scholarly journals MATHEMATICAL MODEL OF HOT-AIR BALLOON STEADY-STATE VERTICAL FLIGHT PERFORMANCE

Aviation ◽  
2021 ◽  
Vol 25 (3) ◽  
pp. 149-158
Author(s):  
Nihad E. Daidzic
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Flight Performance ◽  
Balloon Flight ◽  
Flight Tests ◽  
Flight Planning ◽  
Hot Air ◽  
Ideal Gases ◽  
External Flows ◽  
Steady State Performance

Vertical flight performance of Lighter-than-Air free hot-air balloons is derived and discussed. Novel mathematical model using lumped-parameters has been used to model balloon flight dynamics and steady-state performance in particular. Thermal model was not treated as the super-heat is under the control of aeronauts/pilots. Buoyancy or gross lift, net or effective lift, specific lift, and excess specific lift were derived for a general single envelope balloon and can be applied to hot-air, gas and hybrid balloons. Rate-of-climb, absolute ceiling, rate-of-descent, and the maximum rate-of-descent or the uncontrolled terminal descent have all been modeled and sample computations performed for AX8 or AX9 FAI-class hot-air balloons. Lifting index or the specific net/effective lift have been computed treating ambient and hot air as ideal gases at various pressure altitudes and representative envelope temperatures. Drag coefficient in upward and downward vertical flights have been chosen based on best available data. Experimental scale and full-scale flight tests are suggested for more accurate estimates of external aerodynamics in vertical balloon flights. CFD computations of coupled inner- and external-flows are also recommended in future efforts. Knowledge of free balloon’s vertical performance is essential in flight planning and operational safety of flight.

Validation of a rotorcraft mathematical model in autorotation by use of gyroplane flight tests

2004 ◽  
Vol 108 (1079) ◽  
pp. 51-58 ◽  
Author(s):  
V. M. Spathopoulos
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Research Work ◽  
Main Rotor ◽  
Rotor Speed ◽  
Flight Tests ◽  
Handling Qualities ◽  
Alternative Approach ◽  
Mode Of Operation ◽  
Engine Failure

Aircraft handling qualities in autorotation are critical in determining the level of safety of rotorcraft. For helicopters suffering from an engine failure, transcending from powered to autorotative flight occurs rapidly and requires immediate and accurate pilot reaction. Although it is important for the handling qualities in this flight state to be predicted correctly, obvious difficulties will exist in using flight tests as a means of validation when autorotation constitutes an abnormal mode of operation. In the research work presented in this paper an alternative approach is applied, of configuring a generic rotorcraft model as a gyroplane, a type of vehicle for which its main rotor is constantly in autorotation. Flight tests are used for the validation purposes both for steady state and dynamic response cases. Results are produced to complement those already existing for a dissimilar gyroplane type thus increasing the level of confidence obtained. It is concluded that important handling qualities indicators such as the steady state trends are correctly predicted although limitations are imposed due to rotor speed discrepancy.

Theoretical and Experimental Studies of the Steady State Performance of an Orbital Rotor Low-Speed High-Torque Hydraulic Motor

1996 ◽  
Vol 210 (6) ◽  
pp. 423-429 ◽  
Author(s):  
K Dasgupta ◽  
A Mukherjee ◽  
R Maiti
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Experimental Studies ◽  
Engineering Systems ◽  
Hydraulic Motor ◽  
Low Speed ◽  
High Torque ◽  
Complex Variation ◽  
Structured Approach ◽  
Steady State Performance

In this paper the steady state performance of epitrochoid generated orbital ‘rotary piston machine’ (ROPIMA) type ‘low-speed high-torque’ (LSHT) hydrostatic unit has been studied. The complex variation of the volume of a chamber of such a machine with shaft rotation, along with the various flow and torque losses, demand a structured approach to arrive at its mathematical model. In conventional approaches the system morphology becomes obscured as the mathematical model is approached. Bondgraph provides a structured approach to model engineering systems in a simplified manner. A reduced Bondgraph model of the LSHT Orbital motor is made where the various losses are lumped in suitable resistive elements. The variations of the loss coefficients are identified. The predicted performance of the motor has been experimentally verified.

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance

A Novel Control Scheme for PWM Boost Converter based on Sliding Mode Control using Particle Swarm Optimization

2020 ◽  
Vol 14 ◽  
Author(s):  
Gang Liu ◽  
Dong Qiu ◽  
Xiuru Wang ◽  
Ke Zhang ◽  
Huafeng Huang ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Steady State ◽  
Sliding Mode ◽  
Particle Swarm ◽  
Mathematic Model ◽  
Absolute Error ◽  
Boost Converter ◽  
Sliding Mode Controller ◽  
Swarm Optimization ◽  
Steady State Performance

Background: The PWM Boost converter is a strongly nonlinear discrete system, especially when the input voltage or load varies widely, therefore, tuning the control parameters of which is a challenge work. Objective: In order to overcome the issues, particle swarm optimization (PSO) is employed for tuning the parameters of a sliding mode controller of a boost converter. Methods: Based on the analysis of the Boost converter model and its non-linear characteristics, a mathematic model of a boost converter with a sliding mode controller is built firstly. Then, the parameters of the Boost controller are adjusted based on the integrated time and absolute error (ITAE), integral square error (ISE) and integrated absolute error (IAE) indexes by PSO. Results: Simulation verification was performed, and the results show that the controllers tuned by the three indexes all have excellent robust stability. Conclusion: The controllers tuned by ITAE and ISE indexes have excellent steady-state performance, but the overshoot is large during the startup. The controller tuned by IAE index has better startup performance and slightly worse steady-state performance.

scholarly journals Steady state performance of improvised ufer grounding practice

2014 ◽  
Author(s):  
Siow Chun Lim ◽  
Mohd Zainal Abidin Abd Kadir ◽  
Chandima Gomes ◽  
Norhafiz Azis
Keyword(s):  
Steady State ◽  
Steady State Performance
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