From Golmud to Tianshui, the mission journey of "Huangying" engine

——Haery's 43-day original test was successfully completed
In a relatively altitude environment, the air is thin and the ambient temperature is low, and the amount of gas entering the cylinder becomes smaller. In order to achieve better combustion and starting conditions of the engine, data in a relatively altitude environment need to be obtained to correct different atmospheric pressure fuel injection parameters. From June 17 to July 29, 2019, Haery and his seven members rushed to Golmud City to carry out relatively original experiments.
This relatively original experiment was mainly carried out in several locations in Golmud City, Nachitai, Xidatan, Kunlun Pass and Tianshui City. At an altitude of 4700m and below, the test bench layout is shown in Figure 1. The single engine is equipped with four fans to simulate the incoming flow of airplanes, and the combustion in the cylinder is monitored in real time through a combustion analyzer, cylinder head temperature sensor, and exhaust temperature sensor. After calibration, the "Huangying" engine reached the starting calibration target at an altitude of 3500m; the external characteristic calibration, partial load calibration, low stable combustion conditions calibration and power testing tasks at each working point were completed at an altitude of 4000m and 4700m.

"Huangying" is a horizontally opposed 4-cylinder heavy oil aircraft engine. It adopts compression combustion technology, relatively pressure common rail, and electronic control system. It has the characteristics of low fuel consumption, long flight time, stable power output, and convenient maintenance.
"Huangying" was equipped with a drone to obtain data of 4700m-6300m above sea level. The two powered pods were respectively equipped with the left and right wings of the drone. The single powered pod was equipped with two engines, which can output different electrical powers according to changes in load demand. In this case where there is little test data acquisition, there are two aspects in order for the engine to operate stably at altitude:
1. Data preset: After obtaining the altitude experimental data of 3500m, 4000m and 4700m, the control parameters with altitude, temperature and speed are compared in detail, and the control parameters above 4700m are corrected;
2. Control strategy: Optimize the threshold of the restart control strategy and add strategies such as preheating plug control and smaller power generation control to improve the combustion of the engine at a higher altitude.
After repeated data analysis, debugging and software optimization, the "Huangying" engine was able to maintain stable combustion at an altitude of 6300m, and achieved phased results compared with the original test. In the past 40 days, Haery has accumulated valuable experience in hardware design, software function design and control strategy framework construction related to engine matching and motor set matching; at the same time, the "Huangying" engine has gradually improved the more original control logic during the test, which has served as a guiding role for the subsequent optimization of its own and other Haery models of the original test control logic.