Analysis of Tangential Combustion Instability Modes in a LOX/Kerosene Liquid Rocket Engine Based on OpenFOAM

Self-excited high frequency combustion instability (HFCI) of first-order tangential (1T) mode was observed in a staged-combustion LOX/Kerosene liquid rocket engine numerically. Two different kinds of 1T patterns, standing wave mode and traveling wave mode, were captured in the present work. In the nominal operation condition, the ratio of oxygen-to-fuel (O/F) was 2.5. Propellant was evenly distributed in all injectors and no HFCI occurred. The chamber pressure obtained from the numerical simulation and experiment showed a good agreement, which validated the numerical model. When the mass flow of fuel for two injectors was modified, severe HFCI occurred. The pressure wave node was located at a fixed diameter, showing a 1T standing wave mode. As the O/F was set 4.4 and the propellant distribution was completely uniform, the numerical result yielded a 1T wave node featured a spinning behavior, which was a traveling 1T wave mode. Once the HFCI arose, no matter what standing mode or spinning mode, the pressure and heat release oscillated totally in phase temporally and coupled spatially. The heat release from combustion was fed into the resonant acoustic mode. This was the thermoacoustic coupling process that maintained the HFCI.

Development of fault diagnosis platform for liquid rocket engine based on experimental data

Aiming at the defects of difficult to establish fault diagnosis models caused by the small scale of liquid rocket engine test data, imbalanced categories and high fault coupling, the fault diagnosis platform with 10 fault diagnosis models are developed for fault diagnosis, covering K-nearest neighbor (KNN) model, optimized KNN model, logistic regression (LR) model, optimized LR model, support vector machine model, K-means model, decision tree model, neural network model, random forest model and light-GBM model. The prediction accuracies of these models are validated based on the experimental data. Among these models, the light-GBM model provide the best prediction accuracies, and 5 models have the prediction accuracy larger than 98%.

Physical model of noise in the combustion chamber of a liquid-propellant engine

В статье рассмотрена задача определения резонансных характеристик камер сгорания жидкостного ракетного двигателя. Приведён и математически обоснован подход к созданию алгоритмов решения такой задачи с помощью анализа спектральной плотности мощности шумовых сигналов параметров рабочих процессов. Рассмотрены вычислительные эксперименты и продемонстрированы их результаты для модельного сигнала с единственной модой. In this article a task of determining of resonance characteristics for combustion chambers of a liquid rocket engine. The approach for development of algorithms to solve this task using analysis of power spectral density of noise signals of working procedure parameters is considered and mathematically justified. Computational experiments are considered and their results for a model signal with a single mode is demonstrated.

Test Results of a Model Additively Manufactured Oxygen-Methane Combustion Chamber of a Liquid Rocket Engine

The paper focuses on an experimental unit developed for modeling combustion characteristics in a model oxygen-methane combustion chamber of a liquid rocket engine. The key components of the unit, i.e., the mixing head of the combustion chamber and the regeneratively cooled nozzle, were manufactured using advanced methods of additive manufacturing. The paper emphasizes the specific character of the combustion chamber components made with the use of additive technology and introduces hot-fire test results of the model combustion chamber as part of the experimental unit. The study shows the durability of the mixing head and combustion chamber nozzle under hot-fire test conditions, as well as the reliable operation of the experimental unit as a whole, which confirms the selected design and technological solutions. Within the study, we analyzed the cooling system of the experimental unit for the test conditions, estimated the thermal state of the nozzle, with account for the features of the additively manufactured cooling path. To increase the cooling system’s reliability and expand the combustion chamber pressure application, it is recommended to apply a heat-shielding coating on the firewall of the nozzle. Using new experimental data, we analyzed the parameters of improving the efficiency of the model combustion chamber with the additively manufactured components and corresponding in scale and consumption characteristics to the combustion chamber of the liquid rocket engine