328: Chapter 328's data is excellent! Change direction!

The convergence curve was very stable, with no signs of divergence. A few hours later, the results began to output one after another.

Zhao Yang flipped through the graphs and contour maps of various parameters one by one. The spectrum curve of the combustion chamber pressure pulsation was even better than he had expected!

The pulsation peaks of the four thrust chambers were evenly staggered in the frequency domain, and no superposition resonance occurred at any frequency point.

Furthermore, the transient response curve of the turbopump's axial force was extremely stable under all testing conditions. The uniformity deviation of the flow distributor under rated conditions was only 0.3 percentage points, a further decrease compared to the scale model tests.

When he saw the comparison curves for the combustion efficiency of the last few sets of thrust chambers, his pen tip paused.

The combustion efficiency curve almost flattened against the upper limit of the theoretical calculation. This is a rare occurrence in engineering; theoretical values are mathematical derivations under ideal conditions, while actual products always have various losses and deviations. Typically, achieving ninety-five percent of the theoretical value is considered an excellent design.

However, his configuration's combustion efficiency at several core operating points reached over ninety-eight percent of the theoretical value. The energy utilization efficiency was extremely high, and more importantly, it was stable enough—the efficiency fluctuations under all conditions were within one percentage point. For rocket engines, stability is sometimes more important than efficiency. If an engine experiences combustion instability in the sky, no amount of thrust will help.

A look of intense excitement appeared in Zhao Yang's eyes. With this modeling data, he could persuade Chief Engineer Sun to try changing the technical route.

He exported and printed a copy of the key data from the full-scale simulation. Holding the stack of papers that still carried the warmth of the printer, he walked out of the Supercomputing Center.

Chief Engineer Sun was in his office looking through a failure analysis report for a liquid hydrogen pump. When Zhao Yang entered, he was circling a number on a table on one of the report's pages with a red pen.

"Chief Engineer Sun, stop for a moment and take a look at this first."

As he spoke, Zhao Yang placed the modeling data on the desk with a smile. Chief Engineer Sun looked up at him, put down his pen, picked up the stack of papers, and began flipping through them from the beginning.

Zhao Yang didn't sit down; he just stood by the desk and waited. Chief Engineer Sun flipped through quickly but stopped when he reached the page with the combustion efficiency comparison curves.

He held the page close and looked at it for a while, then flipped back to compare it with the previous sets of data. He then placed the entire stack on the desk, took off his reading glasses, and pinched the bridge of his nose.

"You're giving me a difficult problem."

Chief Engineer Sun frowned and leaned back in his chair. His fingers tapped lightly on the edge of the desk twice, and a hint of helplessness flashed in his eyes.

"The route for the Long March 5A rocket engine was settled long ago. Currently, eighty percent of the workload has been completed, and several rounds of test runs have been conducted. Hundreds of people in the entire department have been working on it for so long; everyone's hard work is tied to that route. Now you suddenly want to change the technical route—"

"The data is right here."

Zhao Yang shrugged and said to Chief Engineer Sun with a smile.

"The four-thrust-chamber configuration is clearly superior to the dual-engine parallel scheme in terms of combustion efficiency and stability. I'm not talking about theory; I'm talking about simulation results. I've also brought the data from the scale model tests, and the two sets of data align."

Chief Engineer Sun didn't answer immediately. He picked up the stack of papers and flipped through them again. When he reached the transient response curve of the turbopump's axial force, his brow furrowed for a moment before slowly smoothing out. He put the papers back on the desk and sighed.

"This data is indeed good. Good enough to exceed my expectations."

He was silent for a few seconds, then looked at Zhao Yang and said helplessly,

"But changing the technical route isn't something I can decide on my own. The project timeline for the Long March 5 is very tight, and the higher-ups have been pushing. Changing the configuration at this point—the risk assessment isn't something I can finalize by myself."

"How about I go and ask the leadership?"

Zhao Yang said, looking at Chief Engineer Sun.

Chief Engineer Sun waved his hand, stood up from his chair, and put the stack of data into his briefcase.

"I'll go instead. I trust your technical judgment, but when it comes to project coordination and risk assessment, some things are better coming from me than from you directly."

He picked up the thermos on the desk, took a sip, and then looked at Zhao Yang.

"Go back to the research group and wait for now. I'll let you know if there's any news."

"Alright."

Chief Engineer Sun took Zhao Yang's modeling materials to find the leadership of the Space Agency. The Deputy Director was surnamed Liu, in charge of the project initiation and development of the carrier rocket series. He had worked at the Space Agency for over twenty years and had experienced the entire process from demonstration to the maiden flight of several models.

Chief Engineer Sun laid out Zhao Yang's full-scale simulation data and the scale model test report on Deputy Director Liu's desk and explained each item. After listening, Deputy Director Liu didn't immediately state his position but instead asked a question: What is the current progress of the original YF-77 dual-engine parallel scheme?

Chief Engineer Sun said that eighty percent of the workload had been completed and the test run data was basically qualified, with the remainder mainly being optimization and reliability verification. Deputy Director Liu nodded and said that there was still time.

"Gather the people from both sides and hold an evaluation meeting."

Deputy Director Liu moved Zhao Yang's modeling data closer to himself.

"The launch of the Long March 5 is imminent. Changing the configuration at this time is no small matter; the judgment of just one chief engineer isn't enough. Call in the other chief engineers and experts from the agency, and everyone will discuss it together."

The evaluation meeting was scheduled for three days later in the large conference room of the Space Agency's main building. The oval conference table was full of people. Besides Deputy Director Liu and Chief Engineer Sun, there were several major chief engineers and senior academicians from the Space Agency.

At the start of the meeting, Chief Engineer Sun first gave a brief report on the progress of the YF-77 dual-engine parallel scheme. He stated that the current test data for this scheme basically met the standards, and the remaining work was mainly reliability verification and optimization of individual operating conditions. According to the original schedule, it would not affect the overall progress of the Long March 5.

Then he gave a technical introduction to Zhao Yang's four-thrust-chamber configuration with a shared single turbopump, covering everything from the principle of pulsation phase cancellation to the scale model test data and the full-scale simulation results. After finishing, he distributed summaries of the two sets of data to the attendees for circulation.

The conference room fell silent for a moment as everyone carefully reviewed the data materials for a while. Everyone's expression was solemn. After thoroughly reviewing the materials, the discussion began.

The first to speak was Academician Luo, who sat to the left of Deputy Director Liu. He had completely white hair, thick eyebrows, and a deep voice.

"Dr. Zhao's configuration is indeed very imaginative in theory. Staggering the pulsation phases of the four thrust chambers to solve the coupling resonance problem at its root is an idea that has been proposed before, but he is the first to achieve such beautiful simulation data."

He paused and said with a somewhat hesitant expression,

"But my concern is that this is a completely new configuration. A new configuration means new processes, new experimental verifications, and a new accumulation of reliability data. The Long March 5 can no longer afford delays; we cannot overturn the entire project's timeline just because of a new scheme that looks good on paper."