, 57.5% masking is needed while the value rises to 59.8% for 900 rpm and goes up to 61.9% at 840 rpm. When the engine is working at 690 rpm, masking proportion soars to 70.6% and finally to reach the same altitude at 570 rpm, 81% masking is required. Therefore at higher speeds, with masking, higher altitudes can be gained.

The following equations can be utilized to calculate

(a)(b)

Figure 6. Two model of masking during the test. (a) 74% of air filter hole’s masking; (b) 17.4% of air filter hole’s.

Table 4. The parameters that are obtained during test.

the number of rows and filters holes to be masked to reach a certain altitude.

(15)

(16)

The number of rows and holes of four engine speeds (rpm) are depicted in Figure 10.

5. Conclusions

In this paper, the impact of the masking on the altitude at heavy diesel engine (RK215) has been considered. The

Figure 7. Altering pressure drop with variety of mass flow in different masking holes at air filter.

Figure 8. Altering altitude with percentage of masking at 1000 rpm speed engine per the experimental and numerical methods.

Table 5. The parameters that are measured by the GT power at the 16RK215 engine.

main goal has been to investigate the altitude against different masking of the air filter holes. The investigations indicate that the numerical results have a good agreement with experimental data. Based on the results obtained throughout this study, the following conclusions are summarized;

Figure 9. Altering altitude with percentage of masking at four speed engine.

(a)(b)(c)(d)

Figure 10. Altering masking rows and holes with altitude in different speed engine. (a) N = 570 rpm; (b) N = 690 rpm; (c) N = 840 rpm; (d) N = 1000 rpm.

Table 6. Altering altitude with percentage of masking at 1000 rpm speed engine per the experimental and numerical methods.

1) The CFD code with the realizable k-ԑ turbulence model, predicts the pressure drop in air filter with a variety of air filter masking holes. It can clearly be seen that pressure drops depend on mass flow rate and percentage of masking.

2) With masking of the air filter holes can predict the altitude at different engine speeds, namely, in order to reach higher altitude, the number of masked holes rises. Also at higher speeds, with masking, higher altitudes can be obtained.

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NOTES

*Corresponding author.

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