scholarly journals Nozzle flows found by the hodograph method. II

1960 ◽  
Vol 1 (3) ◽  
pp. 357-367 ◽  
Author(s):  
T. M. Cherry
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Test Section ◽  
Wind Tunnels ◽  
Perfect Gas ◽  
Supersonic Wind Tunnel ◽  
Hodograph Method ◽  
Sonic Nozzle ◽  
Polytropic Equation ◽  
Nozzle Flows

This is a sequel to a recent paper [1] on the construction by the hodograph method of trans-sonic nozzle-flows of a perfect gas. At the end of that paper it was shown how we can obtain regular flows that are ultimately uniform (as required in the test section of a supersonic wind tunnel), and the object now is to give some quantitative examples of such flows. The gas is supposed to have the polytropic equation of state Pρ−γ = constant, and the calculations have been made for the case γ = 1.4, with the Mach number M = 2.25 at the test section. The results, which are exhibited graphically, are indicative of what may be expected for other supersonic values of M, and it is hoped that they may be significant for the design of wind tunnels.

Design of a continuous portable indraft supersonic wind tunnel

2020 ◽  
pp. 030641902090734
Author(s):  
Monty Bruckman II ◽  
Lance W Traub
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Sound Level ◽  
Wind Tunnels ◽  
Supersonic Wind Tunnel ◽  
Blow Down ◽  
Hands On ◽  
Compressible Fluid Flow ◽  
Aeronautical Engineering ◽  
Design And Manufacture

Programs in mechanical and aeronautical engineering commonly include courses in compressible fluid flow. As such, learning can be greatly enhanced if theory is taught in conjunction with hands on experimentation. While supersonic wind tunnels are not uncommon at many universities, such facilities are generally of the blow down configuration. Consequently, run time is very short and ear protection is required during operation, potentially hindering instruction. Furthermore, blow down configurations are typically expensive and large. This article presents the design and manufacture of a continuous, indraft, miniature supersonic wind tunnel. The tunnel was designed for a nominal test section Mach number of 2; validation indicated a Mach number of 1.96 was achieved. Vacuum was provided by a regenerative blower. The facility is portable and quiet; measurements indicated that the sound level around the tunnel when operational was less than 81 dB (compared to 119dB generated by the department’s blow down supersonic wind tunnel).

Investigation of Transient Shock Wave in Supersonic Wind Tunnel

2012 ◽  
Vol 232 ◽  
pp. 228-233
Author(s):  
Behnam Ghadimi ◽  
Mojtaba Dehghan Manshadi ◽  
Mehrdad Bazazzadeh
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Wind Tunnel ◽  
Pressure Ratio ◽  
Wind Tunnels ◽  
Supersonic Wind Tunnel ◽  
Blow Down ◽  
Fortran Code ◽  
Nozzle Contour ◽  
Fluent Software

Wind tunnels are the experimental apparatuses which provide an airstream flowing under controlled conditions so that interesting items in aerospace engineering such as pressure and velocity can be tested. In this work, Shock wave passes through the intermittent blow-down wind tunnel at Mach=2,3,4 has been investigated. The shape of the nozzle contour for a given Mach number was determined using the method of characteristics. For this purpose MATLAB code was developed and this code was verified with Osher’s and AUSM methods, FORTRAN code and FLUENT software was used for these two methods, respectively. Dimensions of different parts of wind tunnel are determined and minimum pressure ratio for the starting condition has been founded using FLUENT software. Good agreement was considered compared with the data from eleven tunnels over their range of Mach number.

Analytical and Numerical Design of a High Performance Double–Throated Supersonic Blowdown Windtunnel

2016 ◽  
Author(s):  
Philipp Epple ◽  
Michael Steppert ◽  
Michael Steber
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Design Process ◽  
Test Section ◽  
Method Of Characteristics ◽  
Design Procedure ◽  
Optimum Shape ◽  
Supersonic Wind Tunnel ◽  
Convergent Nozzle ◽  
The Method Of Characteristics

In this publication the focus lies on the design process of the full supersonic double throated wind tunnel. Starting with the fundamental equations of gas dynamics in combination with an analytical model of the pressure reservoir, the area of the throat at the nozzle and the runtime of the blowdown wind tunnel were computed. Based on these results, the shape of a shock free nozzle was calculated by the method of characteristics. For this purpose, a nozzle design program was developed using Python. In order to validate the results of the method of characteristics program, these results were compared with the area-Mach number relation, which is the exact analytical solution of the isentropic flow through supersonic nozzles. The convergent part of the nozzle, which initially accelerates the flow to sonic speed, cannot be calculated by the method of characteristics, since it applies to supersonic flows only. Hence the subsonic convergent section of the nozzle was designed directly with 2D CFD using CD Adapco Star-CCM+ v. 10.06. A parametric model of the convergent nozzle section was used to find the optimum nozzle shape, i.e. a nozzle which results in a maximum mass flow rate in order to have an undisturbed flow field and Mach number in the following test section. In order to decelerate the flow again from supersonic to subsonic flow after the test section and minimize the total pressure losses, an oblique shock diffuser was used [1]. As for the convergent subsonic nozzle, the optimum shape of a diffusor was found by 2D CFD analysis. Putting all these elements together, i.e. nozzle, test section and diffuser the optimum supersonic wind tunnel shape was found. Finally, a full 3D simulation of the supersonic wind tunnel was performed in order to validate the complete design procedure and computations and also to include the viscous effect of the side walls. These results and the whole design process are presented and analyzed in the paper.

scholarly journals Some nozzle flows found by the hodograph method

1959 ◽  
Vol 1 (1) ◽  
pp. 80-94 ◽  
Author(s):  
T. M. Cherry
Keyword(s):  
Exact Solutions ◽  
Two Dimensions ◽  
Nozzle Design ◽  
Perfect Gas ◽  
Field Equations ◽  
Rigid Boundary ◽  
Hodograph Method ◽  
Isentropic Flow ◽  
Fixed Boundaries ◽  
Nozzle Flows

For investigating the steady irrotational isentropic flow of a perfect gas in two dimensions, the hodograph method is to determine in the first instance the position coordinates x, y and the stream function ψ as functions of velocity compoments, conveniently taken as q (the speed) and θ (direction angle). Inversion then gives ψ, q, θ as functions of x, y. The method has the great advantage that its field equations are linear, so that it is practicable to obtain exact solutions, and from any two solutions an infinity of others are obtainable by superposition. For problems of flow past fixed boundaries the linearity of the field equations is usually offset by non-linearity in the boundary conditions, but this objection does not arise in problems of transsonic nozzle design, where the rigid boundary is the end-point of the investigation.

The Effect of Pulsed Injection on Supersonic Shear Layer Mixing in a Scramjet Combustor

2018 ◽  
Vol 35 (3) ◽  
pp. 203-215
Author(s):  
Leslie Smith ◽  
Saeed Farokhi
Keyword(s):  
Wind Tunnel ◽  
Shear Layer ◽  
Test Section ◽  
Pulse Width ◽  
Static Pressure ◽  
Experimental Studies ◽  
Lower Wall ◽  
Supersonic Wind Tunnel ◽  
Scramjet Combustor ◽  
Secondary Injection

Abstract A novel injector has been designed and cold flow injection tests were performed in a modified supersonic wind tunnel. To complement these experimental studies three dimensional STAR-CCM+CFD simulations were developed. The pulse width may be varied, with options of injecting gas for 33 %, 50 % and 66 % of the injection period. The scramjet combustor environment is simulated in a supersonic wind tunnel through a backward facing step for secondary injection purposes and a 157.5 cm (62-inch) long test section. The gas in secondary injection is carbon dioxide and the primary flow is air. The simulations show a coupled interaction between the forcing from injection and the shear layer. Steady state static pressure measurements on the lower wall of the wind tunnel test section agree well with the simulated static pressure along the lower wall. The pulse width strongly impacts shear layer reattachment on the lower wall and varies between 2.4 and 4.3 step heights. Reduction in duty cycle from 66 % to 33 % at 1 kHz caused ~30 % reduction in the shear layer reattachments distance, which points to large scale mixing enhancement.

Design, Fabrication, and Realization of a Supersonic Wind Tunnel for Educational Purposes

2009 ◽  
Vol 37 (4) ◽  
pp. 286-303 ◽  
Author(s):  
Mohammed K. Ibrahim ◽  
A. F. Abohelwa ◽  
Galal B. Salem
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Compressible Flows ◽  
Basic Education ◽  
Design Parameters ◽  
High Tech ◽  
Design Phase ◽  
Supersonic Wind Tunnel ◽  
Design Error ◽  
Standard Textbook

The supersonic wind tunnel is an indispensable facility for basic education in any course that covers compressible flows and one of the main pillars of any aerodynamic laboratory. The introduction of a supersonic wind tunnel at the aerodynamics laboratory of the Aerospace Engineering Department at Cairo University had often been postponed and was hindered by a lack of funds for the purchase of foreign equipment and expertise. Thoughts therefore turned to building such facility instead of buying it, substituting high-tech and complex foreign equipment for locally produced equipment, and ‘thinking out of the box’ to make the most use of available resources, even when this led to some unconventional applications. An extensive scheme for the design, fabrication, and realization of a multi-Mach number ( M = 1.5, 2, and 2.5) supersonic wind tunnel for laboratory experiments is proposed in this paper. The proposed scheme is simple, detailed and multi-level; it starts by utilizing one-dimensional isentropic flow theory for the conceptual design phase and makes full use of computational fluid dynamics at the detailed design phase. This ensured that we had a working design before we embarked on the manufacture of any components, which would have been costly to modify had there been any design error. A parametric study has been carried out for a number of design parameters, using numerical simulations. After the design and fabrication, a number of successful standard textbook experiments, for Mach number 2, were carried out as validation for the proposed scheme. The results showed good agreement with the theoretical predictions.

Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter

2013 ◽  
Author(s):  
Jiaqi Xi ◽  
Qiang Zhang ◽  
Mian Li ◽  
Zhaoguang Wang
Keyword(s):  
Kalman Filter ◽  
Wind Tunnel ◽  
Flow Control ◽  
Extended Kalman Filter ◽  
Control Strategy ◽  
Test Section ◽  
Stagnation Pressure ◽  
Operating Conditions ◽  
Wind Tunnels ◽  
Wide Range

Supersonic wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiment, the stagnation pressure in the test section is required to remain constant. Due to the nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required, which is then capable of properly working under different operating conditions. In this paper, an Extended Kalman Filter (EKF) based flow control strategy is proposed and implemented in the controller. The control strategy is designed based on the state estimation of a real blowdown wind tunnel, which is carried out under an EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the controller parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

Numerical and experimental investigations on the reduction of wind tunnel wall interference by means of adaptive slots

2001 ◽  
Vol 105 (1052) ◽  
pp. 571-580 ◽  
Author(s):  
O. Meyer ◽  
W. Nitsche ◽  
I. Futterer
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Wind Tunnels ◽  
Experimental Investigations ◽  
Reference Case ◽  
Tunnel Wall ◽  
Promising Alternative ◽  
Model Flow ◽  
Flexible Walls ◽  
Basic Studies

Abstract The flow in many wind tunnel experiments is affected by the presence of test section walls. The resulting interference can be minimised by correcting the measured model pressures, or by influencing the model flow directly with the use of ventilated or adaptive test section walls. The objective behind the latter technique is to guide the flow in the test section to achieve low interference (i.e. free flow) condition at the model. The most successful technique of flexible, adaptive walls is still restricted to small research wind tunnels due to its mechanical complexity. However, a very promising alternative is the use of adaptive slots in the test section walls. This concept combines the method of passive slotted walls, as they are already implemented in many large wind tunnels, and flexible walls. Additionally, this technique presents the opportunity of full 3D adaptations because the slots can be situated in all four test section walls. This paper presents preliminary experimental results and the latest numerical calculations on the effectiveness of adaptive slots. The experiments were conducted under high subsonic flow conditions in the new slotted test section of the transonic wind tunnel at TU Berlin’s Aeronautical Institute (ILR). The numerical results presented are focussed on the 2D slot adaptation of a 2D-model (CAST7 aerofoil) and the 3D slot adaptation of a body of revolution (3D-ETB). In addition, basic studies were made of the flows associated with a single slot on one wall and a bump on the other. The numerical and the first experimental investigations have shown the potential of adaptive slots to reduce wall interferences effectively. The adaptation accuracy of the investigated slot configurations deviated not more than 3% from the reference case (2D-wall adaptation).

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