Helicopter Engine Research Articles

A Comparative Study of Sustainable Energy Brayton Cycles in the Oil and Gas Industry. Part 1: Performance

Brayton cycles are open gas turbine cycles extensively used in civil aviation and the petrochemical industry because of their advantageous volume and weight characteristics. With the bulk of engine emissions associated, it is necessary to promote their environmentally-friendliness, including sound technical performance regularly. This research considers high bypass-low specific power plants in aviation and aero-derivative gas turbines combined-heat-and-power generation in the petrochemical industry. The investigation encompasses the comparative assessment of simple and advanced gas turbine cycle options including the component behaviour of the systems. This comprises the performance module. The research has contributed to understanding the technical performances of simple and advanced cycle helicopter engines, and aero-derivative industrial gas turbine cycles at design and off-design conditions. The simple cycles were modified for better fuel burn and thermal efficiency by using some additional components to form the advanced cycles. The helicopter engine investigated was converted to a small-scale aero-derivative industrial engine. Modeling the combined-heat-and-power performance of the small, medium, and large-scale aero-derivative industrial gas turbines was also implemented. The contribution also includes understanding the technical performances of both simple and advanced aero-derivative gas turbines combined heat-and-power at design and off-design A case study underlies the development and deployment of this model. The novelty is the conception of a tool for predicting the most preferred simple and advanced cycle aero-derivative engines combined heat-and-power generation in the petrochemical industry and the derivation of simple and advanced cycle small-scale aero-derivative industrial gas turbines from helicopter engines.

Fault Detection on Short-Haul or Highly Dynamic Flights Using Transient Flight Segments

Abstract A machine learning-based approach is presented, which allows to detect persistent engine faults after a single flight. It utilizes transient in-flight measurements and a transient engine model. The time series of the residuals between the measured data and the data resulting from performance synthesis is evaluated using moving windows containing at least one transient segment. A continuous wavelet transformation and a pretrained convolutional neural network are utilized on the residuals for feature extraction. The fault detection is carried out via a one-class support vector machine, trained exclusively on nominal engine operation data. Therefore, the approach requires no a-priory knowledge of the effects of engine faults on the in-flight measurements. Under the assumption of persistent faults, all windows of a single flight, which contain at least one transient segment, are considered in order to improve the reliability of the fault detection. This approach is validated using measured data of a small helicopter engine that replicates the dynamic flight of the corresponding model helicopter on a ground test bed. Consequently, step changes as well as complex variations of the shaft power output are considered. Four standard gas path sensors are considered. The one-class support vector machine is used successfully to detect two types of total pressure sensor anomalies. Assuming a typical number of transient segments for an average short haul flight, it turns out that persistent faults can be detected within one flight with a probability of above 90%.

Analysing temperature distributions in turbine first-stage rotor blades of a helicopter turboshaft engine

In helicopter turboshaft engines, turbine blades operate under extreme conditions. With increasing engine power, the gas temperature following the combustion chamber can reach approximately 1300 K. The turbine rotors endure significant centrifugal forces due to their high rotational speeds. Additionally, they experience thermal and aerodynamic loads from the flow of combustible gases, which non-uniformly impact the turbine blades at high temperatures. Furthermore, the mechanical properties of turbine blade materials are limited and strongly influenced by operating temperatures. This article presents a numerical investigation focusing on the temperature distribution of first-stage turbine rotor blades that do not feature internal cooling channels. The results indicate the regions of peak temperatures and evaluate rotor blade strength. Comparative analysis between theoretical and numerical calculations of blade temperature distribution reveals minor disparities: approximately 30 degrees at the blade shroud, 8 degrees at the mid-span section, and 15 degrees at the hub. These variations amount to less than 3% at the shroud, 1% at the mid-span section, and 1.5% at the hub.

Thermodynamic Optimization and Energy-Exergy Analyses of the Turboshaft Helicopter Engine

Energy demand is a critical contemporary concern, with significant implications for the future. While exploring renewable or sustainable energy sources offers potential solutions, optimizing energy consumption in existing power generation systems is also key. Aviation accounts for a substantial portion of energy demand, underscoring the importance of energy efficiency in this sector. Conventional energy analyses may be misleading; hence, employing exergy-based analyses provides a clearer understanding of energy consumption. Also, most of these analyses do not include the effect of the turbine blade’s cooling in calculations. In the present study, exergy analyses have been conducted on a helicopter turboshaft engine with turbine-blades cooling, focusing on design parameters such as ambient temperature, compressor pressure ratio, and turbine inlet temperature. Thermodynamic optimizations are conducted using a genetic algorithm. Results show that increasing pressure ratio and turbine inlet temperature boost performance, yet technical restrictions on compressor and turbine size, and metallurgical constraints on turbine blades’ material limit these gains. Sea level scenario prioritizes ambient temperature-drop for enhancing net-work and efficiency, while altitude-gain boosts turboshaft performance. Combustion chambers incur the highest exergy destruction of 74-80%, followed by 16-20% and 4-6% exergy destructions in the turbine and compressor, respectively. Lower air temperatures and higher flight altitudes demand larger fuel consumption for equivalent turbine inlet temperature, albeit enhancing cooling capacity and reducing required cooling air fraction for turbine blades.

Investigating renewable and sustainable biofuel and biofuel/diesel blends utilizations in a turboshaft engine used on helicopters

In this study, biofuel, various biofuel/diesel blends and jet fuel are used in the turboshaft engine (TSE) of a helicopter. The analyses of thermodynamics, sustainability, environmental and cost formation are applied to the system, and the impacts of biofuel (B100) & its blends with diesel (B10D90, B20D80, B50D50) are compared with JP-8 jet fuel (JF100) and each other. TSE's energy efficiency is computed to be 25.18 %, while the exergy efficiency depending on the fuel type (from maximum to minimum) are found as JF100 (JP-8) (23.462 %) > B10D90 (23.367 %) > B20D80 (23.365 %) > B50D50 (23.359 %) > B100 (23.351 %). The exergy efficiency of the biofuel and its blends are slightly lower than the conventional jet fuel. However, the difference is lower than 1 %. So, the biofuel and its blends can be effectively used in the TSE of the helicopter. Sustainable efficiency factor rates of TSE are also very close for jet fuel (1.307) and biofuel & its blends (1.305). So, exergetic sustainability of the studied fuels are close to each other and they can be used in the helicopter engine in a sustainable way. Biofuel and its blends utilization can also reduce the environmental cost, specific environmental cost, social impact cost, specific social impact cost of CO2 for TSE.

Investigation On A Novel Injector Concept For Spinning Combustion Technology In High-Pressure Conditions By Advanced Laser-Based Diagnostics

Safran Helicopter Engines has recently patented the spinning combustion technology in which the burnt gases from one injector travel tangentially along the combustor annulus towards the neighboring injectors. Compared to conventional designs, the new kerosene injection systems are dedicated to improve air/fuel mixture ignition but also to further reduce NOx and soot particle emissions. Experimental studies are performed on these fuel injectors in a high-pressure/high-temperature combustion facility designed by the CORIA research laboratory. This test bench is able to reproduce the same operating conditions encountered in a helicopter combustor over the entire range of nominal operating conditions and has large optical accesses for the implementation of laser-based diagnostics. In the current paper, we present results concerning flame structure and NO formation in the primary zone under pressure conditions of up to 14 bar, using simultaneous OH-PLIF, NO-PLIF and kerosene-PLIF laser diagnostics. These experimental studies were supplemented by high-speed PIV measurements. A good spatial correlation between the distribution of liquid and vapour kerosene and the location of the flame front was observed. Depending on the operating conditions in terms of fuel/air ratio, mass flow rates and pressure, different flame structures resulting from the modification of the interaction between fuel injection and aerodynamics are observed. Furthermore, it was found that the Zeldovich pathway mainly controls the formation of NO in the vicinity of the flame front. In addition, the effects of FAR and pressure also have a significant impact on NO production. All these results are now intended to serve as a comprehensive validation database for the development and testing of high-fidelity LES tools dedicated to the simulation of reactive flows in aero-engine combustion chambers.

Multispecies Flow Indirect-Noise Modeling Re-Examined with a Helicopter-Engine Application

Composition noise has recently received increasing attention for its potential to contribute significantly to the indirect noise mechanism. In this study, the importance and definition of composition noise are revisited by proposing a new proper decomposition between entropy and mixture compositional fluctuations. When assuming quasi-one-dimensional, multispecies, isentropic, and nonreactive flow in nozzles, the resulting system of equations shows a new and remarkable one-way coupling between composition waves and both acoustic and entropy waves. Relying on the Magnus-expansion methodology, an exact solution of that system is investigated. The proposed theory is validated by comparing the model predictions with direct numerical simulations of nozzle flows in which compositional fluctuations are pulsed. It is shown that composition transfer functions from the unsteady simulations are in agreement with the analytical model of this paper. Finally, a hybrid approach is investigated consisting of extracting waves from a large-eddy simulation of a real helicopter engine and propagating those through different nozzle geometries. Composition noise is found to be negligible compared to direct or indirect entropy noise since it is at least 20 dB lower than other noise mechanisms for all tested cases.

Influence of Engine Dynamic Characteristics on Helicopter Handling Quality in Hover and Low-Speed Forward Flight

This study assesses the influence of engine dynamic characteristics on helicopter handling quality during hover and low-speed forward flight. First, we construct the helicopter–engine coupling model (HECM) based on the power-matching relationship between the engine and the rotor. The impact of the engine is evaluated by comparing HECM with a helicopter model without the engine. To assess the engine’s influence quantitatively, we consider torque response, height response, and collective–yaw coupling characteristics in ADS-33E-PRF handling quality criteria. The results reveal that the engine power output lag can deteriorate the helicopter’s torque and height response handling quality rate (HQR). After the increase in helicopter mass, the torque HQR caused by engine influence improved, and the altitude HQR further deteriorated. The engine dynamic characteristics can also reverse the yaw rate, decreasing collective–yaw coupling HQR. As the helicopter’s flight speed increased, the engine’s impact on the yaw rate increased by 41.8%. This study can provide valuable insight into the effects of engine dynamic characteristics on helicopter handling quality and offer a reference for the design of helicopter–engine coupling control laws.

Numerical Modelling of the 3D Unsteady Flow of an Inlet Particle Separator for Turboshaft Engines

Helicopter and turboprop engines are susceptible to the ingestion of debris and other foreign objects, especially during take-off, landing, and hover. To avoid deleterious effects, filters such as Inlet Particle Separators (IPS) can be installed. However, the performance and limitations of these systems have to be investigated before the actual equipment can be installed in the aircraft powerplant. In this paper, we propose different numerical methods with increasing resolution in order to provide an aerodynamic characterization of the IPS, i.e., from a simple semi-empirical model to 3D large eddy simulation. We validate these numerical tools that could aid IPS design using experimental data in terms of global parameters such as separation efficiency and pressure losses. For each of those tools, we underline weaknesses and potential benefits in industry practices. Unsteady flow analysis reveals that detached eddy simulation is the trade-off choice that allows designers to most effectively plan experimental campaigns and mitigate risks.

Performance Simulation of Thermodynamic Design for a New Turboshaft Engine

For a search and rescue (SAR) helicopter, the requirements of long-range and twin-engine are becoming increasingly important. In this paper, the overall performance of a new turboshaft engine for SAR helicopters is simulated. Firstly, the main performance parameters of competitor engines are collected and compared, and the thermodynamic cycle parameters of the new engine are proposed subsequently. Then, an engine model is created in Turbomatch and the overall performance of this model at the design point is calculated. Finally, the off-design performances at different conditions of output power, ambient temperature, altitudes and flight Mach numbers (Ma) are investigated. A strategy of variable stator vane (VSV) for the anti-surge control of the axial compressor is also introduced. The results of the performance simulation indicate that this engine is quite competitive with lower specific fuel consumption (SFC) and higher specific power (SP) compared to the current SAR helicopter engines.

On the numerical assessment of engine exhaust plumes with a scaled cowling

The ability to predict the characteristics of engine exhaust is important to determining heat signatures on various components of the aircraft body. This is often obtained through numerical means such as RANS, which however relies closely on the choice of the turbulence model for accurate predictions. In this study, predictions of exhaust plumes from four turbulence models are compared against results from particle image velocimetry of a scaled helicopter engine exhaust. These models include the standard k − ϵ, realizable k − ϵ, shear-stress transport (SST) k − ω, and Durbin’s turbulence models. All four turbulence models managed to capture the general shape of the exhaust when analyzed through the velocity contours at two measurement windows. However, the comparisons of velocity contours fail to describe the shift of the predicted plume from the experiments, which is important for fuselage/tail impingement. To obtain further insights to the shifts, a visual correlation in the form of a confidence ellipse through principal component analysis (PCA) is introduced and plotted for the predicted plumes. All the models’ plume predictions showed quantifiable shifts in their mean-centers when compared to the measurements. In terms of matching the measurements’ statistical maximum variance of the plume distribution at the furthermost plane, it was found that the realizable k − ϵ performed the best among the models. On the other hand, the SST k − ω and Durbin’s model performed the best in predicting bivariate ( x and y coordinates) distribution of the plume at the furthermost plane.

Rotational Speed Optimization of Coaxial Compound Helicopter and Turboshaft Engine System

In order to enhance the overall performance and operational efficiency of the integrated coaxial compound helicopter and turboshaft engine system, a preliminary study on the optimal rotational speeds was implemented based on multidisciplinary integration. First, the flight mechanics model of coaxial compound helicopter and the aerothermodynamic model of turboshaft engine were developed. Then, the minimum fuel flow of the turboshaft engine was selected as the optimization objective, and an integrated optimization method of optimal rotational speeds based on the golden section method was proposed according to fixed ratio transmission (FRT) and continuously variable transmission (CVT). Finally, the effect of the optimal rotational speeds on the overall performance of the integrated system was investigated, and the variation laws of the optimal rotational speeds under different operating modes were revealed. The results indicated that the optimal rotational speeds can decrease engine fuel flow by a maximum of more than 10%, which is conducive to promoting operational economy and overall performance. Moreover, the flight conditions, helicopter weight, and engine degradation significantly affect the optimal main rotor speed.

Fuel-saving and emission accounting: An airliner case study for green engine selection

In this research, differences in the quantities of hazardous emissions induced by equipping the first composite constructed narrow body aircraft, which is commonly used in commercial aviation today, with the most common engine combinations are examined. Each engine combination that is the subject of this research is actively deployed by a number of airlines and serves the majority of passenger transportation demands. The objective is to clearly depict the variation in the quantities of emissions generated by the various engine types employed in this commonly used passenger aircraft. The instability in the amounts of emissions in various flight phases of the same aircraft, performed with various engine specifications on the same trajectory and route, is determined using EUROCONTROL's Integrated Aircraft Noise and Emissions Modelling Platform (IMPACT), which is founded on the Base of Aircraft Data, Federal Office of Civil Aviation (FOCA), and International Civil Aviation Organization's (ICAO) Helicopter and Aircraft Engine Emission Database. The research seeks to answer the following question: Considering that airlines serve many destinations throughout the year, how much fuel saving and, indirectly, emissions mitigation are achieved per sortie as a result of replacing the engines used by airlines in their existing fleets with the most environmentally friendly equivalents?

Ринок та перспективи газотурбінних двигунів для важких транспортних гелікоптерів

The subject of this study is the current state of the market and prospects for the development of heavy transport helicopters and their power plants. This article provides a classification of helicopters and a segment of medium-heavy and heavy helicopters with gas turbine engines. The field of application of such helicopters is briefly described. The purpose of this article is to evaluate the activities of Element JSC in the field of developing electronic control systems for gas turbine engines for heavy class helicopters. Such systems for Element JSC, in particular, are RDTs-2500 and RDTs-450M-117B units for TV3-117VMA-SBM-1B series turboshaft engines, created by Motor Sich JSC. Objective: To provide information on the main types of heavy helicopters manufactured and operated today, as well as a description of the gas turbine engines installed on these helicopters. The field of application of such helicopters is briefly described. The segment of heavy helicopters with gas turbine engines is the largest in terms of money on the world market of civil helicopters, and the forecast of deliveries of such helicopters for the next 5-7 years is given. Most helicopter models are not completely new developments, but have been improved over many years. Characteristic design features of heavy helicopters with gas turbine engines, features of the arrangement of units and equipment are given. The main structural and structural features of gas turbine engines of various manufacturers and the types of helicopters on which they are installed are given. Brief information on Russian and Ukrainian gas turbine engines - VK-2500 and TV3-117VMA-SBM-1B is provided separately. The results. Despite the active development of eVTOL technologies in the sector of small rotorcrafts, the development and improvement of gas turbine engines continues. Heavy helicopters of both traditional and non-traditional designs are being developed. Conclusions. Modernization of the design and "remotorization" of the Mi-8 helicopter is a good opportunity for "Motor-Sich Helicopters", but it needs its own developments. Many promising Ukrainian developments were canceled due to the war. Analysis of the technical characteristics of TVaD for heavy helicopters shows that domestic engines are almost in no way inferior to their European and American competitors. Promising TVaD of SE "Ivchenko-Progress" AI-130 with a capacity of 3,000 hp. can become an even more attractive proposition.

Modelling of fire-suppressant injection into engine nacelle for various flight regimes

In this study, the injection of Halon 1301, an effective fire-suppressing agent, into a helicopter engine nacelle is modelled to provide insights into dispersion behaviour alongside complex flow physics. The injection velocity as well as the mass flow rate were retrieved via a 1-D pipe model to simulate nitrogen-pressurized flow of Halon 1301 in a four-branch pipe system. The Discrete Phase Model in ANSYS Fluent was then used to model the injection of Halon 1301 into an engine nacelle. To simulate engine operation conditions in forward flight and hover regime, external boundary conditions were prescribed to the pressure inlets in the nacelle. When Halon 1301 is injected into the engine bay via the first pair of injection points, the droplets immediately reach their boiling point of 215 K. This resulted in an explosive-dispersion behaviour with a cone angle in the range of 80°–90°. As the agent evaporates, the engine cools and another pair of injection points located at the rear of the engine is subsequently activated, helping to cool the engine further. The two flight regimes considered, namely, hover and forward flight, showed contrast in flow dynamics which affected the cooling of the engine as well as the spray dynamics. In particular, the forward flight case showed more recirculation zones compared to the hover case. The volume concentrations of Halon 1301 were plotted for 11 probe points within the nacelle, and it was observed that two locations showed traces of low concentration levels.

Water-Cooled Fast-Response Wall-Static Pressure Probes for Harsh Combustor Environment Applications

The present paper discusses the design methodology for a water-cooled fast-response wall-static pressure probe intended for measurements in the combustion chamber of gas turbines, as well as the results from a series of tests performed with the prototype of the probe mounted in the primary zone of the combustion chamber of a turboshaft engine test rig. The first part of the present paper reviews the design methodology of a water-cooled fast-response wall static pressure probe intended for measurements of combustion noise and instabilities in gas turbine combustors, describing the optimization of measurement performance in terms of frequency bandwidth ([0 – 40kHz]) as well as the design of the cooling layout ensuring the sensor’s integrity within a harsh environment. The second part of the paper focuses on the analysis of the results obtained from trial tests performed using the probe prototype mounted in the primary zone of the combustion chamber of a helicopter engine test rig. The strengths and strong potential for further growth of the current probe design are highlighted, while its shortcomings and (short-term) solutions to these shortcomings are also discussed.

Development and Investigation of a Fire-Resistant Aluminum–Glass Fiber Reinforced Plastic for a Helicopter Engine Cowl

Development and Investigation of a Fire-Resistant Aluminum–Glass Fiber Reinforced Plastic for a Helicopter Engine Cowl

Classification and Unified Expression of General Aircraft Product Functions

With the continuous progress of The Times, the complexity and innovation of products in the design and manufacturing process are gradually increasing. Because of the interdependence and coupling between the composition or function of complex products, the product development cycle is greatly extended, and the problem of low reuse in the design process is also caused. This paper aims at the problems of product function coupling, iteration and reuse. By analyzing the design status of domestic complex products and adopting the combination of black box model, complex network model and GA genetic algorithm. The model of product function classification and unified expression is put forward. Finally, the helicopter engine power plant is taken as an example to demonstrate. It helps demonstrating the validity of the research and provides an effective reference for the design of general aircraft product functions.

Chemical characterization of combustion engine exhaust and assessment of helicopter deck operator occupational exposures on an offshore frigate class ship

Diesel engine exhaust (DE) consists of a complex mixture of gases and aerosols, originating from sources such as engines, turbines, and power generators. It is composed of a wide range of toxic compounds ranging from constituents that are irritating to those that are carcinogenic. The purposes of this work were to characterize DE originating from different engine types on a ship operating offshore and to quantify the potential exposure of workers on the ship’s helicopter deck to select DE compounds. Sampling was conducted on a Norwegian Nansen-class frigate that included helicopter operations. Frigate engines and generators were fueled by marine diesel oil, while the helicopter engine was fueled by high flash point kerosene-type aviation fuel. Exhaust samples were collected directly from the stack of the diesel engine and one of the diesel generator exhaust stacks, inside a gas turbine exhaust stack, and at the exhaust outlet of the helicopter. To characterize the different exhaust sources, non-targeted screening of volatile and semi-volatile organic compounds was performed for multiple chemical classes. Some of the compounds detected at the sources are known irritants, such as phthalic anhydride, 2,5-dyphenyl-p-benzoquinone, styrene, cinnoline, and phenyl maleic anhydride. The exhaust from the diesel engine and diesel generator was found to contain the highest amounts of particulate matter and gaseous compounds, while the gas turbine had the lowest emissions. Personal exposure samples were collected outdoors in the breathing zone of a helicopter deck operator over nine working shifts, simultaneously with stationary measurements on the helicopter deck. Elemental carbon, nitrogen dioxide, and several volatile organic compounds are known to be present in DE, such as formaldehyde, acrolein, and phenol were specifically targeted. Measured DE exposures of the crew on the helicopter deck were variable, but less than the current European occupational exposure limits for all compounds, except elemental carbon, in which concentration varied between 0.5 and 37 µg/m3 over nine work shifts. These findings are among the first published for this type of working environment.

Sand Discharge Simulation and Flow Path Optimization of a Particle Separator.

A numerical simulation method is used to optimize the removal of sand from a helicopter engine particle separator. First, the classic configuration of a particle separator based on the literature is simulated using two boundary conditions. The results show that the boundary conditions for the total pressure inlet and mass flow outlet are much more closely aligned with the experimental environment. By modifying the material at the front of the shroud, the separation efficiencies of coarse Arizona road dust (AC-Coarse) and MIL-E-5007C (C-Spec) can be improved to 93.3% and 97.6%, respectively. Configuration modifications of the particle separator with dual protection can increase the separation efficiencies of AC-Coarse and C-Spec to 91.7% and 97.7%.